I am in the process of finishing a portion of the basement for my wife to use as a sewing room. Drywall, carpeting, etc. No history of water problems but much plumbing nearby.
Should I use an arc fault breaker for the receptacles or a ground fault breaker which seems to be the usual recommendation for basement installations?
Thanks in advance.
Replies
Neither is required.
AFCI are required in bedrooms.
GFCI are required in UNFINISHED basements.
GFCI are required in UNFINISHED basements.
Most AFCIs also meet the GFCI requirements, so an AFCI can be used instead of a GFCI
woodturner9 said:
"Most AFCIs also meet the GFCI requirements, so an AFCI can be used instead of a GFCI"
Wrong!
While there are AFCI/GFCI breakers, they are not common.
Most AFCI circuit breakers do not offer GFCI protection; they contain a GFPE feature, that's "ground fault for protection of equipment". And it means that the AFCI breaker will open the circuit if there's 40 mA or more of ground fault current.
A GFCI breaker or device must open the circuit if there's 5 mA (+/- 1 mA) of ground fault current.
The purpose of a GFCI is to provide protection against shock and electrocution, and it's been determined that a healthy adult won't likely be electrocuted by 5 mA of current. The GFPE is intended to protect the equipment, NOT personnel.
Cliff
Have you seen the proposed changes for the 08 NEC?
It looks like the dual AFCI/GFCI breakers are going to be reguired on all circuits in newly constructed houses
What are you hearing?
Dave
If I could jump in, I thought I read they are going to be in the new code....'08..whether the AHJs decide to ignore that section remains to be seen.
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., wer ist jetzt der Idiot ?
Dave,
The draft 2008 NEC is available at this link:
http://www.nfpa.org/assets/files/PDF/necdigest/NEC2008ROPDraft.pdf
This "Report on Proposals" or ROP draft hasn't been voted on yet, so things could change in the next month or two.
The new AFCI language, in Section 210.12(b), requires combination AFCI protection of all single phase, 120v, 15A & 20A branch circuits in dwellings. Combination AFCIs are intended to offer protection against arcing in both the building wiring AND the connecting cords (and, I suppose, in the appliances too). The trip point for combination devices is 5 amps of arc current; compare that to the existing AFCI criterion of more than 75 amp arc current to trip.
My sense is that this language will be accepted as proposed. The idea of AFCIs for all branch circuits is like a runaway train. The proposrers of the requirement (AFCI manufacturers) tout AFCIs as providing a significant improvement in fire safety, but have to my knowledge provided no supporting documentation or predictions as to the cost/benefit ratio of the new requirement. Others have made calculations that show the cost/benefit to be astronomically high.
I suppose if the fire that an AFCI prevents is the one that might have killed one of my family, it'd be worth the societal cost. But then again, buildings would be more fire safe if they were all class one construction.
And, thanks for the kind words.
Cliff
Are there any combination AFCI's available yet?.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Bill,
Yep.
http://www.squared.com/us/products/circuit_breakers.nsf/unid/617D2D6F3F84CFB6852571F1005D526F/$file/comboafciFrameset.htm
Keep the faith, bro.
Cliff
My sense is that this language will be accepted as proposed. The idea of AFCIs for all branch circuits is like a runaway train. The proposrers of the requirement (AFCI manufacturers) tout AFCIs as providing a significant improvement in fire safety, but have to my knowledge provided no supporting documentation or predictions as to the cost/benefit ratio of the new requirement. Others have made calculations that show the cost/benefit to be astronomically high.
Thanks for the link. The general thought at the last meeting/class I attended was that it will add between $1000 and $1200 cost tonew builds, and panel upgrades. I don't do any residential work to speak of, so I just listen at the fringes of the group. The contractors and trade associations here have had some success with improving our licensing policy, but not much on specific code language adopted by the state.
Dave
Dave
CAP, I 've pretty much decided that this proposal is a done deal....I have been trying to stay current with this train wreck and have become resigned to the fact that since all this talk about these miracle devices some 11 years ago the Code has become the proving ground for manufacturers, while everyone in the chain including trade journals, contractors and distributors are all lining up to reap the profits from this 800# gorilla....there are folks everywhere that jumped on the bandwagon when these things came on the market mistakenly thinking they were adding more protection for themselves against pinched cords and failing equipment..I am now convinced that most of us were duped by the fact that these things were for protecting only bedroom circuits, because it sounded very "important" that only bedroom circuits should be on these breakers..
..the fact that bedrooms were probably the ONLY room in a house not protected by FA , Smokes or GFIs....or force fields and plasma puddles. is relevant now just for that reason: because the mfrs. have had a couple code cycles of folks throwing down their money and providing SqD ,Eaton, and others, free research The notable exception was of course the recall by SqD a few years backthere are folks here that thought wrongfully, that the current AFCIs would be protecting us from our own stupidity or laziness !
ignorant of their designed purpose.The truth is that by the time house wiring has deteriorated to the point of actually tripping one of these things
( around twenty years) it most likely won't work... or may have already been pulled out of the panel, but I looked into my crystal ball and see that twenty years from now folks won't even care about it . I still talk to folks that have no idea what a GFI isso, we will end up spending billions to put these things in and some folks will swear by them, and others at them.the power of advertising has come round to bite us.....twice.
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., wer ist jetzt der Idiot ?
Edited 3/11/2007 6:57 pm by maddog3
I am in the process of finishing a portion of the basement for my wife to use as a sewing room. Drywall, carpeting, etc. No history of water problems but much plumbing nearby.
Should I use an arc fault breaker for the receptacles or a ground fault breaker which seems to be the usual recommendation for basement installations?
Do you want to do it "to code" - to the minimum acceptable standards - or do you want to do it "right"?
Code only requires AFCIs in bedrooms - so an AFCI is not required. However, it's a good idea.
GFCIs meet the code requirement for interior below grade applications, so that is OK too. However, neither a conventional breaker or a GFCI protects well against arc faults - the most common cause of electrical fires.
Keep in mind, too, that with both AFCIs and GFCIs, they protect the downstream receptacles as well - you don't have to have one for each receptacle.
There is a lot of question whether AFCI's are "better" than code. That is why a number of locals don't even require AFCI's in bedrooms.Now GFCI's only add safety when there is some grounded surface where a person might possible get between the hot and the grounded surface.In a finished sewing room there would not be any such surfaces so it does not add any safety.
There is a lot of question whether AFCI's are "better" than code. That is why a number of locals don't even require AFCI's in bedrooms.
Not really - AFCIs trip, conventional breakers often don't. Simple as that. No real question at all that I've ever heard anyone voice. All the makers have pretty good demos to prove the point.
