Residential Code 3

[RichardMi]

Is there an NEC requirement that the neutral and ground buses be completely seperate? I looked at a house yesterday that had the neutrals and grounds for the branch circuits all run to the same bus bar.

 

[davidbeach]

At the one point on the system that the neutral is grounded, the neutrals and equipment grounds can land on the same bar. If there were a sub-panel, it would have to have separate bars and the neutral bar would have to be insulated from the panel cabinet.

 

[arango]

from my experience, the electrical code of my country is based on the NEC (it's practically a translation), this code clearly specifies that neutral and ground buses be separated for the branch circuits, so I assume this requirement would apply for the NEC code too.

 

[rmiell]

All electrical services will have the neutrals and the grounds tied together at the main service disconnect. NEC Article 250.24 says "A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).

This is your 1st tie between the two.

After this, Article 250.142 gives the rules for seperating the two. 250.142(B) says "...a grounded circuit conductor shall not be used for grounding non-current-carrying metal part of equipment on the load side of the service disconnecting means..."

With a few exception, every other location will have them seperated. One exception is an existing dryer or range branch circuit. If it is a new branch circuit, it is required to have them seperated. Another exception is a panel in another building, such as a detached garage. This location may or may not have them seperated, depending on a number of things. A subpanel, or a panel that is in the same building as the main service panel, is required to have the 2 seperated, with no exceptions.

A complete reading of Article 250 of the NEC will give you the requirements.

Respectively

Rick Miell