Okay – I’ve got a nice weatherproof box with twin duplex receptacles at the end of my pricey 100′ 10-gauge main prop cord. Nice to be on one cord if I’m working in a client’s yard, like now.
Compressor goes into one receptacle, couple extension cords in the others, maybe the battery charger in the last receptacle.
Being that I’m outside, it’s usually plugged into a GFI recep. on the house
IF I’m using the chop saw, and the compressor kicks on, like as not the 20A breaker in the house will trip, if not the GFI, which will eventually die, even if it’s a 20A-rated one, and with nothing else on the load side.
SO –
What if there was a little heavy-duty solid-state circuit in my weatherproof box, such that if I was pulling 8-10 amps on outlet #1 (using the chop saw, circ saw, or the compressor), it would cut off outlets #2 and #3 for the duration of the load, while leaving outlet #4 on (the radio/charger one).
This means – if the compressor is on, I would have to wait before using either saw – not a big deal; I do that anyway.
BUT – if I’m sawing, the compressor won’t try to kick on until I’m finished.
Any value in this, y’all think?
Forrest – thinking; too full of Chinese buffet to move
Replies
well as long as nobody is using a nail gun and the comp has no leaks, then it should be fine. I don't fully understand the question though
There's enough youth in this world, how 'bout a fountain of SMART??!!
I don't fully understand the question though
He's asking about some sort of in-use, load sensing switch. That way, if he's running the chop saw or the like, and the compressor kicks on, that the swithc would be "smart enough" to not let the compressor kick on a pull enough load to knock all of the power off at the working end of this extension cord. (Also not randomly triping the client's CB, which Murphy will have wired to the VCR or a fridge or the hard-to-program MW). ¿Mas Claro?Occupational hazard of my occupation not being around (sorry Bubba)
oh, thanks
Forrest: I have no clue
There's enough youth in this world, how 'bout a fountain of SMART??!!
"well as long as nobody is using a nail gun and the comp has no leaks, then it should be fine. I don't fully understand the question though"
Suggest you not make the judgements like "it should be fine" if you do not have a clue. (:-)
well, I knew there would be plenty of other answers to contradict mine
There's enough youth in this world, how 'bout a fountain of SMART??!!
I've got some GFI 4 ways that do basically the same thing. They'll flip if overloaded instead of flipping the house breaker. So I just have to flip them back as soon as I'm done cutting or compressing instead of having to go to the breaker box.
http://grantlogan.net/
But you all knew that. I detailed it extensively in my blog.
If that was available I would buy it in a second. It happens to me all the time, when I turn off the table saw or chop box , the compessor has tried to kick on and is now just humming, which requires turning it off then back on again. Not a big deal just a PITA.
Probably if I used better cords then the breaker would trip instead.
Good thought, but I'd be concerned somehow a table saw would get pluged into the interrupted outlet and present a hazard, or a router, or a grinder.....
R
How about this, have a booster type device, like floor finishers sometimes use, to eliminate the problem. It must be a capacitor.
Like a transfer switch from a gen-set? senses power from POCO or Gen and won't allow both, but in reverse?
Spheramid Enterprises Architectural Woodworks
"Welcome to Poo-ville, can I have your socks?
Seriously Folks, I need a home for 3 lovers of your life.
Yeah - sorta' kinda'
Forrest
It's kinda-sorta.
Joe H
Thanks - I always get good input here!
;-)
Forrest
There are various types of load monitors for a house, some electric companies use an electric meter that monitors the KW demand in a 15 minute period if you have a high peak demand they charge you more as recorded by the meter.
A load monitor has a coil around the incoming hot legs, this sences and displays the demand, some of the more sophisticated monitors can be set up to give priority to one circuit and give different levels of priority to other circuits. If the compressor was on the first circuit to shut down then it wouldn't start until the load was back to a level that would accomidate it.
This all sounds like what you want except for the price,and the size of the box for the relays.
Dencor was one of the makers, in the 80's they were a 5 to 600 dollar item.
Hmmmmm.
I'm thinking.
Forrest
My thought was basically the same as SeeYou's.
Why don't you just put GFI's in that fancy little box you have, instead of the standard receps ?
Life doesn't often leave a very easy trail to follow.
Well, then I still have to walk back to my fancy box, and who's to say my GFI will trip before the one on the client's outside wall?
Forrest
I did some weekend work at an office buiding and just a few hours into the job had to pack it in because I tripped a breaker. The breaker was locked up in a second floor office and, of course, there was no access.
Solved that problem by installing a 15A breaker in the back of my van and feeding a quad. My breaker trips first if there's an overload. Just a minor inconvenience instead of having to shut down the job.
Most of the time the power demand alternates between the compressor and the other tools so it's no big deal.
