Im installing a delta 3 phase 1000 amp service and the customer wants a generator disconnect also. Im installing 3- 3inch conduits of 4 #400 parallel (a,b.c,neutral).According to Table 250.122 I should install a 2/0 ground wire.Am I to install this in any one of the conduits? or am I to refer to Table 250.66 and install a 1/0 in each of the conduits? Thanks in advance for advice.
grounding
- Thread starter friday
- Start date
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- Location
- New Jersey
- Occupation
- Journeyman Electrician
Re: grounding
Are your 3 sets of 400's service entrance conductors?
Are your 3 sets of 400's service entrance conductors?
ramdiesel3500
Senior Member
- Location
- Bloomington IN
Re: grounding
I believe you have to install that 2/0 in each of the conduits. I know it sounds like overkill, but thats how we have to do it here! We size the grounding conductor for the entire amperage and then install it in each of the parallel raceways. Someone please correct me if I am wrong!
I believe you have to install that 2/0 in each of the conduits. I know it sounds like overkill, but thats how we have to do it here! We size the grounding conductor for the entire amperage and then install it in each of the parallel raceways. Someone please correct me if I am wrong!
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: grounding
There is that word "ground" and all of its derivative forms getting us in trouble again.
Table 250.66 relates to the Grounding Electrode Conductor. It connects the service to planet Earth. Its size is based on the size of the service conductors. If there are parallel conduits for the service, you only need to put one GEC in one of the conduits.
The way I read this case, the conduits being described are for the service conductors, and they comprise three sets of 400 MCM. That is a total of 1200 MCM. That is above 1100 MCM. So Table 250.66 requires a 3/0 GEC.
Table 250.122 relates to the Equipment Grounding Conductor. It's purpose is to establish a low-impedance path back to the source, so that a fault will cause the breaker to trip on high current. Its size is based on the rating of the overcurrent device. If there are parallel conduits for a feeder, you need to put a full sized EGC in each conduit, per 250.122(F).
Sorry, Ram. But I believe you are wrong.
There is that word "ground" and all of its derivative forms getting us in trouble again.
Table 250.66 relates to the Grounding Electrode Conductor. It connects the service to planet Earth. Its size is based on the size of the service conductors. If there are parallel conduits for the service, you only need to put one GEC in one of the conduits.
The way I read this case, the conduits being described are for the service conductors, and they comprise three sets of 400 MCM. That is a total of 1200 MCM. That is above 1100 MCM. So Table 250.66 requires a 3/0 GEC.
Table 250.122 relates to the Equipment Grounding Conductor. It's purpose is to establish a low-impedance path back to the source, so that a fault will cause the breaker to trip on high current. Its size is based on the rating of the overcurrent device. If there are parallel conduits for a feeder, you need to put a full sized EGC in each conduit, per 250.122(F).
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