I’m adding a 27′ family room to the back of my house. It’s framed in and we had to have the electric meter (which was on the back of the house, in the way) moved to a temp pole. I ran the new 200 amp wire through the 2×6 wall of the family room to the back where the new meter will be situated. I am ready to have my new meter and dis-connect attached and have the power switched to the new meter. I also ran a heavy copper grounding wire in the same holes in the studs, from the spot where the meter will be, into the basement and over to the cold water line. My question is this: If I have foam insulation sprayed in the family room walls, will that have any effect on the copper ground wire, since it will essentually buried in the foam? I know the foam is supposedly flammable and I thought if there ever was a lightning strike or a blown transformer (both of which have happened) that the power surge in the ground wire might ignite the foam. Is this anything to worry about? Also, is the foam a fire hazard? I know blown cellulose is fire retardant, but the insulation value is so much better with the foam.
Thanks, Bob
Replies
I'm no electrician. And I don't know the answer to your question. Consider this a bump.
But while I'm bumping....
"I also ran a heavy copper grounding wire in the same holes in the studs, from the spot where the meter will be, into the basement and over to the cold water line."
It is my understanding that grounding to the cold water line is not appropriate. You need a grounding rod or two driven into the ground outside the house to which you can clamp the ground from the box.
But I could be wrong.
Rich Beckman
Another day, another tool.
"It is my understanding that grounding to the cold water line is not appropriate. You need a grounding rod or two driven into the ground outside the house to which you can clamp the ground from the box."There are too types of ground electrodes. The ones listed in the first part (underground water pipes, metal framing of structure where effectively grounded, Ufer ground {electrode buried in concrete footing}, and ground ring) and Made Electrodes.If you have any or all of the first ground they MUST BE USED.Typically a house might have a metal water pipe (has to be at least 10 ft long under ground) and for new construction a ufer ground.However, the water pipe ground is not allowed to be used alone. My guess is because of the possibility that it might be replaced with plastic in the future. Thus a secondary electrode is also required. A ufer, if available will do.If no ufer then a ground rod (made electrode) can be used. However, a ground rod can not be used alone unless it is tested (a special test) and has less than 25 ohms.Thus for houses, without a ufer electrode, the most common ground electrode systems are one metalic water pipe and a ground rod or if no metalic water pipe then two ground rods at least 6ft apart.Another "catch" is that if the water line is not 10 metalic underground, but the internal plumbing is metalic and thus does not qualify as a ground electrode the water pipe still is BONDED to the ground electrode system.
Bill -
I don't wanna highjack this post, but can you give a brief description of the function of lightning rods, and why you (I) don't see them anymore? I mean really, not just what the books say.
You the man!
Forrest
Thanks for your great reply yesterday! I am planning on using a minimum of one 8' grounding rod in the ground. I just didn't mention that in my original question. I was only trying to find out about fire hazards. I bought and read Rex Caulfield's Taunton Press book about wiring a house. It's fabulous! He says you should use several ground rods...several feet apart....and that they have to be in continually moist soil to be effective. That's in my plans. The water pipe in my house will be a secondary ground, like you mention.
Thanks alot! Bob
Do Not Ground to your water pipe... primarily or secondarily. A short can juice up the supply lines and that wouldn't be pretty.
The difference between stupidity and genius is that genius has its limits. -Albert Einstein
http://www.peteforgovernor.com
My impression is that you are not grounding TO the water pipe, you are bonding the water pipe to ground, as in grounding the water pipe. Perhaps it should be connected to the ground rod outside rather than to the ground in the panel.And my impression was that this applied to iron gas pipes also, though I don't see that being done very often.
"Do Not Ground to your water pipe... primarily or secondarily. A short can juice up the supply lines and that wouldn't be pretty."A short of WHAT to WHAT?And what does it mean to "juice of the supply lines"? I could not find any reference to "juice the line" in the NEC or anyother electrical reference.And exactly what is wrong with the supply lines (I assume you are refering to the water lines and not the electrical, but who knows) being "juiced up"? Why does the code require that metalic water pipes be bonded?Do you know what bonding is?What happens if the water pipe is not bonded and it gets "juiced up"?What is a ground fault current? And why is bonding important if you have a ground fault?Below is a message giving some information about ground electrodes and bond that I have already posted in this thread.--------------------"It is my understanding that grounding to the cold water line is not appropriate. You need a grounding rod or two driven into the ground outside the house to which you can clamp the ground from the box."There are too types of ground electrodes. The ones listed in the first part (underground water pipes, metal framing of structure where effectively grounded, Ufer ground {electrode buried in concrete footing}, and ground ring) and Made Electrodes.If you have any or all of the first ground they MUST BE USED.Typically a house might have a metal water pipe (has to be at least 10 ft long under ground) and for new construction a ufer ground.However, the water pipe ground is not allowed to be used alone. My guess is because of the possibility that it might be replaced with plastic in the future. Thus a secondary electrode is also required. A ufer, if available will do.If no ufer then a ground rod (made electrode) can be used. However, a ground rod can not be used alone unless it is tested (a special test) and has less than 25 ohms.Thus for houses, without a ufer electrode, the most common ground electrode systems are one metalic water pipe and a ground rod or if no metalic water pipe then two ground rods at least 6ft apart.Another "catch" is that if the water line is not 10 metalic underground, but the internal plumbing is metalic and thus does not qualify as a ground electrode the water pipe still is BONDED to the ground electrode system.
