Parallel Equipment grounding conductor size

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Re: Parallel Equipment grounding conductor size

well tramike, it seems that no one else has anything to add...and we are left with an incomplete answer.
 
Re: Parallel Equipment grounding conductor size

I agree, does not seema s though anyone can give a concrete answere to what the code actualy requires
 
Re: Parallel Equipment grounding conductor size

as you get to larger size conductors it also has to do with heat. The heat is equal to the square of the current. You raise the current by 2 times and the heat quadruples :eek:

Pierre
 
Re: Parallel Equipment grounding conductor size

250.122(F)(2) only applies to multi-conductor cable. Don mentioned 250.122 (A), but that is a general requirement and 250.122(F) is a specific requirement, and thus takes precedence. 250.122(F)(1) makes no mention of limiting the EGC to the size of the ungrounded conductors in the raceway. I would have to say 250 KCM EGCs are required.
 
Re: Parallel Equipment grounding conductor size

Originally posted by eprice:
......I would have to say 250 KCM EGCs are required.
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I couldn't agree more!
250.122(A)General.....is exactly just that........general. The note at the bottom of Table 250.122 states "Where necessary to comply with 250.4(A)(5).........shall be sized larger", is to take into account Effective Ground-Fault Current Path.
 
Re: Parallel Equipment grounding conductor size

I also agree with the 250kcm.

This was answered correctly with the first response from dereckbc, an hour and fifteen minutes after it was asked. I really thought everyone understood that was the answer.
 
Re: Parallel Equipment grounding conductor size

I am still baffled by this.

Originally posted by eonebrandon:
did you run it thru a estimating program yet? if you run 100' both ways you save at least $2,500 and if the run is longer, start multiplying....$$$$
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Please break down how 10 runs is cheaper than 5 runs for a 100 feet of length.

Run 10 conduits instead of 5.

Set up the pull 10 times instead of 5.

80 terminations instead of 40.

Buy 1000' 2" instead of 500' of 3.5"

Buy 4000' 3/0 instead of 2000' of 600.

I just do not see how I would come out $2500 ahead. :confused:

Did your estimating program include labor?

EDIT: 500 to 600

[ March 02, 2004, 10:07 PM: Message edited by: iwire ]
 
Re: Parallel Equipment grounding conductor size

Bob, I wondered the same thing. Are we getting so lazy and machine dependent, that simple math associated with tasks or material purchases can not be imagined or actually figured in the mind anymore?

I'm no genius, (surprise :D ) but I saw the point you made early in this thread, even with not using a "program". ;)

I still wonder why calculators are allowed in some elementary class rooms.

I pride myself in doing a lot of math off the top of my head, and then I see young people that can't make change if the cash register is down. :roll:

Roger
 
Re: Parallel Equipment grounding conductor size

Exactly! :D :D :D

Roger
 
Re: Parallel Equipment grounding conductor size

Here I go making assumptions, but isnt that amoung other reason why you loose so many amps the larger your conductor becomes?
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Well this quote and "skin effect" still baffles me. Skin effect only becomes appearant in high frequencies above 10Khz. And who changed Ohm's law? Bush administration? :D
 
Re: Parallel Equipment grounding conductor size

by Pierre: The heat is equal to the square of the current. You raise the current by 2 times and the heat quadruples as you get to larger size conductors it also has to do with heat
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I understand and agree with you.

In an example: 500kcmil does not have twice the ampacity of 250kcmil, even though the area is doubled. Can I assume then, the reason for the ampacity "discrepency" lies in the fact the surface area of the 500 is not quadruple that of 250. Since this is so, it cannot dissipate the heat in proportion?
 
Re: Parallel Equipment grounding conductor size

What about history? Check the NEC as reciently as 96 and find the requirement to not to have to exceed the ungrounded conductor (UNGC) size listed specifically under paralleling...do you still think it is just a general rule? Why would you ever need to exceed the UNGC size? You would only need to protect against what the UNGC conductor could deliver. I am at a lost as to how to reply to the "doing it in my head" line of thought...while I certainly recognize that the ability is necessary, does your "head" have the ability to instantly and daily update the latest commodities (like copper for example) and integrate this info into your bid...I can guarantee that your competion does. That sounds like the words of a person that "don't need no puter, I've gotten by this far without knowing how to do Winders" he he? just kidding but come on...
 
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