Fire hazard!

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electricaldoc

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Does any one understand how this works or how to explain what causes it? If you plug too many devices into extension cords and into one receptacle. I know it is true that it causes fires, but from NEC regulation not a violation. From an electrical point of view as long as ampacity of wire for extension cord is higher than breaker. Then breaker should trip befor cord will burn, and there should not be enough of voltage drop to cause any problems. So exactly how does it cause a fire, and how would I tell how many is too much?


Thanks any help appreciated.

[ March 04, 2005, 07:20 PM: Message edited by: electricaldoc ]
 
Re: Fire hazard!

How long do you think a 20 amp circuit breaker will take to trip with the following loads=
20 amperes
25 amperes
40 amperes
 
Re: Fire hazard!

many years ago ---berger king was just starting out. we had just finished(one week) the construction of a two story office building for their executives! the cleaning crew plugged a vaccuum cleaner into the circuit feeding the coffee pot. the vaccuum had a bad cord on it and tripped the 20 amp circuit breaker. since they had no access to the electrical room, and wanted coffee, the cleaners installed a 15 amp zip cord to power up the coffee pot. they forgot to turn the pots off at the end of the night. the building burnt to the ground four hours later!! the 15 amp extention cord started the carpet on fire!
 
Re: Fire hazard!

Flexible cords and cables can be as small as #18. See table 400.4 and 400.12. That allows a 18 Ga. extension cord to be plugged into a 20A circuit wired with #12.

If you look at the allowable ampacity in table 400.5, #18 is only good for 7-10 amps. Good enough for your table top lamp, but not anything big.

Steve
 
Re: Fire hazard!

And watch out for those "Made in China" cords as many are even smaller and will not trip a 20 amp breaker. One reason I don't like 20 amp circuits for general purpose receptacles! But thats just me.
I think we will see a trend with UL requiring fuses in the plugs of these small extension cord that will limit the load like the christmas cords have gone. this will go along way in preventing many fires. a few of the cords I have on the truck have a 10 amp breaker built into the plug. and it works. Can't use more that one drill or saw on them at a time. the cord is 16awg.
 
Re: Fire hazard!

Since the cords have been removed from Article 240, I agree with you Wayne. Even without overcurrent protection in the cord cap, you may see a cord listed for use with 15 and 20 ampere circuits that have smaller conductors and improved insulation. :D
 
Re: Fire hazard!

I don't get it, if CMP10 didn't feel it was their responsibility to evaluate flexible cord and tinsel cord use, then why do they still feel qualified to evaluate fixture wire?

I know this all stems from afci requirements and all the home fires due to appliance cords, but this change just seems inconsistant. They should have made the same change in section 240.5(B)(2).
 
Re: Fire hazard!

Bryan, does an extent ion cord become part of the permanent building wiring or does an appliance cord? How about fixture wire? It is the contention of CMP-10 that the Code doesn't generally jump out of the wall and cover things that are not part of the building wiring system. :D
 
Re: Fire hazard!

Thanks Charlie, that seems reasonable to me. I still don't know why someone would need 100' of 16 AWG tapped from a 20-ampere branch circuit?
 
Re: Fire hazard!

Years ago I once saw an apartment in a building built in 1902 originally gas lit retro with bx for lighting a few receptacles were added from sconce lights that were splice and soldered and taped and plastered over ;)
 
Re: Fire hazard!

Telcoutlet.jpg
 
Re: Fire hazard!

What i don't understand is in residential we have a wall space requirment to stop the use of exstention cords,but there is no such rule in commercial.What makes them think a cord wont be used to go to whatever they may need ?
 
Re: Fire hazard!

Originally posted by jimwalker:
What i don't understand is in residential we have a wall space requirement to stop the use of exstention cords,but there is no such rule in commercial.What makes them think a cord wont be used to go to whatever they may need ?
Click to expand...
It would be wasteful to require commercial spaces to have an outlet every 12'. :roll:
 
Re: Fire hazard!

Some people. I can't beleive that receptacle isn't grounded.

Edit: And is the red one hot?

[ March 08, 2005, 04:39 PM: Message edited by: physis ]
 
Re: Fire hazard!

yes and that red wire should have white tape.
Bob i don't agree,Often we have wasted outlets in residential.Are you saying that a cord is safe if used in commercial ? They will do the same thing as people did in the 20's when the spacing wasnt a code.They want the copy machine over on this wall but there is no outlet.Solution #1 call electrician ,cost $200 ,solution #2 go to big orange,cost $10
 
Re: Fire hazard!

Originally posted by jimwalker:
They will do the same thing as people did in the 20's when the spacing wasnt a code.They want the copy machine over on this wall but there is no outlet.Solution #1 call electrician ,cost $200 ,solution #2 go to big orange,cost $10 [/QB]
Click to expand...
Jim, how would you ever write a code requirement for receptacles in commercial and industrial occupancies? It would be as large as the NEC itself to cover every possible sitation.

Do we really need an outlet every 12 feet inside of a warehouse? :roll:
 
Re: Fire hazard!

Sam,

I didn't really check that! Boy, it's hard to find a good electrician. :D

The homeowner wanted the window AC to work 'cause her son was coming home from college. When I showed her the burned open in the splice in the photo (sorry that its hard to see) she was amazed there was a problem. "It worked fine for years."
 
Re: Fire hazard!

Yeah, I wouldn't figure that to be used for a lamp or a clock, it would have to be for something industrial wouldn't it. :D
 
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