Ground and Neutral under same lug

rslocum · March 14, 2015, 12:33pm

OK , yesterdays inspection , I had a ground and a neutral from the same circuit under one screw in the Main Service Panel. Is this ok ? First time I have seen this, usually grounds and neutrals are separated .

Thanks in advance , Rick

kramm · March 14, 2015, 12:59pm

That’s funny because I see this almost daily. No, they should be separated.
here it what I write.
Neutral (white wire) and equipment grounding conductors (bare wire) terminate under the same lug. An individual terminal should be provided for the connection of each branch-circuit neutral conductor. When the neutral is disconnected, the objective is to still have the equipment ground connected. If both the neutral and grounded conductor is under the same terminal, this cannot be accomplished. Recommend repair by a licensed electrical contractor.

rmeier2 · March 14, 2015, 2:39pm

Although this was a common practice for decades (especially when panelboards didn’t have enough terminal holes) it has never been permitted. To make that point even clearer the NEC added this to the wording in the code:

mbrooke · March 14, 2015, 3:26pm

Not allowed, one neutral per hole, you may double up on grounds provided instructions (panel labels) say so.

Is this panel GE? I see it frequently in older panels, Square D QO is the biggest offender followed by GE where those panels had limited neutral terminals to start with so doubling up was very common.

The reason behind not allowing doubling up (among isolating circuits) is that one conductor may be held in place more by the screw than the other conductor. This can cause further loosening and overheating down the road.

Steve_Man · March 14, 2015, 6:04pm

Which would be correct Martin

The actual code being>

But the thing is, it was not always in the NEC .

I’m too lazy to look, but i want to say 3-4 code cycles or so

Which means older installs are compliant , under the cycle they were wired

This is an important point because older gear usually doesn’t accommodate what newer gear would.

~S~

rslocum · March 14, 2015, 7:24pm

Thank you Gentleman ! As always , I appreciate you sharing your knowledge!

rmeier2 · March 14, 2015, 8:10pm

Not exactly, this was already prohibited by the listing of the panelboard. It was only added to the 2002 NEC because no one actually knew about the listing violation.

rmeier2 · March 14, 2015, 8:18pm

Here’s the original ROP for that language to be inserted into the NEC for anyone interested, this was later moved to Article 408 when they reshuffled the Article numbers in the 2002. The substantiation provided by Square D is worth reading.

9- 113 - (384-21 (New) ): Accept
SUBMITTER: James T. Pauley, Square D Co.
RECOMMENDATION: Add a new 384-21 to read as follows:
384-21. Grounded Conductor Terminations. Each grounded
conductor shall terminate within the panelboard in an individual
terminal that is not also used for another conductor.
Exception: Grounded conductors of circuits with parallel
parallel shall be permitted to terminate in a single terminal if the
terminal is identified for connection of more than one
conductor.
SUBSTANTIATION: This revision is needed to coordinate the
installation requirements with a long standing product standard
requirement. Clause 12.3.10 of UL 67 (Panelboards) states “An
individual terminal shall be provided for the connection of each
branch-circuit neutral conductor.” The requirement has been
enforced in the past by a close review of the manufacturers
markings and by NEC 110-3(b). However, since it is a rule that
specifically effects how the installer can make connections, it is
important that it be in the NEC.
Even with the manufacturers markings, inspectors still indicate
that they see a number of panelboards installed with two (or
more) branch circuit neutrals under one terminal or they see an
equipment grounding conductor and neutral under the same
terminal.
There is very good rationale for the requirement in the product
standards. Doubling up on the neutrals creates a significant
problem when the circuit needs to be isolated. In order to
isolate the circuit, the branch breaker is turned off and the
neutral is disconnected by removing it from the terminal. If the
terminal is shared with another circuit, the connection on the
other (still energized) circuit will be loosened as well. This can
wreak havoc, particularly if the neutral is part of a 120/ 240V
multi-wire branch circuit. Also, the neutral assemblies are not
evaluated with doubled-up neutrals in the terminals.
The connection of a neutral and equipment grounding
conductor creates a similar issue. One of the objectives of the
particular arrangement of bonding jumpers, neutrals and
equipment grounds is to allow circuit isolation while keeping the
equipment grounding conductor still connected to the grounding
electrode (see UL 896A - Reference standard for Service
Equipment). When the neutral is disconnected, the objective is
to still have the equipment ground solidly connected to the
grounding electrode. If both the neutral and grounded
conductor are under the same terminal, this cannot be
accomplished.
This addition to the NEC does not change any product or
permitted wiring arrangement from what it is today. It will
however, it will help installers to avoid wiring the panel in
violation of 110-3(b) and then have to contend with a red-tag
from the inspector.
The code language is proposed in a fashion to allow consistent
enforcement of the provision the the AHJ. Although the UL
wording is adequate for the product standard, it is important that
the NEC language is as clear an unambiguous as possible. This is
the reason for specifically noting that the terminal cannot be used
for another conductor. Furthermore, the code requirement has
been worded to make sure that both branch circuit and feeder
neutrals are covered since it is not uncommon to have feeder
breakers as well as branch breakers in the panelboard (the issue
for the neutral is the same regardless of branch or feeder). Also,
the term “grounded conductor” is used to be consistent with the
code terminology and to recognize that not all grounded
conductors are neutrals.
An exception has been proposed to avoid any confusion relative
to parallel circuit arrangements. In these instances, multiple
neutrals could be in a single terminal if the terminal has been
identified as acceptable for multiple conductors.
PANEL ACTION: Accept.
In the proposed exception, change the second instance of the
word “parallel” to “conductors”.
PANEL STATEMENT: The correction of the typographical error
meets the intent of the submitter.
NUMBER OF PANEL MEMBERS ELIGIBLE TO VOTE: 11
VOTE ON PANEL ACTION:
AFFIRMATIVE: 11

mbrooke · March 14, 2015, 8:50pm

You are indeed be correct.

If I may, and I know I can be wrong, most older panel boards disallowed it via labelling rather than code; but I may have to double check that now.

Thank you for peaking my curiosity!

Edit: Robert, thank you for the ROP quote. That is exactly what I was thinking of but could not find it.