Another thing....
The grounding rod should be installed nearest the box, not the supply line.... IIRC
For lightning protection, add a separate grounding rod near the supply if it makes you feel better.
I'm no electrician... at all.... but I've heard things. Now just give these guys a few minutes to let me know if I've heard the right things.... lol
The difference between stupidity and genius is that genius has its limits. -Albert Einstein
http://www.peteforgovernor.com
Thanks for your reply yesterday. I, too, will have grounding rods on the outside, but just didn't mention them in my original question. Was your ground wire in the studs inspected and passed? What is your insulation in that wall? Fiberglass?
Thanks, Bob
Another 4 minute bump.
I never liked the idea of cutting outlet boxes into foam for the same reason. Light a little hunk of foam and see how long it takes to burn.
Beware. RFID is coming.
watch out for the cyanide based fumes...
can we spell dead....Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Thanks for your reply yesterday. I got a chunk of dry foam at a construction site and tried to burn it. I couldn't get it to burn at all. I used several matches and it only smoked a little and blackened a bit. Actually, I was quite glad! I had figured it would flame up instantly. It gave me more encouragement to use the stuff.
Thanks, Bob
Bob,
There is an obvious answer that is wrong and a more complex answer that is correct.. If you put a match to some foams they will burn or at the least give off a heavy smoke that is toxic..
However fire does require oxygen. take away the oxygen and the fire is out or won't start..
Buried in foam? the vulneable point is where it exits the foam and that should be in a box that is rated..
Is it perfect? absolutely not! However densepack celluloise isn't perfect either. The fire retardant can leech out, dust and other contaminants may still ignite, the exit point is still vulnerable. My solution to the dilema was to run all electrical inside armorflex or conduit..
Insulating foams, with the exception of a type that hasn't been made in a generation, all burn like rocket fuel. And, they all give off some very nasty smoke. This is why we sheath foam with gypsum board- especially if the stuff is being put in the ceiling.
That said... I don't care how big the lightning strike; the wire in the foam is less likely than the house itself being lit by the lightning.
As far as grounding, it is important to "ground" or "bond" the water pipes to the "grounding system." This is usually either a wire within the concrete slab, or a ground rod.
These grounding methods accomplish three things. First, should there be any sort of electrical fault, they give the electricity a good, easy path back to the panel- making it more likely tha the breaker will trip.
Secondly, they make sure that everything in the house is at the same "potential," that is, you won't have, say, 50 volts between the fridge and the kitchen sink. Finally, they help prevent an electrical charge from accumulating on the house- which is a necessary pre-cursor for a lightning strike.
In other words, "lightning protection" doesn't so much give the lightning a place to go, as it makes the house invisible to lightning.
Thanks for yesterday's reply. I got a piece of dry foam at a construction site and tried in vain to light it. I used several matches and all it did was smoke a little and blacken a bit. I was quite glad, actually, and it gave me more encouragement to use the foam. I will be using one or more 8' ground rods as well as the wire in the wall.
Thanks, Bob
You mean it didn't shoot into the sky like a rocket?
No, it wouldn't light.
Foams don't all burn like rocket fuel. It depends on the
type of foam, and the amount and type of retardant
contained.Phenol foam, which might be present in an existent installation,
merely chars when blasted with flame.Furthermore, just to be really, really pedantic, there are
a number of things in your interior which when burned, are even
more toxic than buring polyurethane. Wool, nylon and nitrile
are three that come to mind. And anyway, the burning urethane
that kills you is most likely going to be the urethane in the
foam cushions in your furniture, which was made in China to a
spec that didn't included retardant...
Thank you very much! I'm feeling better and better...and safer, about using it in my walls.