Haven't heard of any way an AFCI is not better than a conventional breaker, other than cost. What have you heard?
NEC requires AFCI's in bedrooms. If a local code differs from that, they would not be NEC compliant.
Now GFCI's only add safety when there is some grounded surface where a person might possible get between the hot and the grounded surface.
In a finished sewing room there would not be any such surfaces so it does not add any safety.
The room is below grade - so it's potentially damp, if not wet. The floor or wall may well be conductive enough to be the ground - it doesn't have to be soaking wet.
Edited 11/27/2006 12:15 pm ET by woodturner9
AFCI looks for rapid changes in load, which are typical of arcing. IIRC, they look at about 400 Hz. Many sewing machines get their variable speed using universal motors, so you might get a lot of nuisance tripping with AFCI.
I'd make the first receptacle a GFCI. It'll protect the ones downstream from it, and having it right there in the same room makes re-setting after a nuisance trip easier.
-- J.S.
There seems to be some confusion over what an AFCI is and how they work, so I am providing the following links:
http://www.eatonelectrical.com/unsecure/cms1/RE00402005E.PDF?GXHC_GX_jst=c7014444662d6164&GXHC_JSESSIONID=ced5761ad88149ef&
http://www.eatonelectrical.com/unsecure/cms1/RE00402003E.PDF?GXHC_GX_jst=c7014444662d6165&GXHC_JSESSIONID=e0291140922950b6&
Edited 11/27/2006 4:51 pm ET by woodturner9
That is the funnist thing that I have read in a long time.Have you read any of that stuff.From the first link."1- The main cause of electrical fires is resistance heating, an area not addressed by the AFCI""7- The requirement for the AFCI was adopted with minimal supporting data on a non-UL listed product. The consumer is now being used as a mandated test subject.
8- The original and present concern of the CPSC was the high percentage of fires being reported in homes 40 years old, not new homes.""The available fire data is not adequate to give an adequate confidence level to determine how many fires could be prevented by a properly functioning AFCI.""1- The original UL report to CPSC outlined 14 tests that were needed if ALL electrical fires were to be prevented. The present UL standard only contains 4 of those 14 tests. ""2- The most common cause of electrical fires is the overheated connection such as a loose wire nut, back wired receptacle, or corroded terminal screw. This type of heating is often referred to as resistance heating or “Joule heating”.
In an article by David Dini of Underwriters Laboratories Inc. in IAEI News - September/October 2001, he states For example, It should not be expected that those ignition scenarios representing Joule (I2R) heating would necessarily be prevented by an AFCI.An article by Dr. George Gregory of Square D Co. “Using Arc-Fault Circuit Interrupters to Reduce Residential Fires” states “An AFCI will not detect a glowing connection or hot spot, unless arcing is present.”An article in Fire Technology (vol 36, No.3) - co-authored by William King of CPSC states “Existing AFCI’s do not detect another cause of electrical fires - the glowing connection - unless an arc or ground fault is also present.”""3- Some allegations are being made that when resistance heating occurs, an arc will eventually result and the AFCI will operate. This is a true statement. As the fire spreads, it is extremely likely that the spreading fire will contact energized electrical wires and cause a fault. This may or may not occur before the fire spreads beyond the junction box. UL has proposed two tests, the Overheating Conductor: Hot plug; and the Overheating Conductor: Glowing connection (“Technology for Detecting and Monitoring Conditions that could Cause Electrical Wiring System Fires”, September 1995 pages 103 and 108). If indeed the AFCI will prevent resistance heating faults, they should be capable of passing these tests."THIS LAST ONE IS IMPORTANT. It is also what is mentioned in the 2nd Eaton paper. In many cases the AFCI will trip AFTER the fire is started. NOT BEFORE.
Aha! So now we know what the letters stand for: After Fire Circuit Interruptor. I'll file that one away along with Experimental Inadequate Fake Stucco. ;-)
-- J.S.
Have you read any of that stuff.
Yes, but apparently too quickly on the first link. From his intro, I thought he was explaining why those concerns weren't valid. A more careful reading reveals that is not the case, that he is arguing against making them mandatory.
Eaton had a good demo/paper online a while back, showing why AFCIs do work in those circumstances, but I couldn't find it when I looked earlier. I'll see if I can dig it up.
I still haven't been able to find the article I saw previously.
A couple of points about AFCIs, though:
1. They will trip at least as fast (generally faster) than a conventional breaker for a fault that will trip a conventional breaker
2. They will protect against ground faults at least as well as a GFCI.
3. They will trip on moderate overcurrents and arcing, which conventional breakers will not. (Conventional breakers require sustained overcurrent or massive overcurrent to trip. So, if you have a 15A breaker and a weak short that is drawing 20A, a conventional breaker MAY eventually trip, if the draw is constant. An AFCI will quickly trip. If the short is intermittent, the conventional breaker will likely not trip - but the AFCI will. If you have a 200A dead short, the conventional breaker will trip quickly.)
So, other than the cost, there doesn't seem to be a "downside" to AFCIs - they protect better than other breakers, even if they aren't perfect.
The only concern I have heard is false tripping when they are improperly applied. Bill mentioned some other concerns - I'd still like to hear about those.
I still haven't been able to find the article I saw previously.
A couple of points about AFCIs, though:
1. They will trip at least as fast (generally faster) than a conventional breaker for a fault that will trip a conventional breaker
2. They will protect against ground faults at least as well as a GFCI.
Don't mean or want to start a fight, but the above statement might not be true according to everything I have heard. Gfci s and Afci s are different devices doing (or intended to do) different jobs.
They will protect against ground faults at least as well as a GFCI.
Don't mean or want to start a fight, but the above statement might not be true according to everything I have heard. Gfci s and Afci s are different devices doing (or intended to do) different jobs.
My understanding is that AFCIs incorporate a GFCI. What have you heard different, and any further information on that?
"2. They will protect against ground faults at least as well as a GFCI."NO!The both detect unbalanced currents between hot and neutral.BUT, the AFCI is set to trip with an 30 ma difference. A GFCI to trip with a 5 ma difference.The AFCI is designed to detect deterating insulation and not for personal safety. A person can die with 6 ma."3. They will trip on moderate overcurrents and arcing, which conventional breakers will not. (Conventional breakers require sustained overcurrent or massive overcurrent to trip. So, if you have a 15A breaker and a weak short that is drawing 20A, a conventional breaker MAY eventually trip, if the draw is constant."Neither the AFCI or conventional breaker will trip.An AFCI requires a 70 amp arc signature before it will trip."So, other than the cost, there doesn't seem to be a "downside" to AFCIs - they protect better than other breakers, even if they aren't perfect."The first problem is false sense of security. A loose plug, a worn cord, a warm receptacle - it is easy for some to say "I take care of it later" while think to themself that it is OK in the meantime because of the AFCI. While sometimes might not happen until the problem becomes a fire. One that is not detected by the AFCI.Also it reduces the likelyhood that the HO will look at alternatives protection. Sprinklers, whole house alarm systems, extenquishers, etc.
