Conductor sizing for conduit fill

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Jay Q

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We are doing a job that requires a 3ph 225amp feeder for a panel.
The wire size for that ampacity is 4-#4/0 and 1-#4g. in 2 1/2" conduit.
The building has exisiting empty 2" conduit run to the spaces.
I calculated the wire size using the tables in chapter 9 and i see that i can not use that wire in a 2".
I think if we us a bare #4 ground i could use the existing 2" conduit.
Thats using 4 - #4/0thhn and a bare #4.
My question is do i use chapter 9 table 8 to size the bare #4 in Overall/Area/in.? colume?
 
Jay Q said:
We are doing a job that requires a 3ph 225amp feeder for a panel.
The wire size for that ampacity is 4-#4/0 and 1-#4g. in 2 1/2" conduit.
The building has exisiting empty 2" conduit run to the spaces.
I calculated the wire size using the tables in chapter 9 and i see that i can not use that wire in a 2".
I think if we us a bare #4 ground i could use the existing 2" conduit.
Thats using 4 - #4/0thhn and a bare #4.
My question is do i use chapter 9 table 8 to size the bare #4 in Overall/Area/in.? colume?
Click to expand...

830.179 Table 1 Note(3) Equipment grounding or bonding conductors, where installed, shall be included when calculating conduit or tubing fill. The actual dimensions of the equipment grounding or bonding conductor (insulated or bare) shall be used in the calculation."

FROM NECH "All insulated, covered, and bare conductors occupy space within a raceway. Therefore, all installed conductors must be included in the raceway fill calculation, including non?current-carrying conductors such as equipment grounding conductors, bonding conductors, and bonding jumpers. The only exception to this rule is the addition of an uninsulated grounding conductor permitted in trade size 3/8 flexible metal conduit (see the footnote to Table 348.22). The dimensions of bare conductors are given in Table 8. "
 
Is the 2" a metal conduit that can qualify as an equipment ground in accordance with 250.118?

If not then I would say for a bare #4 you would use the area given in Table 8 Chapter 9.

Chris
 
raider1 said:
Is the 2" a metal conduit that can qualify as an equipment ground in accordance with 250.118?

If not then I would say for a bare #4 you would use the area given in Table 8 Chapter 9.

Chris
Click to expand...

And, of course, that is an excellent point. Metal conduit then there is no need for another EGC unless specs call for it.
 
Dennis Alwon said:
And, of course, that is an excellent point. Metal conduit then there is no need for another EGC unless specs call for it.
Click to expand...

I typically always pull an EGC of the wire type with my feeders but in a circumstance such as this I would definatly look at using the conduit as the EGC unless, like you said ,the specs require a wire run for the EGC.

Chris
 
You might want to look into using compact conductors...4/0 cu. thhn = .2780 x 4 = 1.112 + # 4 awg cu. = .0730. Total = 1.1850.(2" = 1.342)

Rick
 
Dennis Alwon said:
I do plumbing without a permit, carpentry without insurance and electrical without a license...But you'll love my rates- Rhymes with Orange
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Copy cat! :mad: (;))
 
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