Bob
Bob,I saw a photo of a house that burned down before it was completed. The only part that survived was the section that was filled with sprayed polyurethane foam. The foam protected the framing in that one section.Sprayed polyurethane foam is a good, and safe product IMO.Bill
Great Stuff Pro gun foam is specially formulated to be a fireblock. If you are concerneced about electrical fire, you could foam the suspect areas with that then fill the rest with conventional insulating foams.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Thanks to you for the info. Great Stuff Pro gun foam is a brand name? In cans at the home center? Also, what is CRX?
Thanks, Bob
Hey Bob,Yes, it is good to check, but I think the retardant is government mandated. BTW, a CRX is a small sporty Honda car model. Paul restores them for fun, when he isn't testing screw-fastened framing connectors or remodeling his home.Bill
If your local HD has a Hilti outlet, you can get the gun there (I really like mine and it seems average price for the quality). I don't think HD carries the Great Stuff gun foam though. The Hilti foam is NOT a fireblock. You can find a place near you that carries it though if you do a web search.
A CRX is the most insanely great grocery getter ever made :)
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Edited 6/26/2006 11:49 pm ET by xxPaulCPxx
"Great Stuff Pro gun foam is specially formulated to be a fireblock."Are you sure?Now Great Stuff does make a specific fire "caulk" foam. But they also make saveral other foams and I don't remember seeing anything aboutthem being fire rated, but was not looking for that either.
Yes, I am... here is the link:
http://greatstuff.dow.com/greatstuff/pro/fireblock.htm
Fireblock
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Currently, GREAT STUFF™ PRO Gaps & Cracks is the only recognized alternative fireblock penetration sealing foam on the market. GREAT STUFF PRO Gaps & Cracks has been evaluated by the International Code Council's Evaluation Service, Inc. for use in residential construction.
Fireblocking is defined by the International Building Code as the use of approved building materials installed in concealed spaces to resist the migration of fire and hot gases.
GREAT STUFF PRO Gaps & Cracks is tinted orange to be more recognizable to building code officials.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
It's not a matter of being "pedantic," it's a matter of data... The standard by which insulation is tested for fire 'resistance' is the same one used for drywall, wood, ceiling tiles, etc. It is known as ANSI E-84, or "the Steiner Tunnel." EVERY foam tested under this standard - with the sole exception of urea-formaldehyde, which is no longer made- burns. It ignites fast, burns vigorously, and gives off lots of smoke. Even the ones with "retardants" in them. At the end of the testing, each material is classified as to "flame spread" and "smoke generated." Comparing these products fire behaviour to "rocket fuel" or "gasoline" is quite apt. I will concede that some foam products are sold with very low 'flame spread' ratings. This is due more to the nature of the test, than the fire characteristics of the material. Simply put, these foams, at the slightest heat, fall away from the test sample, to the floor of the "tunnel." There, they burn quite vigoriously. This is why such products will always have instructions explicitly warning against installation overhead, unprotected by drywall. Fire blocking agents are not tested in this manner. They are either tested as part of an assembly, or given a cursory spot-flame test. What this means is that a product might work fine as a fireblock, yet fail a flame-spread test miserably. And vise-versa. Don't get me wrong; I'm quite fond of foam insulation, in all it's forms. I just wouldn't dream of installing it without a good layer of drywall over BOTH sides. And remember... it was the use of foam as a gap sealer that directly led to the fire that almost destroyed a reactor at Brown's Ferry (1972, I think).... which in turn led to testing of fire-stop materials.
I'm not sure where you got "pedantic" from, I was passing along information I had gotten from the manufacturer of this product, after having it pointed out to me on this forum. He asked a question, and I answered it as best I could.
Out of curiosity, could you explain to me the differences between the ANSI E-82 and the ASTM E 136 testing?
Also, you say that ALL foam burns quite well in this test... but what about the primary fireblock material - 2x wood?
Tests for flame spread and smoke generated may be relavent for certain applications. Fireblocking is a system, however, and deserves to be tested as such. If a 2x4 with a copper pipe penetrating it sealed up with fireblock foam is tossed into a blast furnace, it's all going to melt of burst into flame in very short order. The fireblock didn't fail - EVERYTHING failed.
I may be only looking at partial information here though. Please give us more details on what you know here.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Is there a home version of this? I was looking high and low for a fire block rated expanding foam. I can't justify getting the guns. Well I can't deal with the cleaning part. Plus the guns do not seem to be very common here in Columbus and I don't want to have to do mail order for the small amounts that I need.
Plus the guns do not seem to be very common here in Columbus . . .
