Neutral buss in different cabinet than breakers??

[Strombea]

I have a sub panel to move 200' as the original design was terrible. Customer is asking me to relocate it. Instead of taking all neutrals and grounds 200' longer, my question is can I just extend the line sides almost like a switch leg. I would still bring a feeder neutral for future loads from the new location. I will placard on both panels the location of neutral and ground buss bars. NEC ref would help too.

 

[winnie]

What you are asking to do is create a 'common neutral' circuit where a bunch of different 'hot' conductors share a single neutral conductor. Note, this is not a MWBC, but something even more general. You could have a large number of 'hots' on different or the same phases, all sharing a neutral that was sized for the largest possible unbalanced load. This _might_ have been legal in the past, but is most likely not practical even if there were some set of hoops you could jump through to do a legal install.

In the past these sort of common neutral circuits were explicitly permitted for _outside_ branch circuits, but were not mentioned at all in article 210 for inside branch circuits, so they _might_ have been legal.

It is a requirement that the neutral for a circuit be in the same raceway or conduit as the circuit conductors. So you couldn't go from your new subpanel to your loads and then have the neutral return to the old subpanel. All of the circuit hot conductors and this hypothetical common neutral would go from the new subpanel to the old subpanel in a single raceway, then the common neutral would 'branch out' at the old subpanel. This would probably mean a bunch of derating issues unless there were not many circuits.

I believe that under current rules for MWBCs, you would be forced to put some sort of handle tie on all breakers which share a neutral. This would again make a common neutral solution impractical for more than a few circuits.

I recall that there was a code change prohibiting common neutral circuits in outdoor applications. Not sure if this was explicit for indoor applications. But again even if such circuits are legal, code requirements probably make them impractical.

You are probably better off simply installing the new subpanel at the correct location, and then running new circuits from the new location to the loads.

-Jon

 

[James L]

I have a sub panel to move 200' as the original design was terrible. Customer is asking me to relocate it. Instead of taking all neutrals and grounds 200' longer, my question is can I just extend the line sides almost like a switch leg. I would still bring a feeder neutral for future loads from the new location. I will placard on both panels the location of neutral and ground buss bars. NEC ref would help too.

Are you moving the subpanel, or leaving the existing subpanel in place and adding a subpanel?

Sounds like adding one. How will you connect the feeder? Put a breaker in the existing panel?

 

[kwired]

See 300.3(B), and subsection (4).

I think the main idea is not to have magnetic effects surrounding the conductors, which you wouldn't have if you ran a common neutral to a pull box then split it for specific branches, but it seems to only be permitted in the situation mentioned in (4). Any other way of doing that sort of thing is mostly seen as an improper way to utilize multiwire branch circuits in accordance with 210.4.

 

[Todd0x1]

Wait so you're moving an existing panel 200ft and extending the existing branch circuits 200ft as well? Are you going to have voltage drop issues on those branch circuits? How many are there? Are they in pipe or cable?

 

[Strombea]

I am moving the panel about 160 feet and right now all the homeruns these are storage units are in MC cable back to the sub panel that's existing I am going to take two runs of 2 inch pipe one for the feeders and one for all of the hots to backfeed from my new sub panel to my J box where all the homeruns will just wire nut through

 

[Strombea]

Are you moving the subpanel, or leaving the existing subpanel in place and adding a subpanel?

Sounds like adding one. How will you connect the feeder? Put a breaker in the existing panel?

I could do that but my plan was to basically use Polaris plugs and take all the guts out of the old panel feed the feeders through and basically use the old panel just as a J box with the neutral bus still in tact so I don't have to extend the neutrals only the hots to the new breaker location

 

[Todd0x1]

I am moving the panel about 160 feet and right now all the homeruns these are storage units are in MC cable back to the sub panel that's existing I am going to take two runs of 2 inch pipe one for the feeders and one for all of the hots to backfeed from my new sub panel to my J box where all the homeruns will just wire nut through

yeah...uh you can't do that.

Also, how many circuits are there? You'll probably run into a derating issue putting all your circuits in one pipe.

 

[synchro]

What is the problem with the present location of the subpanel for the customer, and what advantage does the new location provide him or her? Is it to provide easier access for turning the power ON / OFF to individual storage units?

