NEC table B.310.6

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frenchcomp

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Table B.310.6 applies to underground duct bank with three conductor cable.
Why the smaller cable size is 8 AWG. What's about smaller cables ampacities which may route in underground duct? :confused:
 
Re: NEC table B.310.6

In addition:
I used to route current carrying conductors with cable 3C10AWG or 3C12AWG (small power) so I'd like to know ampacities for these section.
 
Re: NEC table B.310.6

I think you would be safe using 20 amps for the #12 and 30 amps for the #10 (Table 310.16). Just be sure to derate if there are more than 3 current-carrying conductors in the duct.
 
Re: NEC table B.310.6

I don't think anyone would put a single conductor, size #8, into a duct. You generally run them in sets of two or three. That is the difference between the two tables.
 
Re: NEC table B.310.6

OK with 20A for 12AWG and 30A for 10AWG to be safe.
Is it elsewhere clearly stated that for smaller than 8AWG the ampacities will have to follow article XXX or table XXX or be not higher than overcurrent protection?
How can I be sure that NEC permits to route in underground bank duct with this kind of cable size so longer it is not in a table?
What about ambient temp correction factors. May I use also factors from table B.310.6 if I consider 20A-12AWG or 30A-10AWG or does the ambient temp will be non significative for small conductors?
 
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