wire size
- Thread starter tdjs
- Start date
- Status
- Location
- Massachusetts
Re: wire size
I might go with two sets of 350 Kcmil copper in two 3" RMCs.
One set of 1500 Kcmil copper in 5" RMC would do it.
I might go with two sets of 350 Kcmil copper in two 3" RMCs.
- Location
- Illinois
- Occupation
- retired electrician
Re: wire size
6 XHHW-2 400kcmil in one 3"
6 XHHW-2 400kcmil in one 3"
- Location
- Massachusetts
Re: wire size
[ September 24, 2005, 01:29 PM: Message edited by: iwire ]
You must be talking about EMT?
[ September 24, 2005, 01:29 PM: Message edited by: iwire ]
tx2step
Senior Member
- Location
- North Texas, DFW area
Re: wire size
If you could use EMT, you could get by with 3". Per Table C.1, you can put 6 #400 XHHW-2 (or 6 #400 THHN) into 3" EMT.
Question: Why did you choose XHHW-2 over THHN? Both are rated 380A at 90 degrees.
You would have to derate either to 80% = 380X.80= 304A/wire, right?
Edited to add: Bob beat me to it while I was typing my reply and raiding the fridge!
[ September 24, 2005, 01:39 PM: Message edited by: tx2step ]
Don, for an OH service, wouldn't you probably use RMC? Per Table C.8, the max. # in 3" is 5 conductors for XHHW-2. You would need 3-1/2" if you used RMC. Same deal if you use IMC.
If you could use EMT, you could get by with 3". Per Table C.1, you can put 6 #400 XHHW-2 (or 6 #400 THHN) into 3" EMT.
Question: Why did you choose XHHW-2 over THHN? Both are rated 380A at 90 degrees.
You would have to derate either to 80% = 380X.80= 304A/wire, right?
Edited to add: Bob beat me to it while I was typing my reply and raiding the fridge!
[ September 24, 2005, 01:39 PM: Message edited by: tx2step ]
tx2step
Senior Member
- Location
- North Texas, DFW area
Re: wire size
For a dwelling, could you use 2 sets of #250 Cu THHN, each set in 2" RMC?
Bob, IF this was for a dwelling service entrance, could you use Table 310-15(B)(6) wire ratings? Are you prohibited from using these ratings if you parallel the conductors?
For a dwelling, could you use 2 sets of #250 Cu THHN, each set in 2" RMC?
- Location
- Massachusetts
Re: wire size
2step in my opinion Table 310.15(B)(6) can not be used to parallel conductors.
That table is not an ampacity chart, part of the text that goes with it says "For dwelling units, conductors, as listed in Table 310.15(B)(6), shall be permitted as".
I take 'as listed' to mean we can only use that table if we follow the table exactly.
2step in my opinion Table 310.15(B)(6) can not be used to parallel conductors.
That table is not an ampacity chart, part of the text that goes with it says "For dwelling units, conductors, as listed in Table 310.15(B)(6), shall be permitted as".
I take 'as listed' to mean we can only use that table if we follow the table exactly.
- Status