400 AMP SERVICE METER WITH TWIN 200-AMP MB'S FEEDING TWO SEPARATE ML 200-AMP PANELS. QUESTION IS CORRECT GROUND AND BONDING, i SEE THIS AS THE PANELS BEING SUBS AND REQUIRING #6 EQUIPMENT GROUNDS BONDED TO THE CABINETS AND TWO GROUND RODS WITH 1/0 GROUND WIRE. WELL WATER. PLEASE ADVISE AS I HAVE GOTTEN CONFLICTING ANSWERS.
400-amp residential service
- Thread starter ecimark
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Sierrasparky
Senior Member
- Location
- USA
- Occupation
- Electrician ,contractor
I take it this is a resi 400 amp service.?
You need to bond and ground the main service just like any other main service.
The 200 sub feed are just that. Ground them as usual . If they feed a remote building treat them like seperate service at the remote building - use a ground rod.
You need to bond and ground the main service just like any other main service.
The 200 sub feed are just that. Ground them as usual . If they feed a remote building treat them like seperate service at the remote building - use a ground rod.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
The portion of the wiring between the MB and the MLO panel is a feeder and the EGC would be sized according to 250.122. The service GEC would be sized according to the size of the service entrance conductors which in this case would be the parallel #3/0 and according to 250.66. If you're using only ground rods than the GEC only needs to be a #6.
StreamlineGT
Senior Member
that is how I have mine done, and the AHJ said the EGC was overkill. The rest sounds good though.
ok, it seems as though my line of thinking may have been correct Yea! Correction the service latteral are not paraell, there are two 2" conduits each feeding a 200-amp panel. Im not sure what are utility will supply it with as they dont follow nec. my guess is that they will use 300 at the most.
StreamlineGT
Senior Member
The POCO fed mine with 4/0 Al.
The first part of your statement was accurate, the panels are subs requiring an equipment grounding conductor sized per 250.122
The grounding electrode conductors, sized per 250.66, should originate at the meter or main breakers. Individual runs based on the 200 amp conductors, or single runs based on 400 amp conductors.
(1/0 to water, #6 to rods, #4 to UFER, etc)
The grounding electrode conductors, sized per 250.66, should originate at the meter or main breakers. Individual runs based on the 200 amp conductors, or single runs based on 400 amp conductors.
(1/0 to water, #6 to rods, #4 to UFER, etc)
Cow
Senior Member
- Location
- Eastern Oregon
- Occupation
- Electrician
Are you planning on running 2 feeders to a detached structure? 225.30
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I assume you mean copper. Correct? Also I assume this is a meter/ pnael combo with no service conductors. If that is the case than a 1/0 copper is needed to the water pipes (250.66- Note 2) and #6 to the ground rods. You still need a #6 EGC to the sub panels.(250.122) It does not matter what the utility supplies the service with
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