I really don't think this is the place for another re-hash of the "Great AFCI debate." They exist ... NEC will call for them more and more ... and localities will disregard. Remember, it is the locality that IS the law, NOT the NEC- which is but a dream document endorsed by elites at obscure hotel conventions. The NEC might be a useful yardstick ... but one "complies" with the law, not a 'model.'
And. alas, I am not aware of any AFCI devices on the market ... even though the NEC does have some provision for them.
On the other hand, GFCI's have had a couple decades to work all the bugs out. It is safe to say that they are proven. Though not, strictly speaking, required in a finished basement, I am inclined to say "why not?" The additional cost is really quite minor.
And. alas, I am not aware of any AFCI devices on the market ... even though the NEC does have some provision for them.
They are readily available at any box store or electrical supply store in the US. They have been available for the last 5 years or so. Eaton makes them, other suppliers do, too.
Funny, I had to order mine. And this was at a dedicated electrical supply house.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
I think we're getting hung up on terminology. In electric work, a "device" is something like a receptacle or switch .... a breaker is not considered a "device." I agree that AFCI breakers have been available for as long as five years. "Devices," however, were not allowed in the 2002 NEC, and allowed only with severe restrictions in the 2005 NEC.
Other than the expense, is there any reason why one would not want to install an arc fault interrupt breaker?
Seems to me that in an older house (like cloth-covered wiring with substandard installation practices) it might save some property and lives.
In new houses it might do the same. A friend of mine just lost his new house. It seems his imported big-box bedroom lamp had some trouble between the metal tubing and the wiring. An arc-fault breaker would have probably stopped the problem before it turned into a fire. Alas, someone chose to save a few bucks, and this house is now an unpleasant memory and an ongoing insurance claim.
Why there was a new house built with no arc-fault on the bedroom circuit, I don't know. When did that law go into effect?
Other than the expense, is there any reason why one would not want to install an arc fault interrupt breaker?
Not really, in my experience.
The only real concern I have heard (other than cost) is that they could "false trip" on motor circuits, like a GFCI. However, Eaton asserts that their AFCIs perform the GFCI function electronically rather than with a transformer and therefore do not have this issue.
GFCIs tend to false trip on motor circuits. A GFCI is generally implemented as a toroidal sense transformer with a secondary
http://www.codecheck.com/gfci_principal.htm
When current above a threshold is sensed on the sense coil, the GFCI trips. The problem is that motors generate large current spikes, particularly on startup and under heavy load, and that can cause false tripping on GFCIs.
In contrast the AFCI is implemented with electronic circuitry that general relies on digital signal processing techniques rather than a transformer to detect ground faults and arc faults. The claim is that the algorithm is sufficiently sophisticated that it is immune to false tripping due to motor spikes. However, I have not tested or analyzed AFCIs for this condition, so I have no experience to support or refute this particular claim.
"Why there was a new house built with no arc-fault on the bedroom circuit, I don't know. When did that law go into effect?"The 1999 first had them required, IIRC in 2000. But only for bedroom receptacles. The 2002 expanded that to all outlets in the bedroom.But the NEC is not law.The only thing that is law is what the local community adopts. Not only which version of the code, but also they make local admentments.For example I looked at the only city codes for one small community near Chicago. They where still on the 1993 NEC, but modified it to limit wiring systems to conduit and AC only for limited applications.One near by city to me as adopted the current codes except the AFCI section. Anohter one has adopted the 2005 IRC (which includes the 2003 NEC for the residential parts), but modified so that the GFCI requirements read like the 1996 NEC and also no AFCI's."A friend of mine just lost his new house. It seems his imported big-box bedroom lamp had some trouble between the metal tubing and the wiring. An arc-fault breaker would have probably stopped the problem before it turned into a fire."Might not. Was it a series arc or a parallel arc?" Alas, someone chose to save a few bucks, and this house is now an unpleasant memory and an ongoing insurance claim."What would that money have done with installing a whole house sprinker system?If that lamp was in the living room then the NEC requirements would not have helped. Nor would if it was a series arc.Now, the proposal is that starting in 2008 all 120v branch circuits will require series arc AFCI's. Since they are not even availalbe then I am guessing at a cost of $40/circuit. Probably end up with $800 to $1200 per house.In new construction would that pay for most, if not all, of a whole house sprinkler system using a PEX system?(But note that some codes require steel pipeing and each job engineered and other requirments that would increase the cost many times and reduce the probability that sprinkler system be installed).Also with the requirement that ALL branch circuits be AFCI that there will be a big push to keep the number or circuits to the absolute minimum that the code will allow. Reducing the effectiveness of the electrical system."Other than the expense, is there any reason why one would not want to install an arc fault interrupt breaker?"False trips. Don't hear as much about them now. But with the still un proved series arc AFCI there is still a very high probablity of a false trip. Too many false trips and the AFCI get pulled, OR WORSE.
What about brush and commutator motors? Will the arcing there trip AFCI's? If so, shop vacs, sewing machines, sawzalls .... Lotsa things will be tripping them.
-- J.S.
The only currently available AFCI's detect parallel arcs. Those have to spike UP to 75 amps to trip. They should not have much problems with motor brushers.The 2008 code proposal calls for COMINATION AFCI's. That includes series arcs of 5 and 10 amp levels. Lots of questions about whethe they have have problems with brush style motors and possible even switches that arc.
The classic Mike Holt demonstration [as outlined in his Dec 9, '02 newsletter] showed the receptacle heated up to glowing before the AFCI tripped. A regular breaker in a similar situation did not. Note however, that a GFCI was not tested. My hunch is that the sole active mechanism of an AFCI is the ground fault detection.
Personally, I think AFCIs are a bunch of balogna. This is one of the greatest marketing schemes ever. You want to sell a product -- get a law passed requiring everyone to buy it.
If the receptacle starts gowing and melting, the the AFCI is not detecting the arc that started this. Perhaps if some heat sensing device were located in the receptacle that would melt or set off an alarm, this would be cheaper and more reliable.
~Peter J. Michael
Yea, I was looking at the 2006 IRC today and noticed that only combination AFCIs would be allowed after maybe jan.2008.(very unusual to see a code requirement that does not go into effect immediatly) Currently "feeder" and "combination" AFCIs are allowed.
