More Double Tap Fun.....

[Michael Larson]

ound this yesterday. I know this issue is frequently discussed but haven't seen this particular situation on the board recently. I'm tossing it out here for comment and discussion. Share your thoughts. The panel installation sure looked pretty.

[Jeffrey R. Pope]

Connection of the neutral and grounding conductors under the same lug/terminal has never been allowed.

I wouldn't call this a "double tap," I would just call it "wrong."

[Larry D. Kage]

Agreed...from Mike Holt's site:

[Greg Fretwell]

This has never been legal but it is very common. When these are both on the same circuit it is not a particular hazard but it is still wrong.
The real "douple lug neutral" thing addresses having to disturb one circuit to work on another. It is similar to the requirement about pigtailing multiwire neutrals.

[Larry D. Kage]

Originally Posted by Greg Fretwell

This has never been legal but it is very common. When these are both on the same circuit it is not a particular hazard but it is still wrong.
The real "douple lug neutral" thing addresses having to disturb one circuit to work on another. It is similar to the requirement about pigtailing multiwire neutrals.

Good info Greg. That's why I underlined some text in the attachment.

Such as:
Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor.

[Michael Larson]

Originally Posted by Greg Fretwell

This has never been legal but it is very common. When these are both on the same circuit it is not a particular hazard but it is still wrong.
The real "douple lug neutral" thing addresses having to disturb one circuit to work on another. It is similar to the requirement about pigtailing multiwire neutrals.

I agree. It presents no real "hazard" but it does not agree with the code in section 408.21. Its frustrating when the manufacturer seems to indicate its permissible by the following text on the panel door.


Read the line that begins "When used as service equipment...."

What have you done when you have seen this wiring method?

[Brian E. Kelly]

Originally Posted by mlarson

I agree. It presents no real "hazard" but it does not agree with the code in section 408.21. Its frustrating when the manufacturer seems to indicate its permissible by the following text on the panel door.
Attachment 4330

Read the line that begins "When used as service equipment...."

What have you done when you have seen this wiring method?

Did I read that wrong, does it say "Any unused nuetral holes may be used for equipment grounds"?

[Greg Fretwell]

Yes that is what it says. Note it doesn't say you can stick neutrals in spare ground bus holes.

extra credit for the first person who knows why (code wise)

[Brian E. Kelly]

Originally Posted by Greg Fretwell

Yes that is what it says. Note it doesn't say you can stick neutrals in spare ground bus holes.

That's funny.

[Larry D. Kage]

Originally Posted by mlarson

I agree. It presents no real "hazard" but it does not agree with the code in section 408.21. Its frustrating when the manufacturer seems to indicate its permissible by the following text on the panel door.
Attachment 4330

Read the line that begins "When used as service equipment...."

What have you done when you have seen this wiring method?

Michael, I'm not following you. Grounding conductors can have more than one conductor under a lug screw, as/when stated on the panel board label, but grounded wires cannot.

Is that what you mean?

[Michael Larson]

Originally Posted by bkelly2

Did I read that wrong, does it say "Any unused nuetral holes may be used for equipment grounds"?

That's what it says, Though that's only for 'Service Equipment" use

Otherwise the left bar is ground and the right bar is Neutral if the jumper is not in place in this panel.

[Michael Larson]

Originally Posted by lkage

Michael, I'm not following you. Grounding conductors can have more than one conductor under a lug screw, as/when stated on the panel board label, but grounded wires cannot.

Is that what you mean?

Open the attachment in Larry's post #3. That graphic makes it very clear. Sorry for any confustion. Grounded conductor is the term for "Neutral".

[Robert J. OConnor]

I think a neutral and ground wire on a single lug is just as much of an issue/defect as double lug neutrals or hot wires. Part of the problem with conductors that regularly carry significant current is wire to wire contact that causes an inferior electrical connection (as opposed to one wire per terminal with good contact against the set screw and lug where the wire is compressed). While the ground wire doesn't regularly carry current, the neutral wire most likely does since it's for a house.

I would write it up the same way, and call it a day

JMO & 2-nickels ...

[Robert J. OConnor]

Originally Posted by bkelly2

Did I read that wrong, does it say "Any unused neutral holes may be used for equipment grounds"?

So the opposite of unused equipment ground holes being used for neutral wires isn't specifically allowed ... so it should't be done (often is though).

Originally Posted by Greg Fretwell

Note it doesn't say you can stick neutrals in spare ground bus holes ... extra credit for the first person who knows why (code wise)

I'm assuming thats because neutral wires in a house normally carry current, where you want a more direct connection between the circuit neutral wire and the service entrance neutral wire (which should be directly connected to the neutral buss).

Also, if ya have a neutral on the grounding buss and there is a problem with the buss strap or bonding lugs, there may be a hot circuit that appears to be dead, which could be a hazard (similar to the reason fused neutrals are not allowed any more).

It's always good to understand the reason behind code/labeling provisions ...

[P.S. How many times have ya seen neutrals on the ground buss in a service panel, or the service entrance feeder neutral wire connected to the ground buss lug ... ]

[Greg Fretwell]

Yup that's it. If you attach a neutral to the grounding bus you get neutral current through the main bonding jumper and that is "objectionable current over the grounding conductors" 250.6(A)