 

[Fred B]

This would be a violation of 200.4(A) "Installation. Neutral conductors shall not be used for more than one brach circuit, for more than one multi wire branch circuit, or for more than one set of ungrounded feeder conductors unless specifically permitted elsewhere in this Code." And the exceptions listed would not apply.
So

I have a sub panel to move 200' as the original design was terrible. Customer is asking me to relocate it. Instead of taking all neutrals and grounds 200' longer, my question is can I just extend the line sides almost like a switch leg. I would still bring a feeder neutral for future loads from the new location. I will placard on both panels the location of neutral and ground buss bars. NEC ref would help too.

Can't be done and be code compliant. You can do as suggested with the grounds but there are additional requirements to do that.

 

[winnie]

I could do that but my plan was to basically use Polaris plugs and take all the guts out of the old panel feed the feeders through and basically use the old panel just as a J box with the neutral bus still in tact so I don't have to extend the neutrals only the hots to the new breaker location

Okay, Fred B listed the new code that I didn't remember. You are not permitted to do what you describe.

The feeder to the new panel will need to be complete with the neutral and the circuits back from the new panel will need to be complete with their neutrals.

Jon

 

[kwired]

Okay, Fred B listed the new code that I didn't remember. You are not permitted to do what you describe.

The feeder to the new panel will need to be complete with the neutral and the circuits back from the new panel will need to be complete with their neutrals.

Jon

It not that new. late 80's early 90's I had boss that used to run a large neutral and multiple ungrounded conductors, from theory perspective it works, but way back then we had an inspector call out same code as a reason to not do it this way. I don't know if there was code change back around that time, but it is when it was pointed out you can't do it that way.

 

[winnie]

As I mentioned in post 2, in the past these common neutral circuits were explicitly permitted in article 225 for _outside_ branch circuits, but not mentioned at all for _inside_ branch circuits. Some people took this lack of explicit permission for _inside_ branch circuits as a meaning that you could not use them inside. Other people noted that if the code doesn't prohibit something then it is permitted.

So the use of these common neutral circuits _inside_ was debatable until 200.4(A) made it explicit that they were not permitted. This happened some time after the 2002 edition of the code.

-Jon

 

[Strombea]

All feeder neutrals are feeding a buss bar with lots of other neutrals on it so??? This neutral feeder is still feeding the ungrounded feeder conductors that are with it. The hot side just happens to be a little bit longer. Electrically nothing has changed except maybe voltage drop which can be accounted for. I think the code you are referencing is to make sure that one neutral conductor is not feeding more than a multi wire branch circuit. Obviously this neutral is not getting an added load by doing this.

300.3B4 I think would allow neutrals to "Originate" in the pull box.

The original question is simply about a neutral bus in a gutter, pull box or J box obviously conduit fill voltage drop and De-rating would still be very important

This would be a violation of 200.4(A) "Installation. Neutral conductors shall not be used for more than one brach circuit, for more than one multi wire branch circuit, or for more than one set of ungrounded feeder conductors unless specifically permitted elsewhere in this Code." And the exceptions listed would not apply.
So

Can't be done and be code compliant. You can do as suggested with the grounds but there are additional requirements to do that.

 

[Fred B]

All feeder neutrals are feeding a buss bar with lots of other neutrals on it so??? This neutral feeder is still feeding the ungrounded feeder conductors that are with it. The hot side just happens to be a little bit longer. Electrically nothing has changed except maybe voltage drop which can be accounted for. I think the code you are referencing is to make sure that one neutral conductor is not feeding more than a multi wire branch circuit. Obviously this neutral is not getting an added load by doing this.

300.3B4 I think would allow neutrals to "Originate" in the pull box.

The original question is simply about a neutral bus in a gutter, pull box or J box obviously conduit fill voltage drop and De-rating would still be very important

300.3(B)(4) is specific to: "Column Width Panelboard Enclosures. Where an auxiliary gutter runs between between a column-width panelboard and a pull box, and the pull box includes neutral terminations, the neutral conductors of circuits supplied from the panelboard shall be permitted to originate in the pull box."
1. The OP does not mention a column width panelboard
2. Maybe someone can inform me but unaware of a 200ft auxiliary gutter.
3. See 366 Auxiliary Gutter. 366.2 Definitions.
4. See 366.12(2) Uses not permitted. "To extend a greater distance than 9 m (30 ft) beyond the equipment it supplements."
5. Exception listed to 366.12(2) only applies to use in relationship to elevators as permitted in 620.35

So I don't see your listing of 300.3(B)(4) as allowing your suggested wireing method as it suggests extending circuits 200 ft. As well as not relating to the specific equipment listed in code section.