I have no clue what they are refering to. What are the AFCIs installed as overcurrent protection that I see all the time considered? What is a feeder?
Since all new home construction (ok, most new homes) is going to be affected, this might be a big deal
"I have no clue what they are refering to. What are the AFCIs installed as overcurrent protection that I see all the time considered? What is a feeder?"They are branch circuit/feeder types. IE they only detect 30 ma leakage current and parallel arch that spike upto 75 amps.A feed is what exists from the service entrance equipment and final branch circuit overload device.IE, it the circuit fromthe main panel to a sub-panel.The proposaled 2008 code require not only the combination type, but also on ALL 120v branch circuits.I am guessing that a well wired modern 3-4 bedroom, 2-3 bath, 1800-2500 sq ft house that would be 20-30 breakers.
I was trimming out a room in my basement and my miter saw blew the 20A AFCI every time.
The cost is actually a huge factor. Regular breakers were @ $10, the AFCI's were $30- $40. Not to mention that I had to throw away my existing breakers to replace them with AFCI's. It seems that they don't take time or cost into consideration when coming up with new codes.
I used to be a firefighter and I think that when they finally come up with a code to address every possible cause of electrical fire, they will realize that electricity didn't cause as many fires as they thought.
The only currently available AFCI's detect parallel arcs. Those have to spike UP to 75 amps to trip.
That conflicts with the information Eaton provides on their products.
Why do you keep making up this stuff.From the link that YOU POSTED.http://www.eatonelectrical.com/unsecure/cms1/RE00402005E.PDF?GXHC_GX_jst=c7014444662d6164&GXHC_JSESSIONID=ced5761ad88149efPage 25 shows a .Dual-ListedÆ UL 1699 and UL1053 breakers.Look at the drawing. It shows a 30 ma ground fault sense circuit. Much too high to be used for personal safety.They also make a dual AFCI and GFCI (5ma) which they also show. But that is not common and most AFCI's don't have that feature."The only currently available AFCI's detect parallel arcs. Those have to spike UP to 75 amps to trip.That conflicts with the information Eaton provides on their products.'Again from the link that you posted.
"The current waveform is sinusoidal ùas it would be without the glowing contact series faultù
and the glowing contact is undetectable, as is true for all series faults (see Appendix I) since all
involve current flow through a restrictive layer of either copper or aluminum oxide."SERIES FAULTS ARE UNDETECTABLE.Then is goes on to add;"The faultÆs high temperature can melt both the wire and receptacleÆs insulation, ultimately
creating either an arcing or a ground fault."The heat generated from the series arc damages the insulation and which in turn MIGHT cause a parallel arc or ground fault BEFORE the house catches fire."1. Arc-fault sensing circuitry (A) that distinguishes between a safe, normal current and a
hazardous arcing fault and trips accordingly. This new breaker protects against:
- High energy arcing faults caused by insulation damage, and
- High-resistance-contact series faults that PROPAGATE from series to high-energy
arcing faults, and are caused by, for example, aluminum wiring connections,
glowing contacts, hot plugs, or broken conductors.".
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Why do you keep making up this stuff.
Probably because you mistake the FACTS I post for something I made up, since you clearly do not understand GFCIs or AFCIs.
What type of "non-computer related" engineer are you?
Bill is an EE.
CAP is a master electrician that writes articles for FHB.
No disrespect intended, but over the years these two guys have helped a lot of us understand electrical theorey and practical application.
Dave
What type of "non-computer related" engineer are you?
Bill is an EE.
Bill has previously asserted he is NOT an engineer - he isn't licensed, so he may not legally refer to himself as an engineer. I have encouraged him to contact his local licensing board, since he disagrees with the law, but he has apparently not done so.
CAP is a master electrician that writes articles for FHB.
That's interesting information - I didn't know that. I will say I find most of his posts informative and accurate.
No disrespect intended, but over the years these two guys have helped a lot of us understand electrical theorey and practical application.
That's fine - and I don't really have a problem with the information CAP posts. As I said, I find it helpful and generally on-target.
Some of the "head butting" is probably due to differences in perspective and experience. The classic conflict in EE is the technicians vs the engineers. The techs think the engineers are idiots, the engineers think the techs are short sighted, because they don't understand the theory and don't understand the "why" of what they do.
Since you asked nicely, my experience is 30 years work as an Electrical Engineer. I was involved in the development of the first AFCIs, but also have a lot of experience designing electrical test equipment. While much of my recent experience has been in development of residential and commercial power products for a major manufacturer, my prior experience includes consumer electronics, industrial controls, and less public work. I have even been on the NEC review panels. FWIW, most US residents have a product in their home that I designed or hold a patent on.
Though I still do "real" work on the side, my primary job now is as college professor at an ABET accredited tier 1 research institution. I have written a couple of textbooks, but mostly these days I try to teach 22 years olds how to become engineers.
Thanks for asking.
"Bill is an EE.Bill has previously asserted he is NOT an engineer - he isn't licensed, so he may not legally refer to himself as an engineer. I have encouraged him to contact his local licensing board, since he disagrees with the law, but he has apparently not done so."I have never said that I AM NOT AN ENGINEER.What I have said repeatly that I am not Professional engineer and I don't hold my self out as one.As I have said I have an BEE, MSEE, and post master course work.And I do engineering work that is covered under the industrial exemption.And I never said that I disagree with the laws.You have repeatly made misleading statements about this.Just the same that you have gotten everything else wrong in this thread.Anyone that wants to can go back and read it and look at all of the claims that you have made.Then where they have been corrected.And when corrected you have never offered any source of information that shows that you are correct..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I have never said that I AM NOT AN ENGINEER.
What I have said repeatly that I am not Professional engineer and I don't hold my self out as one.
Bill, we have been through this before. I'm sorry you don't like the law, but the law is the law.
"not a Professional engineer" = not an engineer.
By law in the United States, the term "engineer" refers to a licensed professional engineer - so either one is licensed, or it is illegal to call oneself an engineer. The SOLE exception is the so called "industrial exemption", where a company that manufactures a product is permitted to refer to employees as "engineers", provided they don't perform "engineering work" such as stamping drawings or doing work that affects public safety.
Most of us are just here to help others. Just because others disagree with you or have a different perspective doesn't mean they are wrong. Maybe they just have more applicable experience.
And yes, I have noticed you don't like to be corrected, and that you don't like to acknowledge the sources of information I have posted to document the facts I post.
If it's that important to you and your ego to think you are right, go ahead and think that. If you are that high strung and stressed, I sincerely hope you don't suffer a heart attack or other stress related illness.
