service conductor size

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c_picard

Senior Member
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Hey folks,
Just a quick (HA!) question on service entrance conductors.
I need to change out a main breaker enclosure(200A), the existing 200a main lug panel
will remain. It is an older CH, main lugs only rated for 40degC.
The existing conductors are 4/0 copper.
I was thiunking that they should be upsized because of the terminal rating, is that correct?
This is not a dwelling.

Thanks
Charles
 
c_picard said:
Hey folks,
Just a quick (HA!) question on service entrance conductors.
I need to change out a main breaker enclosure(200A), the existing 200a main lug panel
will remain. It is an older CH, main lugs only rated for 40degC.
The existing conductors are 4/0 copper.
I was thiunking that they should be upsized because of the terminal rating, is that correct?
This is not a dwelling.

Thanks
Charles
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I don't know anywhere in the code that it would require you to use 40C for termination.

What is the insulation on your wire. You may have to use 60C and that is probably why they used 4/0 copper. If it were 75C then 3/0 copper would have sufficed.
 
It is an older (40yrs) service, I always thought that conductor ampacity couldn't exceed the terminal ratings(don't have my codebook handy).
I know the table doesnt go below 60c, but even at 60c 4/0 copper is only good for 195A?
 
Oh,
and conductor insulation/ampacity is only used in respect to derating, no? The result of derating calcs still can't exceed termination ratings?
 
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