Neutral and ground separation in remote panels

[Trent Tarter]

I was talking with an experienced electrician today and would like some additional clarification. It was always my understanding that ground wires had to be separated from neutrals and bonded to panel in any remote distribution panels (aka sub panel). I was told by the electrician that it's only required when the downstream panel is located in the home, and that remote panels in any detached outbuilding do not require the grounds to be separated.

The photo is a remote panel in detached garage, it's fed from the home's main service panel.

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[Jim Katen]

Before the 2008 NEC, separate buildings could be fed with a three-wire feeder (no equipment grounding conductor) if certain conditions existed. Even then, however, if a 4-wire feeder was installed, you had to keep the grounds isolated from the neutrals.

Since 2008, all new feeders to separate buildings require four-wire feeders and separation between the grounds and neutrals.

Perhaps your electrician is old and hasn't kept up with the changes in the last few code cycles.

[Trent Tarter]

Before the 2008 NEC, separate buildings could be fed with a three-wire feeder (no equipment grounding conductor) if certain conditions existed. Even then, however, if a 4-wire feeder was installed, you had to keep the grounds isolated from the neutrals.

Since 2008, all new feeders to separate buildings require four-wire feeders and separation between the grounds and neutrals.

Perhaps your electrician is old and hasn't kept up with the changes in the last few code cycles.

Yes he's an older electrician that just happens to be the president for a large electrical contractor. I doubt he does much active electrical work, pretty much has an office job. I need to find the actual code so I can prove I was correct in what I called out.

[Jim Katen]

Yes he's an older electrician that just happens to be the president for a large electrical contractor. I doubt he does much active electrical work, pretty much has an office job. I need to find the actual code so I can prove I was correct in what I called out.

250.32(B)(1)

(B) Grounded Systems.

(1) Supplied by a feeder or branch circuit. An equipment grounding conductor, as described in 250.118, shall be run with the supply conductors and be connected to the building or structure disconnecting means and to the grounding electrode(s). The equipment grounding conductor shall be used for grounding or bonding of equipment, structures, or frames required to be grounded

or bonded. The equipment grounding conductor shall be sized in accordance with 250.122. Any installed grounded conductor shall not be connected to the equipment grounding conductor or to the grounding electrode(s).

An exception follows for existing installations where there's no equipment grounding conductor as part of the feeder and where there are no continuous metallic paths bonded to the grounding system in each structure and where there's no GFCI protection on the supply side of the feeder.

[Trent Tarter]

What I'm trying to find is something that mentions that neutral wires should be on a "floating bus bar" and that all ground wires should be bonded directly to the panel and/or isolated from neutrals.

[Mark P]

National Electric Code, section 408.41; reads "Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor".

First published in the 2002 NEC 408.21; moved to 408.41 in 2008.

[Jim Katen]

What I'm trying to find is something that mentions that neutral wires should be on a "floating bus bar" and that all ground wires should be bonded directly to the panel and/or isolated from neutrals.

The reference that I gave you says that.

Mark's reference has to do with double tapping.

[mlparham]

Before the 2008 NEC, separate buildings could be fed with a three-wire feeder (no equipment grounding conductor) if certain conditions existed. Even then, however, if a 4-wire feeder was installed, you had to keep the grounds isolated from the neutrals.

Since 2008, all new feeders to separate buildings require four-wire feeders and separation between the grounds and neutrals.

Perhaps your electrician is old and hasn't kept up with the changes in the last few code cycles.

I'm a little confused. I think I remember you saying in past posts that the NEC has required ground and neutral separation in subpanels since the 30's.

[Mark P]

National Electric Code, section 408.41; reads "Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor".

First published in the 2002 NEC 408.21; moved to 408.41 in 2008.

Sorry I guess I had my wires crossed. haha. This is not the answer to your questions.

[Jim Katen]

Before the 2008 NEC, separate buildings could be fed with a three-wire feeder (no equipment grounding conductor) if certain conditions existed. Even then, however, if a 4-wire feeder was installed, you had to keep the grounds isolated from the neutrals.

Since 2008, all new feeders to separate buildings require four-wire feeders and separation between the grounds and neutrals.

Perhaps your electrician is old and hasn't kept up with the changes in the last few code cycles.

I'm a little confused. I think I remember you saying in past posts that the NEC has required ground and neutral separation in subpanels since the 30's.

Not in separate buildings.

[LeePlace]

Jim,

It appears to be a 4 wire feed. According to your post the grounded conductors should be isolated from the enclosure and grounding conductors.

Lee

[Jim Katen]

Jim,

It appears to be a 4 wire feed. According to your post the grounded conductors should be isolated from the enclosure and grounding conductors.

Lee

Yes. Absolutely. Do my posts seem to indicate otherwise?