Bus Bar Ampacity

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iwire

iwire

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I seem to recall that somewhere in the NEC the ampacity of bus bars are discussed.

I can not find it now.

Am I nuts or am I just having trouble finding it. (OK it could be both ;))

Anyone?
 
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iwire said:
I seem to recall that somewhere in the NEC the ampacity of bus bars are discussed.

I can not find it now.

Am I nuts or am I just having trouble finding it. (OK it could be both ;))

Anyone?
Click to expand...

Bob anytime you cant find something it's not likely it's in there LOL
We all are a bit nuts or we wouldnt be here.
 
This one?

366.23 Ampacity of Conductors.

(A) Sheet Metal Auxiliary Gutters. Where the number of current-carrying conductors contained in the sheet metal auxiliary gutter is 30 or less, the correction factors specified in 310.15(B)(2)(a) shall not apply. The current carried continuously in bare copper bars in sheet metal auxiliary gutters shall not exceed 1.55 amperes/mm2 (1000 amperes/in.2) of cross section of the conductor. For aluminum bars, the current carried continuously shall not exceed 1.09 amperes/mm2 (700 amperes/in.2) of cross section of the conductor.
 
Bob

This has nothing to do with your question, but is somewhat related. I was recently given the following information from a Burndy rep.

A copper grounding strap measures 0.75" by 0.040" This converts to 38,240 circular mills, which is just less than a 4 AWG conductor.

Brian
 
366.23 Ampacity of Conductors

(A)Sheet Metal Auxiliary Gutters.


Copper 1000 A per square inch

Aluminum 700A per square inch
 
I thought it was a dumb place for it (only knew about because it had been a "trick" question on a test). Perhaps I should submit a proposal in/for the 2008 NEC? Switchboards and panelboards, seems so much more appropriate for busbar.
 
Rockyd said:
I thought it was a dumb place for it (only knew about because it had been a "trick" question on a test). Perhaps I should submit a proposal in/for the 2008 NEC? Switchboards and panelboards, seems so much more appropriate for busbar.
Click to expand...

The bus bars in panelboards and switchboards are sized based on heat rise tests not based on current density. Do not try to mimic their sizing.
 
Rockyd said:
I thought it was a dumb place for it (only knew about because it had been a "trick" question on a test). Perhaps I should submit a proposal in/for the 2008 NEC? Switchboards and panelboards, seems so much more appropriate for busbar.
Click to expand...


Sorry to say, but proposals for the 2008 ship has sailed. You could try for the 2011.
 
Bus Bar Ampacity

One of the best sources today is Copper Development Association as indicated by one of the responders above at:

www.copper.org

Get their publication No. 22. It has minimal cost in hard copy but is free electronically. It will tell you all you need to know about sizing bus bars and compensating for your ambient temperatures and temperature rises.
 
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