Little help

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Oakey

Oakey

Senior Member
Location
New Jersey
I am helping a fellow elec cont and we are pulling #250 copper for a 50 kw generator. What size ground am I required to use for this application for these conductors? What section of the code would relate to this question pls. Thanks guys
 
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Look at Table 250.122 for the equipment ground conductor size.
It is based on the size of the overcurrent protective device.
Grounding electrode conductor is from 250.66 based on the ungrounded conductors.
 
Thx guys..Sryy to be a little vague before, I was running out the door earlier :smile:. It is 240 v 200 amp and we'll check out the tables as suggested , just rusty on this.
 
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Must be 50kVA then? (208 FLA at 240V/1phase)

The reason I asked, is that you need to also upsize the ground if you are upsizing for voltage drop...

Sure you only want 200A OCP?
 
Although allowed by code to use metallic conduit as the EGC, performance-wise it is best to use an insulated conductor...or even better yet, use the metallic conduit supplemented by an insulated conductor. Just in case Money is no object.:wink:
 
I'm going to join Oakey and ask that we discuss this a little so that I might clear my head.
If we have a generator that is not an SDS we are not supposed to connect our grounded and grounding conductors so we don't bond the grounded at the generator. Our generator grounded eventually bonds to our equipmnt grounds thru our service panel connection.
With that in mind, is there any need to pull and equipment ground to the generator larger than the eq. ground needed for charger/control circuit/heater "house" circuits to ground the frame/housing ?
 
augie47 said:
With that in mind, is there any need to pull and equipment ground to the generator larger than the eq. ground needed for charger/control circuit/heater "house" circuits to ground the frame/housing ?
Click to expand...
Gus, are you suggesting we treat a generator as a source and not a load??? :wink:
 
LarryFine said:
Gus, are you suggesting we treat a generator as a source and not a load??? :wink:
Click to expand...

exactly. with the only "loads" being accessory equipment fed from connected "HOUSE" power.

I know it's probably stupid on my part, but I've been trying to determine what size equiment ground, if any, would be required if the only wiring between the generator and facility is the generator output leads.
I've tried to draw-out the current paths and I haver only confused myself.
 
wirenut1980 said:
Although allowed by code to use metallic conduit as the EGC, performance-wise it is best to use an insulated conductor...or even better yet, use the metallic conduit supplemented by an insulated conductor. Just in case Money is no object.:wink:
Click to expand...

You don't want to go through this discussion again--- do you. Or did you miss the last 30 of them. :D
 
augie47 said:
With that in mind, is there any need to pull and equipment ground to the generator larger than the eq. ground needed for charger/control circuit/heater "house" circuits to ground the frame/housing ?
Click to expand...
Yes, it is the only fault clearing path for a generator winding or feeder conductor fault at the generator.
 
If the generator is does not have a bonding connection and is not wired as an SDS, then you must run an EGC to catch the transfer switch and the generator frame. 250.4(A)(5).
 
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