Sizing Residential single phase 400amp parallel service feeder

Status
Not open for further replies.

cpinetree

Senior Member
Location
SW Florida
Please help me verify I am correct in sizing the feeder to this service.

2 pipes from the meter can to a 1-400amp single phase breaker 75degree terminations.
Each pipe (underground) contains:
2-4/0 Alum XHHW-2
1-2/0 Alum XHHW-2

The home load calcs to 310amps.

The 400amp breaker then feeds 2-200amp main breaker panels (within 5 foot of the 400amp breaker)
from the 400amp breaker each panel is fed with
2-250mcm Alum XHHW-2
1-3/0 Alum XHHW-2
1-#6 Copper THHN2

Is this correct?
I can go to the next standard size breaker (400amp) even though the parallel feed is only good for 360amps correct?
 

mwm1752

Senior Member
Location
Aspen, Colo
Please help me verify I am correct in sizing the feeder to this service.


The home load calcs to 310amps.

Is this correct?
I can go to the next standard size breaker (400amp) even though the parallel feed is only good for 360amps correct?

Service lateral conductors shall carry the load, be within 83% of breaker
 

Smart $

Esteemed Member
Location
Ohio
Service lateral conductors shall carry the load, be within 83% of breaker
Florida is still using the 2008 NEC, thus Table 310.15(B)(6). Paralleled ratings are not specifically permitted, but was confirmed at some point by CMP comment to a proposal, IIRC.
 

cpinetree

Senior Member
Location
SW Florida
Florida is still using the 2008 NEC, thus Table 310.15(B)(6). Paralleled ratings are not specifically permitted, but was confirmed at some point by CMP comment to a proposal, IIRC.

Yes we are on 2008, I should have stated that, Thank you!

And thanks for the CMP info.
 

cpinetree

Senior Member
Location
SW Florida
After reading the CMP info, I don't think it would apply to this situation as I am terminating in a single 400 amp breaker (not 2 - 200amp breakers).

Please correct me if I am wrong.

So I think the question remains, can I up size the main breaker to a 400 amp on the service lateral, when the paralleled wire rating is 360 amp?



edit: spelling
 

Smart $

Esteemed Member
Location
Ohio
After reading the CMP info, I don't think it would apply to this situation as I am terminating in a single 400 amp breaker (not 2 - 200amp breakers).

Please correct me if I am wrong.

So I think the question remains, can I up size the main breaker to a 400 amp on the service lateral, when the paralleled wire rating is 360 amp?



edit: spelling
The proposal/CMP-comment may have been for 2011 (perhaps even 2014... IDK), but there was no change in 2011 compared to 2008, other the move to 310.15(B)(7).

Regardless, you are permitted to upsize the main OCPD rating to next standard size per 230.90(A) Exception No. 2.
 

cpinetree

Senior Member
Location
SW Florida
The proposal/CMP-comment may have been for 2011 (perhaps even 2014... IDK), but there was no change in 2011 compared to 2008, other the move to 310.15(B)(7).

Regardless, you are permitted to upsize the main OCPD rating to next standard size per 230.90(A) Exception No. 2.

Perfect!!
Thank you for the confirmation.
 

Canton

Senior Member
Location
Virginia
Occupation
Electrician
Please help me verify I am correct in sizing the feeder to this service.

2 pipes from the meter can to a 1-400amp single phase breaker 75degree terminations.
Each pipe (underground) contains:
2-4/0 Alum XHHW-2
1-2/0 Alum XHHW-2

The home load calcs to 310amps.

The 400amp breaker then feeds 2-200amp main breaker panels (within 5 foot of the 400amp breaker)
from the 400amp breaker each panel is fed with
2-250mcm Alum XHHW-2
1-3/0 Alum XHHW-2
1-#6 Copper THHN2

Is this correct?
I can go to the next standard size breaker (400amp) even though the parallel feed is only good for 360amps correct?

Are your feeders off your 400 amp breaker TAPs?
If so your EGC's to your 200 amp panels should be #3 copper or #1 aluminium .
 
Status
Not open for further replies.
Top