Sizing of grounding conductor

Status
Not open for further replies.
sizing of grounding conductor

sizing of grounding conductor

CHOCHO77

What type of system are we talking about? I'm assuming it is that which is described in 250.24(c). I agree with those who basically said that you wouldn't have a grounding conductor on the line side of the service disconnect. Most service equipment I've seen has the neutral bonded to the case, or the means to bond it. Installing a grounding conductor of the wire type would create parrallel paths for neutral current. And yes you are required to bond one side of a conductive raceway, so the easiest way would be PVC.


hope this was some help


ibew441dc
 
Last edited:
I was with out my regular computer for a while so I forgot about this post.

AS I see it the question is how large the jumper must be if the neutral and CT can are not allready bonded? Even if you bond between the neutral in the CT and the can, what size wire do you use?
Do you have to use 250.66 or can you use 250.122?
I feel 250.66 was writen with the purpose of sizing the Service Grounding Conductor, and the bonding of the Service Grounded Conductor to the Service Grounding Conductor.
Once that is done at the Main over current device, as required, I didn't think 250.66 applied to grounding the CT can.

On smaller services, 250.66 requires larger conductors than 250.122, but on larger services that is reversed.
 
Last edited:
size of grounding conductor

size of grounding conductor

Russ,

I would recommend reviewing 250.24(C)(1) for the minimum size of the grounded conductor brought to service equipment. This clearly states that you would apply 250.66, (not 250.122).

As far as the bonding jumpers are concerned 250.102(C) and (D) are worth taking a look at. The bonding jumpers in this situation would be found in 250.66 based on the phase conductors.

hope this helped

ibew441dc
 
250.102(C) tells us to use Table 250.66 to size bonding jumpers on the supply side of the service. It goes on to require the size of the bonding jumpers to be increased above what 250.66 requires, if the size of the service entrance phase conductors are larger than 1100 kcmil copper or 1750 kcmil aluminum, using the 12 1/2 percent rule.
 
Status
Not open for further replies.
Top