Thread: separating grounds and neutrals in service panel

I was told today by a local AHJ that the NEC now requires grounds and neutrals to be placed on separate bars in the service panel. I had noticed new construction frequently done this way but as always it seems so do, some don't, so what. This is not to be confused with isolating grounds and neutrals in remote panels. Is he right if so please refer to section in NEC.

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News to me and I have not seen anything in the trade magazines either.

Originally Posted by Don Hawley

I was told today by a local AHJ that the NEC now requires grounds and neutrals to be placed on separate bars in the service panel. I had noticed new construction frequently done this way but as always it seems so do, some don't, so what. This is not to be confused with isolating grounds and neutrals in remote panels. Is he right if so please refer to section in NEC.

Originally Posted by Jim Port

News to me and I have not seen anything in the trade magazines either.

Like many things with codes, I suspect the correct answer is - It depends.

I suspect that the information has lost some in communication from person to person to person, like the old game of Telephone - where the first person in the circle whispers a word or phrase into the ear of the person to their right. The Game Continues as players whisper the phrase to their neighbors until it reaches the last player in line, who then states what they were told, and compares it to what the first person said - what the last person was told seldom resembles the first person said.

The neutrals are to be connected to the neutral terminal bar, the grounds are to be connected to the ground terminal bar, and - in many panels - BOTH terminal bars are neutral/ground terminal bars ... however ... in some panels, the neutral is connected to the neutral terminal bar and there is not a full sized/rated jumper/connector to the ground terminal bar - in those panels - the neutrals are not permitted on the ground terminal bar.

That is shown in the schematic on the label, so you would need to read the label to know what was permitted/not permitted for that panel.

Just guessing what is being referred to.

Neutral would not be permitted on a ground bar with a properly sized jumper. Ground bars are for grounding conductors only.

Originally Posted by Jim Port

Neutral would not be permitted on a ground bar with a properly sized jumper. Ground bars are for grounding conductors only.

Define a "ground bar".

Many panels have terminal bars which serve as both neutral and ground terminal bars, and thus are "ground bars" as well as "neutral bars".

Neutrals are permitted on those "ground bars".

The instructions say that unused holes in the neutral bar may be used for grounding conductors.

Ground bars are attached to the enclosure and no neutrals are allowed in those.

Originally Posted by Jim Port

Neutral would not be permitted on a ground bar with a properly sized jumper. Ground bars are for grounding conductors only.

Originally Posted by Jim Port

Ground bars are attached to the enclosure and no neutrals are allowed in those.

Thus there would not be a jumper from the neutral to the ground bar - those would be "Equipment Ground Only" bars, which are not what I am referring to.

A neutral bar that allows grounding conductors is not a ground bar. It remains a neutral bar. The grounding conductor terminations do not change the part name. The label calls it a neutral bar.

Originally Posted by Jim Port

A neutral bar that allows grounding conductors is not a ground bar. It remains a neutral bar. The grounding conductor terminations do not change the part name. The label calls it a neutral bar.

The labels I recall seeing label it as a neutral / ground bar as it designates it as being suitable for both.

A neutral-only bar which is not a neutral / ground bar is one in which the neutral is isolated from ground.

A ground-only bar which is not a neutral / ground bar is one which is solidly attached to the enclosure with screws ... unless the equipment is labeled "Suitable Only For Use As Service Equipment" or similar wording, such as "Suitable for Service Equipment Use Only". Few panels are labeled as "only" being suitable for use as service equipment today, most are labeled as being "Suitable For Use As Service Equipment" (the panel is suitable for use as service equipment when the neutral-to-ground bonding is done, and when there is a main when more than 6 disconnects are present).

Just a home owner here with some electrical education ...

My home's service panel had to have the neutrals and grounds separated after a generator and transfer switch were added a few years ago. The transfer switch was interposed between the meter and what had been, until then, the service panel. It is now just a panel. The neutral bar had the bonding screw or jumper removed so that it is no longer connected to the case of the panel itself or the ground bar.

Service equipment is, I believe, defined as the first disconnect or breaker after the meter. In my case it's now the main breaker on the incoming utility power in the transfer switch enclosure. Neutral and ground are supposed to be bonded only at one point after the meter - in the service panel. In my case that's the transfer switch enclosure and that is why they are now separated in the former main panel.

The contractor who built the house made the later change easy by keeping the neutrals and grounds on the separate bars in what was then the service panel.