In addition to the guns, it's difficult to find the foam for the guns. I got the gun and a couple cans of Enerfoam from Western Tool, but all the other places I've checked around here only carry the straw applicator cans of the regular stuff. Plus, there are often sales on the straw cans which make it cheaper than the gun.
Can't beat the gun for control, though.
Supposedly the fireblocking version is available in both forms, but again, finding the right material in the right dispensing container seems to be difficult.
Don
ABC Supply in Columbus OH sells this product, $32 for the gun, $12 for the foam, $7 for a can of cleaner. If they don't have it in stock, it might take a day or two to get from their supplier - call them first to see.
The benefit for the homeowner (like you and me) is that the gun foam does NOT require cleaning after each use and CAN be used over and over again. Straw cans (besides not being a fireblock as far as I've seen) are good for one use only, and are very difficult to control resulting in alot of mess that is very hard to clean. At $5 a straw can, I really had to think if a spot reeeeeealy needs to be sealed to waste a whole can on now, or should I wait until I have another spot... then I would forget about the original spot.
The gun foam you can use to lay a little bead of foam down here, two weeks later a big bead there, three weeks latter another bead here, two months later you can seal a hole there... really, it becomes a MUCH more useable product. It doesn't take vary long for the gun foam settup to pay for itself. One $12 can of foam lasts a VERY long time. If you find you aren't using the gun over many months of time, you can unhook it and then run the cleaner through. That is the ONLY time you MIGHT have to use the cleaner, otherwise if you run out of a can of foam you can just plug in a new one (do it quick, of course!)Rebuilding my home in Cypress, CA
Also a CRX fanatic!
I'm not all that computer savvy; my responses are ALWAYS intended for the entire thread, and not meant to single any individual out... The ASTM E-84 test is a test designed to look at the surface burning properties of a material. Samples about 2 ft. wide are used to make the top of a duck, that is perhaps 30 ft. long (if I recall correctly). A very large gas flame is applied to one end of the duct, and drawn into the duct with a large fan. Upon igniting the end of the sample, it is timed to see how long it takes for the flame to reach the far end.
For "benchmarks" to the scale, dry, untreated oak is "100", while asbestos cement board is "0". Anything under "25" is considered to be fire resistant. Every test has its' limitations. Many foams, when tested in this way, immediately fall away from the rest of the sample, to the floor of the duct. Even though this fallen foam burns with great vigor, it is NOT considered in the test- just the spread of the flame across the top of the duct. EVERY foam tested, with the sole exception of urea-formaldehyde (not used since the late '70's), burns with great vigor. This is true whether or not the foam has "fire retardants" added. There is an entirely different set of tests for flame stops, fire blocks, etc. Many of these products are tested, installed as they would be used, in an entire wall assembly. Oddly enough, in these full scale tests it is impossible to distinguish between light steel framing, and typical wood studs. The wood, under these conditions, doesn't "burn" so much as slowly char. The metal, in contrast, quite readily transfers heat through the wall- resulting in a 'hot spot' that can mean failing the test. The short answer to the "wood vs. steel" debate is "no difference in fire rating." ASTM and ANSI are entirely different organizations, with different purposes. I would expect there to be no similarity between their respective standards. Nor is there any reason to expect similarly numbered standards to have anything to do with each other. "E-82" addresses 'spurious disturbances' (whatever those are!) and E-136 has to do with a 'tube furnace.' Your guess is as good as mine! NOW- for grounding. There is nothing wrong with multiple ground rods... but the NEC insists that ALL grounding paths be connected ("bonded") together. The NEC also requires water pipes to be grounded- that is, connected to the grounding system.
It is quite common for water heater elements to fail by leaking current into the water. If the piping were not grounded, it is quite likely that anyone touching the faucet would get shocked. By providing a good ground path to the panel, the current can easily flow- tripping the breaker.
Thanks for the info. I now feel quite comfortable with the foam. I will check with the installation company to see if they have added a fire retardant.
bob
Wool does not give off toxic fumes...it doesn't burn, only chars if you blast #### with flame; that's why they make fire blankets out of it.
Wool carpet, upholstery, etc., is about the safest stuff you can use...
Now I can be really pedantic. On page 37 of Morley's "Structural Insulated Panels" there is a chart from the National Research Council of Canada.The sum of the combustion toxicity for
EPS is 20
PU is 290 (mostly HCN)
Wool is 360 (mostly HCN)
Nylon-6 is 950
Polyacryonitrile is 1200In short, get rid of your nylon and nitrile furnishings and carpets first, then worry about the other stuff.