Bonding from subpanel

Status
Not open for further replies.
J

JdoubleU

Senior Member
This project is to install a new service in the garage and turn existing main panel into a subpanel. All of the bonding is done in the subpanel. I understand that this is no problem but the equipment ground is sized differently. I can't remember where this is in the code. I am sure you would size it to table 250.122. What are your thoughts?
 
Jakewhis said:
This project is to install a new service in the garage and turn existing main panel into a subpanel. All of the bonding is done in the subpanel. I understand that this is no problem but the equipment ground is sized differently. I can't remember where this is in the code. I am sure you would size it to table 250.122. What are your thoughts?
Click to expand...

If the panel in the garage contains the new service disconnect then I'd imagine that the main bonding jumper and GEC would need to be properly installed there, and the subpanel would need to have an EGC pulled to it, with separate neutral and ground buses.
 
Notice 250.24(A)(5) "A grounded conductor shall not be connected to normally non-current-carrying metal parts of equipment [bonded]... and 250.142(B) "...a grounded circuit conductor shall not be used for grounding non-current-carrying metal part of equipment [bonded] on the load side of the service disconnecting means..."

The reason is to eliminate parallel neutral current returning to source on paths it does not belong, remember it will fallow all paths according to the levels of resistance not just the path of least resistance.
 
In the sub-panel I will be seperating the neutral and grounds. The water pipes and so forth are bonded from the sub-panel and seperated from the neutral. I just could remember where it was in the code that allows bonding of the water pipe, steal and so forth from the sub-panel. Of course the accual bonding is done at the main. I thought this was allowed as long as the equipment ground going to the sub-panel was sized larger.
 
Take a look at 250.32 for the grounding requirements for separate structures and buildings supplied by a feeder or branch circuit.

Chris
 
Jakewhis said:
In the sub-panel I will be seperating the neutral and grounds. The water pipes and so forth are bonded from the sub-panel and seperated from the neutral. I just could remember where it was in the code that allows bonding of the water pipe, steal and so forth from the sub-panel. Of course the accual bonding is done at the main. I thought this was allowed as long as the equipment ground going to the sub-panel was sized larger.
Click to expand...

If you?re bonding as in 250.104 (which it sounds like you are) you can terminate in the sub panel if the subs feeder equipment ground is large enough, it would be weird if it weren?t. If you?re water pipe is an electrode as in 250.52(A)(1) its conductor must terminate at the service disconnect.

Either way it?s sized from Table 250.66
 
Metallic water pipe generally must be bonded to the service disconnect the only exception is mulit family applications where the water piping systems are isolated from one another then the subpanel of that unit can bond it.
 
Status
Not open for further replies.
Top