To everyone else, it's wise to ALWAYS be cautious in applying information from internet boards. You can't really know what qualifications a person has, and there are a LOT of self proclaimed "experts" posting incomplete or misleading information. I wouldn't want to risk my life applying something I read on a bulletin board.
Even the magazines get it wrong sometimes - not everything you read in the pages of our favorite magazine is accurate information, or will be the best choice for your situation. The magazine is written by the readers - and there have been a couple of notable instances were incorrect information was published by another such magazine that had serious consequences.
Don't get me wrong, boards and magazines can be a great source of learning and information, but they can never take the place of a contractor or engineer who can look at your situation directly.
It is time to put this "engineer as title means Professional Engineer" debate to an end.Engineer in a title does not mean one is a licensed Professional Engineer. It means the Engineer works as an Engineer, but without a license, one cannot use the words Professional Engineer.As proof, go to these US Government Websites for job listings titled Engineer. Nowhere under requirements is a Professional Engineer license required! http://jobsearch.usajobs.opm.gov/getjob.asp?JobID=54463715&AVSDM=2007%2D03%2D02+01%3A10%3A27&Logo=0&pg=2&FedEmp=N&sort=rv&vw=d&brd=3876&ss=0&FedPub=Y&q=Engineer+DChttp://jobsearch.usajobs.opm.gov/getjob.asp?JobID=54619828&AVSDM=2007%2D03%2D06+10%3A04%3A46&Logo=0&FedEmp=N&sort=rv&vw=d&brd=3876&ss=0&FedPub=Y&q=Engineer+DChttp://jobsearch.usajobs.opm.gov/getjob.asp?JobID=54395898&AVSDM=2007%2D03%2D03+00%3A00%3A46&Logo=0&FedEmp=N&sort=rv&vw=d&brd=3876&ss=0&FedPub=Y&q=Engineer+DCSorry about the long URLs.So, the US Government has employees who are Engineers and are not required to hold a PE license.If you think this is just a Federal Government exemption, look at any municipal job listing website. PE required is rare. There is usually a pay differential for having a PE, but not a requirement.If this is the industrial exemption you speak of, it is a pretty broad class of engineers, and therefore negates your statement that the law is "not a Professional engineer" = not an engineer."
Frank DuVal You can never make something foolproof because fools are so ingenious.
So, the US Government has employees who are Engineers and are not required to hold a PE license.
Yes, that's a point of contention, since it is state law that requires all engineers to be licensed, but federal law governs US government employees (and takes priority over state law, per the constitution).
In my state, it's an uneasy truce - as long as the government "engineers" do ONLY work under federal law, the state can't do much. But let the Core of Engineers come in to do work on a building, for example, that is subject to local building codes, and they won't approve it without a P.E. stamp.
So I guess there are really two exceptions - the federal goverment titles folks engineer because they can, not because it is allowed, and then the industrial exemption.
"And yes, I have noticed you don't like to be corrected, and that you don't like to acknowledge the sources of information I have posted to document the facts I post."In fact, for any want that wants to go back through this tread and others, I have acknowledge the sources that you have posted and used them to show where they disagree with your claims.THE SOURCES THAT YOU HAVE POSTED DISAGREE WITH THE CLAIMS THAT YOU MAKE."If it's that important to you and your ego to think you are right, go ahead and think that. If you are that high strung and stressed, I sincerely hope you don't suffer a heart attack or other stress related illness."On the contrary seeing what kind of wacky thing you are going to post next is great stress reliever.Speaking of ego, why did YOU delete message 39 where you claimed """Sorry, 5 mA is more than enough to electrocute someone. It takes less than a milliamp to electrocuted someone, under the right conditions. Ask a cardiologist.""after I challanged that?All you had to do was to admit that you where wrong.I wish I knew what was in #51 and #53 that you deleted..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Speaking of ego, why did YOU delete message 39 where you claimed "
""Sorry, 5 mA is more than enough to electrocute someone. It takes less than a milliamp to electrocuted someone, under the right conditions. Ask a cardiologist.""
I wish I knew what was in #51 and #53 that you deleted.
That's really odd - I haven't deleted any messages in this thread. I'll have to ask the mods about that. Not sure if #51 and #53 were mine, or not.
And thanks for reposting the quote above for me - save me typing it in again. As we have discussed, under the right circumstances, 1 mA or less is enough to electrocute someone, and 5 mA is certainly sufficient, under the right circumstances.
Not common, but it can happen. If it were common, the threshold for GFCIs would have been set lower - it's a balance between practicality (i.e. false tripping) and safety.
"And thanks for reposting the quote above for me - save me typing it in again. As we have discussed, under the right circumstances, 1 mA or less is enough to electrocute someone, and 5 mA is certainly sufficient, under the right circumstances."You never indicated what the "right circumstances where".And as I pointed out, with messages that referenced published studies, the give much higher numbers.The only place that 1 ma might come in is during surgery.And even if it is true, it has nothing to do with this discussion.Just another red herring that you have thrown out..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
And as I pointed out, with messages that referenced published studies, the give much higher numbers.
That's one of the problems with searching for research papers or studies - often they use terminology that isn't common or expected, and the search engines aren't smart enough to figure out "similar" words.
One term commonly used in the papers for low current and low voltage electrocution hazards is "microshock".
And as I have said before, there doesn't seem to be a consensus on minimum required current for absolute safety, or even practical minimums.
Keep in mind, too, that I am a researcher. Everything is shades of gray, rather than the "black and white" that engineers often prefer. The only absolutely safe current is 0. However, I feel safe with GFCIs that trip at 5 mA, in most cases. If I'm in the hospital, taking a bath, with a catheter or drains in place, though, I would be very, very afraid if the only protection was a normal GFCI.
Anyway, here are a couple of articles:
http://www.bassengineering.com/microsho.htm
http://en.wikipedia.org/wiki/Electric_shock
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10641944&dopt=Abstract
You and all of your links agree that 5 ma is a safe limit for personal protection from GFCI's.And since we are talking about homes and not medical facilities why bring up "less than 1 ma". It does nothing, but add confusion to the discussions..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
"Probably because you mistake the FACTS I post ..."Give a link to source that validate the FACTS that you claim about how AFCI's and GFCI's work..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=83852.1"From: woodturner9 Jan-8 11:00 am
To: wegotrocks (2 of 18)
83852.2 in reply to 83852.1 A GFCI should trip when there is sufficient imbalance between the current flow in the neutral and hot, or when there is current flow in the ground above a threshold.NEC does allow use of ungrounded GFCIs - they still protect the user by tripping on unbalanced current flow between the hot and neutral (indicating the current is finding another return path, such as through the ground).Your tester should trip a GFCI, even if the ground is not connected."I am still waiting for you to show me a GFCI tester that will work without a ground connection.http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=83852.1"From: woodturner9 Jan-8 2:06 pm
To: BillHartmann (5 of 18)
83852.5 in reply to 83852.4
"Your tester should trip a GFCI, even if the ground is not connected."How?As I explained, a GFCI responds to either an imbalance between the hot and neutral or a current flow in the ground wire (or both). In the OPs configuration, the imbalance is what identifies the ground fault (because there is no "real" ground).A tester works by creating this imbalance, which will cause the GFCI to trip. There are several ways to do it, but the point is that the tester creates the imbalance that simulates a ground fault.Nothing wrong with using the 'push to test' button on the GFCI, though. I wonder why the OP is not just doing that. You need the tester to check downstream receptacles, but the GFCI itself is easily tested with the button."Without a ground connection how is the tester going to create an inbalance?.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Isn't having an imbalanced operator enough?
