grounding for feeder from existing service to boat dock

[CECO]

I am installing feeder from existing service from dwelling to load center at walk way at boat dock. I say the grounded conductor is run w/ feeders and atached to the neutral at load center at walkway. The ground conductor from electrode at walkway is to be connected to ground bar with all grounding condutors to equipment at dock, the ground bar to be isolated from neutral bar at load center. Local "inspector" wants all neutral and grounding tied together. Please state rule of the 2011 NEC that is correct for this situation.

 

[JDBrown]

The relevant NEC article is 250.32 (your dock is likely considered a separate structure).

I thought I knew the answer to your question, but after reviewing 250.32 in the 2008 Handbook, now I'm not so sure. Exhibit 250.17 and the commentary after 250.32(A) show the feeder with NO equipment ground, a new GES at the remote building, and the NG bonding jumper installed in the remote building's panel.

However, then 250.32(B) says that an equipment grounding conductor must be run with the feeder, and the NG bond shall NOT be installed in the remote building's panel. So now I'm confused as to which is correct.

Based on my understanding of NEC 250.32, you need a new GES at your dock (probably a pair of ground rods), and your EGC from the source panel and GEC from the new ground rods will land on your ground bus. Your NG bond should NOT be installed.

That lousy commentary after 250.32(A) has me doubting myself, though. Maybe somebody else can chime in and clarify some more.

 

[GoldDigger]

I am installing feeder from existing service from dwelling to load center at walk way at boat dock. I say the grounded conductor is run w/ feeders and atached to the neutral at load center at walkway. The ground conductor from electrode at walkway is to be connected to ground bar with all grounding condutors to equipment at dock, the ground bar to be isolated from neutral bar at load center. Local "inspector" wants all neutral and grounding tied together. Please state rule of the 2011 NEC that is correct for this situation.

Is your "feeder" really a feeder whose source is after the main service disconnect, or is it an extension of the service wiring?
If it is a feeder, you must run an EGC along with the grounded wire.
If if is an extension of the service, then the inspector is right and you need to use a service rated new panel and wire it just as you would a single main panel.

 

[hornetd]

Is your "feeder" really a feeder whose source is after the main service disconnect, or is it an extension of the service wiring?
If it is a feeder, you must run an EGC along with the grounded wire.
If if is an extension of the service, then the inspector is right and you need to use a service rated new panel and wire it just as you would a single main panel.

The wiring to the dock's panel is Service entry conductors only if the service disconnecting means is located at the dock. If there is a disconnecting means located at the dwelling then the supply conductors to the dock are a feeder. The dock panel is a feeder supplied lighting and appliance panel if there is any customer operable disconnecting means at the building from which the supply conductors are run.

 

[augie47]

Be aware your inspector may enforce Art 692 also.

 

[texie]

I am installing feeder from existing service from dwelling to load center at walk way at boat dock. I say the grounded conductor is run w/ feeders and atached to the neutral at load center at walkway. The ground conductor from electrode at walkway is to be connected to ground bar with all grounding condutors to equipment at dock, the ground bar to be isolated from neutral bar at load center. Local "inspector" wants all neutral and grounding tied together. Please state rule of the 2011 NEC that is correct for this situation.

You need to comply with 250.32(A) and 250.32(B)(1). You don't mention if you have an EGC run with the feeder. You are required to have an EGC run with the feeder, a grounding electrode system connected to the ground bar of the dock panel and absolutely do not bond the neutral.
If you did not run an EGC with the feeder this installation can't be made compliant under the NEC starting with the 2008 edition.