Automatic load sensing switches are normally used to turn on other loads but I don't see why a circuit couldn't be built where the slave relay would do the opposite and disconnect.
"Well, then I still have to walk back to my fancy box, and who's to say my GFI will trip before the one on the client's outside wall?"
Or fed through their back window to an outlet in their basement, and they don't get home from work 'till 5 pm, and they didn't give you a key...
You make some, I'll buy one.
What about remote reset on the GFCIs?
Only half joking, crazier things are sold everyday! I put a CD player in DW's car that has a remote....uhhhh, do we really need a remote for something we're sitting right next to?
And to think I used to have to get off the couch to change the TV channel...such hardship!
Everything will be okay in the end. If it's not okay, it's not the end.
I've been in car stereo "dB Drag Racing" contests. You have to have a remote, because their insurance carriers won't let them hold a contest where the participant is in the car, just the calibrated microphone.
Best in the Volvo was 142 dB. Official and printed on the chart; but kind of middle of the road as those things go.
Actually, too much time in a car at that level makes you nauseated, from the internal organs wiggling around.
Yeah, that's a practical hobby!
Forrest
Hmmm, can't say I thought of that! I'm thinking that 140 db would give the little truck a hemorage or something ;-)
There are similar mangement systems in motorhomes, keeps from kicking park breakers when demand is more than supply. They've got a pre-programmed priorty for taking things offline to stay under given setting.
I like your idea...Might have a real place on jobsites if it could be done fairly cheap.
Everything will be okay in the end. If it's not okay, it's not the end.
Yes exactly. If you're luck you can climb into the basement through a window. Been there done that.I thinks its a very good idea.
Buy another extension cord?
His issue is not the gfci function, just overload and popping the house circuit breaker. A problem sometimes if HO is not there. Even bigger problem if some critical item shares that dead circuit (like the freezer full of meat).
One was would be for him to have a secondary breaker in a box that was lesser rated, IE 15 amp. At least then he can reset outside.
Current sensing relay.
http://www.tempco.com/Instrumentation/current_sensing_relay.htm
The only problem is that NC contact is limited to 1/4 hp.
So you would need to have it operate another relay.
Here is another one.
http://www.grainger.com/Grainger/items/1EJF6
It appearss to have 15 amp contacts and could directly operate the other receptacles.
But I would want to see the catalog specs.
Looks like it is a Magnacraft so you should be able to find the catalog pages.
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Boeing calls it Load Shedding. Google showed quite a few interesting hits when I used the criteria of Load Shed 110v.
Load shedding is like a priority system. Higher ranking loads stayed on-line while others were temp interrupted during the peak or reduction of sources (like a failed gen).
Edit to add: most of the links the searchsuplied were for computer related but there was 1 or 2 from patents online that I think were relevant.
Edited 4/8/2008 8:04 am ET by john7g
You could possibly use the current sensors sold for shop vacuum systems. Plus a honkin' contactor relay.
Yes, put me on your mailing list!
Two thoughts:
1) For what you describe, I think it would be sufficient to have this thing plug in-line, like a Y/T-splitter. Input from the wall, one always-on, one cut-off. I'll split each how I want to - the way I tend to get distracted it might be good for me to put the radio on the cut-off circuit. :)
2) Even better would be if you could sense the line conditions on the circuit passively, so I could just plug the widget into the compressor directly. This way, I can use it in the shop too, if the saw is on the same circuit, and I'm using the wall outlets. This potentially doubles your market. I'm pretty sure this is doable, but I decided early on to bail on EE. I know an EE who does power supply design who I could put you in touch with if you want to go this way.
Edited 4/8/2008 3:33 pm ET by bill_mcgonigle
Edited 4/8/2008 3:34 pm ET by bill_mcgonigle
it is a simple yet great idea, a load sensing multiple outlet extension cord that will not let you draw more load than the breaker will allow thereby eliminating all need whatsoever to reset the breaker. absolute genius.
if you can do it for a reasonable cost you may be on to something.
however it may be still better yet to utilize additional cords and breakers to power up the stuff you need so that no breakers are overloaded, thereby eliminating all need whatsoever to reset the breaker.
the good news is you can get all that into one supply cord for less than the cost of a roll of duct tape (hint hint)
http://www.autoctrls.com/acatalog/Split_Core_AC_Current_Switches.html
You'd still need a relay to carry the load of the compressor.
it's probably cheaper to buy a generator!
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
Once, when I had a compressor on a extension cord like that, and the compressor would trip the breaker on starting, I figured out to drag my honkin' drill press out to sit by the compressor, plug it in too, and leave it running. The free-running drill press, on "detecting" a dip in line voltage, would act like a generator and provide the half-second or so of extra current needed to get the compressor started.
It worked! (And before anyone argues with me, remember I AM an electrical engineer, and I studied motors, generators, and power transmission in college.)