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
I am still waiting for you to show me a GFCI tester that will work without a ground connection.
I have previously posted links to such testers, and even explained in layperson's terms how such testers work. It appears you don't want to acknowledge that because you don't understand it.
Perhaps you should leave these discussions to those familiar with the topic.
"I am still waiting for you to show me a GFCI tester that will work without a ground connection.I have previously posted links to such testers, and even explained in layperson's terms how such testers work. It appears you don't want to acknowledge that because you don't understand it."You have never posted a link to a 2 wire GFCI tester that will work on an ungrounded receptacles.And in fact when I mentioned that it would require a 2 wire device that a different current level one terminal than that at the other terminal you agreeded with me."Perhaps you should leave these discussions to those familiar with the topic."In all of these discussions I have have not seen anyone else that disagrees with me.But many of your statements have been questioned..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I would welcome a link to a GFCI tester that requires no ground connection. I have not found one in my Google searches.An explanation of how it works would be nice also. Do you have a link to the earlier post?Frank DuVal You can never make something foolproof because fools are so ingenious.
An explanation of how it works would be nice also. Do you have a link to the earlier post?
Here are two. Still looking for the others, having trouble with the search engine.
http://forums.taunton.com/tp-breaktime/messages?msg=85524.150
http://forums.taunton.com/tp-breaktime/messages?msg=83852.18
OK, you got me confused, and I have an EE degree. To convince the GFCI that there is a current imbalance, some current must go somewhere else -- Kirchoff's gonna be upset otherwise. So you need to somehow "hide" 5ma of current somewhere inside the tester, so that it comes in one side but doesn't go out the other. IOW, electrons have to actually accumulate inside the tester.Now I'd agree that you could do this with a big, hairy capacitor, but you'd still need somehere to tie the other end of the capacitor.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
So you need to somehow "hide" 5ma of current somewhere inside the tester, so that it comes in one side but doesn't go out the other.
It's a different way of thinking about the world, essentially. Conventionally, we like to think about insulators as having 0 current flow, and conductors having 0 resistance. In practice, however, everything is both a "conductor" and an "insulator" - everything has impedance, and everything has some current flow.
However, the connection to true earth ground is VERY low current, even for such a tester. That's where the op amp comes in. The op amp senses the voltage difference to true earth ground, requiring only nA to do so - well within the "leakage" normally seen in the real world. Another op amp offsets the voltage and provides a low impedance output, so it can drive enough current to trip the GFCI. This output is at or below earth ground, so that current will flow from the neutral potential to this point.
Conceptually, it's like a resistor divider, with the highest voltage R1 connected to the hot, and the other side of R1 tied to R2 and R3. R2 goes to the neutral and R3 goes to the below ground reference point. Thus the current out of the hot is split between the neutral and the local "pseudo ground" reference return.
Is that a more clear explanation? It's sort of the same concept as no-contact voltage detectors.
Having said all that, the links I posted previously for some of these products don't seem to work anymore. I did some calling around, and many of these devices are no longer on the market. The lab versions are still available, but they are expensive and bulky, so not something an electrician is likely to use. I talked to the engineering manager at one (former) manufacturer, and he said that they weren't selling well so they dropped the product. So I'm not sure you can still even buy the "portable" versions of these testers, which may explain why a lot of folks here don't seem to know about them.
Edited 3/12/2007 4:14 pm ET by woodturner9
Where does it get "true earth ground" from? If you're using the operator's hand, that's a third terminal, no?
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Where does it get "true earth ground" from? If you're using the operator's hand, that's a third terminal, no?
There is a low current "leakage" path to true earth ground, essentially through the air. It does not require the operator to have his hand on the tester.
And you're able to source 5ma through that for 1/120 of a second? What sort of voltage do you have to produce?
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
And you're able to source 5ma through that for 1/120 of a second?
Yes, though usually you integrate for a period of time to charge an inductor.
So what kind of voltage gets generated? Enough to zap the guy holding the thing?
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
So what kind of voltage gets generated? Enough to zap the guy holding the thing?
I'm not sure I'm fully understanding your question, since I don't seem to be answering it.
These are devices for testing 120 VAC, so yes, that is enough voltage to injure someone. However, the case is insulated, so the user is not in contact with the conductors and thus is protected.
OK, the way I picture this, we have a device that consists of a coil across hot and neutral, with an electronic switch of some sort on one end. On the switched end the coil is also connected (possibly via capacitor) to the metal case (or some other mass of metal in the device), which is insulated from user contact.To trigger the thing, the switch is first closed for about a quarter cycle, then opened near peak. Substantial (to a GFCI) current will then flow through the coil and charge the capacitor whose "plates" are the metal case and the rest of the world, separated by the outer plastic case.No fancy electronics are required to make the thing work (in fact, this scenario simulates some false trips due to motor switching, etc), but some sort of control circuitry is needed to regulate the fault current, either by estimating the appropriate charge/discharge parms in advance, or by dynamically regulating current.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Looks like we've got hung up on semantics. To get the right answer, you need to ask the right question."Combination Devices"
When speaking of arc fault detectors, they mean ones that will detect arcs, whether they be in "series" (as with a loose wire) or "parallel" (as from a receptacle screw to the ground wire). This is different from devices that are carry both AFCI and GFCI ratings. The NEC wants these "combination" breakers, manufacturers keep promising them, but there is still doubt if they will ever exist.How a GFCI works
A GFCI is based upon the simple idea that current going 'out' the hot wire should exactly equal the current coming back 'in' the neutral wire. The device measures this current; if the difference is more than 5mA it's supposed to trip.
Simple plug-in testers make the thing trip by using the ground wire as a 'drain,' so to speak. Not all the current returns in the neutral wire, and the device trips.
