Neutrals and Grounds

[Ty Lippert]

Been a member for a while. First post. I am a Home Inspector in WI and have an electrical question. Is it EVER EVER OK to have a neutral wire http://www.inspectionnews.net/home_inspection/attachment.php?attachmentid=35112&stc=1and ground wire under the same screw on a busbar in the service panel. ("main") I called this out on an inspection recently, as I always do, and recommended and electrician repair this defect. The electrician they hired to repair it sent a letter to the real estate agent saying the screws on the bus are rated for up to 3 wires, so there were no defects in the panel. But only 3 ground wires per screw, correct? Each neutral is to have its own screw, Correct? Just want to make sure. Thanks in advance. http://www.inspectionnews.net/home_inspection/attachment.php?attachmentid=35112&stc=1

[Jerry Peck]

No. The neutral needs to be in its own terminal.

Most modern (in the last 20-25 years or so) state that grounding terminals are rated for two conductors (groundING conductors, not groundED conductors). The panel label will state whether 1, 2, or more are allowed.

Neutral (groundED) conductors are required to be one per terminal.

[Ty Lippert]

No. The neutral needs to be in its own terminal.

Most modern (in the last 20-25 years or so) state that grounding terminals are rated for two conductors (groundING conductors, not groundED conductors). The panel label will state whether 1, 2, or more are allowed.

Neutral (groundED) conductors are required to be one per terminal.


Thank You Jerry.

[Gunnar Alquist]

Ty,

To expand on what Jerry has already said. It looks like the problem is in the way many electricians (and building inspectors) have historically interpreted 110.14 in the NEC. Remember, the NEC is largely permissive. It's easier to say what is allowed than to say what is not allowed.

NEC 110.14 (A) Terminals. Terminals for more than one conductor and terminals used to
connect aluminum shall be so identified.

The NEC is not saying that multiple conductors are allowed at a terminal. It is essentially saying that more than one conductor at a terminal is up to the manufacturer. So, we go to the data plate/label on the panel (which, unfortunately is often no longer there). The included pic is of a data plate/label that I took from some service equipment a while ago. You can see the wording:

"When used as service equipment, any unused neutral wire holes may be used for equipment grounding. Small wire holes are suitable for..."

Here, the manufacturer is saying that multiple equipment grounding conductors are acceptable (and provides specifics). Permission has not been given for multiple neutral (grounded) conductors under a single terminal screw. Unfortunately, many misinterpreted this to mean that you could.

Then, I think it was in the 2005 NEC, (probably because 110.14 (A) was so commonly misinterpreted), 408.41 was added.

408.41 Grounded Conductor Terminations. Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor.

As long as the electrician understands the difference between "grounded" and "grounding", this should make it pretty darned clear.

[Ty Lippert]

Ty,

To expand on what Jerry has already said. It looks like the problem is in the way many electricians (and building inspectors) have historically interpreted 110.14 in the NEC. Remember, the NEC is largely permissive. It's easier to say what is allowed than to say what is not allowed.

NEC 110.14 (A) Terminals. Terminals for more than one conductor and terminals used to
connect aluminum shall be so identified.

The NEC is not saying that multiple conductors are allowed at a terminal. It is essentially saying that more than one conductor at a terminal is up to the manufacturer. So, we go to the data plate/label on the panel (which, unfortunately is often no longer there). The included pic is of a data plate/label that I took from some service equipment a while ago. You can see the wording:

"When used as service equipment, any unused neutral wire holes may be used for equipment grounding. Small wire holes are suitable for..."

Here, the manufacturer is saying that multiple equipment grounding conductors are acceptable (and provides specifics). Permission has not been given for multiple neutral (grounded) conductors under a single terminal screw. Unfortunately, many misinterpreted this to mean that you could.

Then, I think it was in the 2005 NEC, (probably because 110.14 (A) was so commonly misinterpreted), 408.41 was added.

408.41 Grounded Conductor Terminations. Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor.

As long as the electrician understands the difference between "grounded" and "grounding", this should make it pretty darned clear.
Thank you Gunner.

[david shapiro]

One rationale behind this is that if you want to remove a 120V or 240/120 circuit, you turn off and remove the CB or CBs before you remove the groundED/neutral conductor, so it's not carrying current. Well dang, if the hole it's in is another circuit's return path, if current's flowing on that circuit, you've got maybe sparks, you've got transients hitting equipment, all that unnecessary stuff.