pparry7@yahoo.com
Member
Can any one help me with which table to use for 200 amp sub feed conductors? Table 310.15(B)(6) or 310.16.
is 4/0 aluminum gould for 200 amp? Thank
is 4/0 aluminum gould for 200 amp? Thank
ampacities
- Thread starter pparry7@yahoo.com
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- Massachusetts
pparry7@yahoo.com said:
You can only use Table 310.15(B)(6) if the conductors are carrying 100% of the load of a dwelling unit.
If it is a sub panel that only carries some of the load of the dwelling unit it has to be Table 310.16.
pparry7@yahoo.com
Member
ampacities
whats the deal with 4/0 ser cable bieng rated at 200 amps? thats what we use for 90% of are sub feeds but I have a job with 2" pvc feeding a 200amp 120/v 240/v sub panel 250 mcm put's over my wire fill.
whats the deal with 4/0 ser cable bieng rated at 200 amps? thats what we use for 90% of are sub feeds but I have a job with 2" pvc feeding a 200amp 120/v 240/v sub panel 250 mcm put's over my wire fill.
pparry7@yahoo.com said:
4/0 SER is not rated for 200 amps, see table 310.16.
It is allowed to be used for a 200 amp 120/240-Volt, 3-Wire, Single-Phase Dwelling Service, but this does not mean it is a 200 amp cable. See the text in 310.15(B)(6) as 480 Sparky mentions.
90% of your sub-feeds are in viloation.
Roger
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- Location
- Massachusetts
pparry7@yahoo.com said:
3/0 Copper will fit great.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
roger said:
#4/0 Al is rated for 180 amps. Those sub feeds would be a violation if the connected load was greater than 180 amps and protected at 200 amps. However #4/0 Al can be used to feed a subpanel if the connected load is 180 amps or less. This is due to the fact that 180 amps is not a standard size listed in 240.6 so the next standard size (200 amps) maybe used. This is under the 2005 NEC.
tryinghard
Senior Member
- Location
- California
Looks to me like 4/0 SER al is rated at 150A, see 338-10 & 334-80. I think this could be a problem if one uses a "farm" type 200A residential panel, it has feed thru lugs and about 8 space distribution, it would be easy to just run 4/0 SER to a sub panel but this sounds like a violation if the farm panel is mounted on the house.
I guess 300 SER al or 4/0 cu are the only choices for 200A rated SER feeder, and that's not even considering attic temperature correction factors - these could easily be 58% (114-122?) with SER al, am I looking at this right :-?
I guess 300 SER al or 4/0 cu are the only choices for 200A rated SER feeder, and that's not even considering attic temperature correction factors - these could easily be 58% (114-122?) with SER al, am I looking at this right :-?
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
tryinghard said:
As of 2008 ser must be use at 60C if it is used for interior wiring. 2005 still allows 90C
tryinghard
Senior Member
- Location
- California
Dennis Alwon said:
Are you sure that's not the way I understood 338-10 & 334-80, so my post included 60 degree column
tryinghard
Senior Member
- Location
- California
infinity said:
Trevor,
How does this line up with 240-4(B)? If I have a calculated load at 195A I understand I can use a 200A OCPD with the 4/0 Al at 75?
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
tryinghard said:
2005 NEC art. 338.10 says excluding 334.80 however the 2008 omits the words "excluding 334.80"
tryinghard
Senior Member
- Location
- California
Dennis Alwon said:
Including/Excluding...What-ever :grin:
I see it now.
2008
2008
I'm curious. Any of you guys with the 2008 ROPs and ROC's...
when the decision was made to place the 60 deg.limitation on SE cables, was there any discussion on 310.15(B) 6 ??
I know its the same cable as always. but now we have the guru's saying 4/0 al is a 150 amp cable vs a 180 amp cable, but it's still good as 200 amp "house" service cable. Strange
2008
I'm curious. Any of you guys with the 2008 ROPs and ROC's...
when the decision was made to place the 60 deg.limitation on SE cables, was there any discussion on 310.15(B) 6 ??
I know its the same cable as always. but now we have the guru's saying 4/0 al is a 150 amp cable vs a 180 amp cable, but it's still good as 200 amp "house" service cable. Strange
- Location
- New Jersey
- Occupation
- Journeyman Electrician
tryinghard said:
It's simple your calculated load cannot exceed the ampacity of the conductor. Under the 2005 SE cable can be used at 75 degrees C which would make it's ampacity 180 amps. You cannot protect this at 200 amps if the calculated load is 195 amps. You will need a larger conductor.
tryinghard
Senior Member
- Location
- California
infinity said:
Well 240-4(B) allows me to.
- Location
- Massachusetts
tryinghard said:
No, read what Rob said, 240.4(B) allows you to use a 200 amp breaker, it does not allow you load the cable past it's rated ampacity.
tryinghard said:
Absolutely not, that 310.16 will limit the the amount of load you are legally allowed to place on that cable to 180 amps and that is regardless of the fact you can use a 200 amp breaker with it.
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tryinghard
Senior Member
- Location
- California
iwire said:
&
infinity said:
Wow, I was just focusing on the breaker while screaming about the load. Of course I cannot over load the conductor! :roll: Thanks guy's
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