The test button on the receptacle has access to the wiring before the internal sensors; so the test button will work, and the GFCI will work, even if there is no ground pate (or wire)."Engineer"
Lots of folks get to call themselves 'engineers,' including the folks who drive trains. It is only the term "professional engineer" that is reserved by law to those who take the PE exam. FWIW, other types of engineers -some, not all- have their titles reserved by different statutes. "Structural Engineer" is one that comes to mind.
a) The metal case forms a capacitor to the ground. that capitor to ground is the 3rd terminal and thus violates only 2 terminal requirement.b) there would be no way to calibrate such a capacitor so the amount of current would be variable and not usefull to verify proper operation.The reminds me of a professor that I had in grad school. Don't remember at all what the course was about. But the he came up with such rediculousridiculous examples that some of the students aske for something more practical.So the next example was the deflection circuit in a CRT with 25 FARADS between the sweep plates..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I think you could dynamically "calibrate" the device to reasonable accuracy, using one of the techniques I discussed. But I agree that it's technically a 3-terminal device.I remember seeing a cap measured in farads at Wright Patt, sitting on a loading dock as scrap. About the size of a 55 gallon drum, IIRC.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
There are (where) some reasonable sized fractional farad (1/4, 1/2) caps available. Rated about 3 volts.Used as short time standby power on electronic equipment.That was before the days of low cost electrically reprogramable memeories..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I got the impression the one I saw was used for some sort of electromagnetic forming experiments. There were also some really honkin' coils laying out there.(Wright-Patt was always a good place to go exploring the back docks where the "trash" was left. All sorts of good stuff to be found, especially if there was an inspection imminent.)
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
I am still waiting for you to describe a device that will verify ability of an ungrounded GFCI safely protect people.Ungrounded - that means that there is no ground available.
Protect people - that means that you have a difference in current of 5 ma between the hot and the neutral..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
It's called a bathtub and a toaster. (Hair dryer won't do because of the integral GFCI.)
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
That is not reliable.With plastic drain pipe the tub won't be grounded..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Hi Bill,I really appreciate your insights re: AFCIs... we had a whole bunch installed when we redid the house and I didn't know nuances between the two beyond the arc-fault feature in AFCIs. IMO, it's worth it to segregate lighting and receptacle circuits throughout the house. The code may or may not require this in all rooms, but I think it's a very good idea. Blowing out a circuit breaker is bad enough, groping for a path to the panel in the dark is less than fun. I also went further than code required on the wiring to the receptacles. They're all fed by 12GA wiring, with 15A breakers at the box. All "commercial" switches, receptacles, etc. that hopefully will require a lot more use before they wear out than our family can put them through.We also installed a fire-sprinkler system. Here in MA, that is getting more than a bit difficult because the insurances now require a separate rider for sprinkler installers. Thus, most plumbers, etc. have left the business. The commercial guys cannot be bothered, they make so much money doing hard pipe that they don't want to even look at plastic-based distribution systems. Where the national fire protection advocates claim that protection is possible to install fire sprinklers for new construction at around $1.5/ft^2, we counted ourselves lucky to get it in at $4/ft^2 (several "no-quotes" exceeded $6/ft^2). In areas where these sprinklers are mandatory in all residential construction, prices may be less expensive than up here in MA, where it's not (under 12,000ft^2, not more than 3 units in a home, etc.).However, depending on the required system (fire line to the house? storage tank in the basement? Pressure pump? What kinds of heads? etc.) the costs will easily exceed the additional burden that AFCIs impose. Yet, I agree with you that fire protection via sprinklers is probably a better investment than relying on AFCIs to save the house. After all, there are many sources and causes for fire, not all of them originate in the electrical system and not all of them would be prevented by the whole-sale adoption of AFCIs in all non-bathroom circuits. That said, our permanent CoO was delayed by over 8 months because the fire prevention services office attempted to read things into the code that weren't there (to the consternation and amusement of the building code review board).
I, too, kept lights separate from receptacles. I also checkerboarded two lighting circuits, so if you lose the light in the bedroom, you can still see by the light from the bath or the hall, or vice versa. Expensive AFCI's being required would make that design harder to justify.
-- J.S.
Dang it. Now I'm going to have to buy two more AFCI breakers so I can checkerboard them. THANKS for passing on that good idea. Jerk. ;)
<grumble>Stupid good ideas make me do more work</grumble>Rebuilding my home in Cypress, CA
Also a CRX fanatic!
> Why there was a new house built with no arc-fault on the bedroom circuit, I don't know
Do you know for sure that it didn't have an AFCI? If the faulty contact was made quickly and maintained, like if a piece of zip cord got pinched between some steel parts, there might not be a detectable arc. Nor would there be a ground fault in that case.
If the third line of defense, the overcurrent protection, gets short changed in these AFCI's, they may be less safe than the breakers of long ago.
-- J.S.
http://ecatalog.squared.com/techlib/docdetail.cfm?oid=09008926800aa627
Here is the cut sheet on the Sq D QO and Homeline AFCI.
"Arcs to ground and
ground-fault current
will be interrupted
at 30 mA or more."
"Arcing faults will
be interrupted
when they
exceed 50 A."
"The Square D Arc-D-tect AFCI detects an arc fault by
analyzing the signature of the arc. The AFCI is UL listed as
the ôBranch/Feederö type. This means that it takes action against
high-energy, hazardous arcs.* The UL standard provides for arc
detection between hot and neutral conductors at 75 A rms or more.
The Square D AFCI will open at 50 A peak arcing current.
It also detects and opens on as little as 30 milliamps rms of
arcing current to ground."
Yes, they have a GFCI function, BUT IT IS A 30 MA, WAY TOO HIGH FOR PERSONAL PROTECTION. AS I HAVE SAID REPEATEDLY.
BUT NOT AT 5 MA.
"Sorry, 5 mA is more than enough to electrocute someone. It takes less than a milliamp to electrocuted someone, under the right conditions. Ask a cardiologist."
No, 6 ma is the general reconized limit for "normal" conditions. That is not connected to internal body parts.
Junkhoud has posted the studies several times.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Bump to JunkHound..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=35021.37&search=y
"
From: junkhound 9/27/2003 1:51 am
To: SamT (37 of 42)
35021.37 in reply to 35021.35
"1ma at 500,000vac will kill"
For 10 cents I'll take 1 mA from 500 kV (or any other voltage) anyday, every second.
Sam, you usually have a very precise and technically correct response, but the above is bogus. 99% of humans will not even feel 1 mA.
However, 99.9999% of humans have a lower skin resistance than R=500E3/E-3, so subjectively, a 500 kV powerline is nearly always lethal 'cause the current is always going to be over an amp for more than a few micorseconds.
5 mA for 5 seconds is lethal to 0.5% of people, according to Dazeil's (sp) experiments in the 1950's (still the main source of electrocution data).
Also, if the shock is short (less than a second) data shows that the electrical shock needs to hit the heart during the T wave to be lethal (fibrillation onset). Somewhat of a lottery there, like a group of people getting hit by a lightning stoke and only some die instantly.
PS- would PETA ever croak about Dazeil, he fried literally thousands of sheep and pigs to get his data, as sheep and pigs have similar hearts to humans - you figure if democrat or republican 'hearts". <G>"
http://forums.taunton.com/tp-breaktime/messages?msg=35021.38
"
From: junkhound 9/27/2003 2:02 am
To: ALL (38 of 42)
35021.38 in reply to 35021.37
a couple of charts from a EE course I used to teach."
http://forums.taunton.com/n/mb/at.asp?webtag=tp-breaktime&guid=937EBC5F-DB3C-43B0-A090-91CDEE07CDF0&frames=no
http://forums.taunton.com/n/mb/at.asp?webtag=tp-breaktime&guid=3C8D8814-4C2B-45AF-A1E3-E8FD681112AE&frames=no
http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=77731.16&search=y
"From: junkhound 8/22/2006 10:24 pm
To: firedude (16 of 54)
77731.16 in reply to 77731.15
do some on-line research---- well, that and more ---
Thanks for the concern, but not to worry for my safety -- my test setup has 4 levels of fail-safe to keep currents below 20 mA.
Lot of what is on the open web is just regurgitation of 40 year old data and a little more recent data.
That is what this thread is about, requests for first hand experience.
I have read all of Dalziel's papers, most of Freiberger's, Biegelmeister's, Osypka's, Freisleben's and Fitzgerald's papers on the subject. Also have Reilly's book, "Applied Bioelectricity" which summarizes much of the present knowledge. Also have UL and BS and IEEE and IEC specification, etc, etc.
What I am most interested in are stories of "startle" reactions, of which Reilly's book devotes all of 1-1/2 pages out of 600. As much info on that reaction is already in this thead as anything else, except for the 1968 Smoot papers on experiments done on women for UL consumer appliance specification derivations.
FWIW, my feet to the ankles in salt water along with my hands are about 414 ohms, pretty constant from DC to 1 kHz, currents under 20 mA. 20 mA I canstart to feel tightening of forearm and hand muscles. All previous data says about 15 mA max, but that is only for hand to hand, so you can start to get an idea how limited real data is.
Dalziel electrocuted over 10,000 sheep and pigs form the 1930's thru the 1960's to get his fibrillation (electrocution data). Biggest samples to date for startle reactions are about 20 people, so you can see how the responses to this question on BT actually DO add alot to the overall knowledge base.
Should have gone to the fest with my test apparatus <G> "
http://www.allaboutcircuits.com/vol_1/chpt_3/4.html
"BODILY EFFECT DIRECT CURRENT (DC) 60 Hz AC 10 kHz AC
---------------------------------------------------------------
Slight sensation Men = 1.0 mA 0.4 mA 7 mA
felt at hand(s) Women = 0.6 mA 0.3 mA 5 mA
---------------------------------------------------------------
Threshold of Men = 5.2 mA 1.1 mA 12 mA
perception Women = 3.5 mA 0.7 mA 8 mA
---------------------------------------------------------------
Painful, but Men = 62 mA 9 mA 55 mA
voluntary muscle Women = 41 mA 6 mA 37 mA
control maintained
---------------------------------------------------------------
Painful, unable Men = 76 mA 16 mA 75 mA
to let go of wires Women = 51 mA 10.5 mA 50 mA
---------------------------------------------------------------
Severe pain, Men = 90 mA 23 mA 94 mA
difficulty Women = 60 mA 15 mA 63 mA
breathing
---------------------------------------------------------------
Possible heart Men = 500 mA 100 mA
fibrillation Women = 500 mA 100 mA
after 3 seconds
--------------------------------------------------------------- "
http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=58699.30&search=y
"From: junkhound 5/28/2005 8:03 pm
To: ALL (30 of 55)
58699.30 in reply to 58699.29
Sometiimes the ignorance spouted as knowledge is amazing.
Dan H's comments were good, some others acceptable, some are so totally BS it is appaling.
e.g as to bs: "People have been killed by 12V batteries" If anybody has documentation on this, it would be publishable.
Ok, ill agree that a 12V car battery dropped onto your head off a 3 story roof can kill you; however, the lowest DOCUMENTED case of electrocution was from 18vac. (Indemnity insurance report)
Someone else's comments about the capacitors in motor circuits are good to, there is at least one documented case of electrocution from an 120 vaac window AC where it was ungrounded and the short to case was from the cap to start winding connection, that gave about 370 vac via resonance to ground, enough to drive the 80 or so ma needed to electocute 1/2 of 1% of a normal population.
Also, you gotta get shocked during the T wave for fibrillation to start from low level (non-frying levels) currents. (got bit myself with 3kV 1A capability source 45 years ago and survived, kinda in a daze for 5 minutes)
For more factual info, do a web search on the original 1940 and 50's research by ChuckDalziel. "
http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=67781.1&search=y
"From: junkhound 1/1/2006 9:05 pm
To: ALL (1 of 5)
67781.1
There are occasional references to electrical danger (some factual, some hyperbole), the 3 attachments categorize those, charts from a class on High voltage taught on and off for the last 20 years.
Have other charts of person's hand-hand or hand-foot impedance at different 'sweat' states with unbroken skin*, as low as 5 kohms, so 120 V can give as high as 20 mA rms, which can cause loss of control, > 5 sec contact, and possible fatality in a low percentage of humans.
*if skin is broken or catheter in place, much lower - lowest documented case of 60 Hz electrocution is 18 vac according to Indemnity Insurance Co.
- Attachments follow -"
http://forums.taunton.com/n/docs/docDownload.aspx?guid=488F6150-67D2-4C83-9FF0-433B4D4E391E&webtag=tp-breaktime
http://forums.taunton.com/n/docs/docDownload.aspx?guid=D4E9FCB5-6ED0-4078-B1E7-04DF7D8AE904&webtag=tp-breaktime
http://forums.taunton.com/n/docs/docDownload.aspx?guid=0E908844-302D-4663-837F-B2F978697B5F&webtag=tp-breaktime
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
"Sorry, 5 mA is more than enough to electrocute someone. It takes less than a milliamp to electrocuted someone, under the right conditions. Ask a cardiologist."
Show me a "basic" GFCI (the kind installed in kitchens and bathrooms) that trip at less than 5 ma.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Easy, Bill, you got him pinned.
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