Can't find actual codes against this

[jap]

I agree, if the field wiring was correct and compliant as 2 separate MWBCs (1,3,5 and 7,9,11) then there is no reason to change the field wiring in order to combine the circuits.

Rather than supplying all of the original 1,3,5,7 conductors from breaker 1, I would have supplied 1 and 7 from breaker 7...3 and 9 from breaker 9, and 5 and 11 from breaker 11.

This would free up the same number of breakers, keep loads distributed on the supply phases and on the field neutrals, keep the facility color code intact, and possibly save a wirenut

-Jon

I disagree.

If you did that you'd still have to change the neutral connections in the field or you would be creating parallel return paths since the return current would be coming back on 2 different neutrals.

For example:
if you turned on breaker 7 as you have it, the return current from circuit 1 would be coming back on the original neutral for 1,3 &5 and the return current for circuit 7 would be coming back on the original neutral for cirucuit 7,9 &11.

JAP>

 

[jap]

at least I think.



JAP>

 

[winnie]

For example:
if you turned on breaker 7 as you have it, the return current from circuit 1 would be coming back on the original neutral for 1,3 &5 and the return current for circuit 7 would be coming back on the original neutral for circuit 7,9 &11.

JAP>

You answered this in post #18.

If the originally completely separate MWBCs are now combined on the breaker, then current flowing out on the _original_ circuit 1 hot will return on the original circuit 1 neutral, and current flowing out on the original circuit 7 hot will return on the original circuit 7 neutral.

In the sense of 'parallel loads', the above makes the original 1,3,5 a parallel to 7,9,11, in the exact same way that two lamps on the same circuit are parallel loads.

But current flowing out on the original circuit 1 hot will not suddenly start returning on the original circuit 7 neutral, not even in part. The original 1,3,5 neutral will not become a parallel conductor with the 7,9,11 neutral.

-Jon

 

[jap]

You answered this in post #18.

If the originally completely separate MWBCs are now combined on the breaker, then current flowing out on the _original_ circuit 1 hot will return on the original circuit 1 neutral, and current flowing out on the original circuit 7 hot will return on the original circuit 7 neutral.

In the sense of 'parallel loads', the above makes the original 1,3,5 a parallel to 7,9,11, in the exact same way that two lamps on the same circuit are parallel loads.

But current flowing out on the original circuit 1 hot will not suddenly start returning on the original circuit 7 neutral, not even in part. The original 1,3,5 neutral will not become a parallel conductor with the 7,9,11 neutral.

-Jon

There is just no need for 2 return neutrals to the panel which is what they have if they didn't change it over in the field.

JAP>

 

[jap]

If you combine 1&7 3&9 and 5&11 on breakers 7,9 &11 you only need 1 neutral return wire is all I'm getting at.

As it is now, without changing it in the field, they are using 2 neutral return wires to the panel.

JAP>

 

[winnie]

I absolutely agree, there is no need for 2 neutrals once the circuits are combined. There is also no need for separate hots on any given phase once the circuits have been combined.

However as long as those neutrals are not connected together downstream in the field wiring, there is also no need to remove them. And it is less work (and allows for future expansion) to leave them in place. Now if you needed space in that conduit for some reason...

-Jon

 

[jap]

I absolutely agree, there is no need for 2 neutrals once the circuits are combined. There is also no need for separate hots on any given phase once the circuits have been combined.

However as long as those neutrals are not connected together downstream in the field wiring, there is also no need to remove them. And it is less work (and allows for future expansion) to leave them in place. Now if you needed space in that conduit for some reason...

-Jon

I'm with you now.

JAP>

 

[Smart $]

...
Rather than supplying all of the original 1,3,5,7 conductors from breaker 1, I would have supplied 1 and 7 from breaker 7...3 and 9 from breaker 9, and 5 and 11 from breaker 11.

This would free up the same number of breakers, keep loads distributed on the supply phases and on the field neutrals, keep the facility color code intact, and possibly save a wirenut

Great in theory but based on fact not yet in evidence, that being all things being equal load wise with former circuits 1 thru 11. However, they may not be equal and combining former circuits 1 thru 7 may be the best balancing of all loads now on 1, 9, and 11 (I do agree these could/should be 1,3,5 or 7,9,11 though). For example, original 1 thru 11 odd each had 12A when installed but over time 1 thru 7 were reduced to 3A each. The restructuring now has 12A each on A,B,C.










.

 

[david]

Is this what you guys are seeing

 

[jap]

Is this what you guys are seeing

Yes.
The 2 return neutrals just didn't seem right to me but I got over it.


JAP>

 

[jap]

Didn't like the fact that if you shut off circuit 1 it didn't actually kill all the return potential because there are 2 return neutrals instead of 1.

JAP>

 

[david]

Branch Circuit, Multiwire. A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.


How does this circuit meet the definition of multi wire branch circuit?

From my reading of the definition a multi wire branch circuit has only one neutral path connected to the grounded conductor of the system

Neutral # 1 and #7 would need to be spliced together to constitute a single grounded conductor connected to the neutral of the system

ether neutral path 1 or 7 would need to be eliminated for the circuit to meet the definition of a multiwire circuit

 

[GoldDigger]

If there are two neutral wires all the way back to the panel it is possible that it does not meet the MWBC definition. Anywhere down the line it is common to split an MWBC into single circuits or three wire MWBCs.

Sent from my XT1585 using Tapatalk

 

[david]

If there are two neutral wires all the way back to the panel it is possible that it does not meet the MWBC definition. Anywhere down the line it is common to split an MWBC into single circuits or three wire MWBCs.

Sent from my XT1585 using Tapatalk

Ok

 

[david]

And as it has been discussed here the circuit should be re-configured to be 7-9-11 multiwire circuit

Edit: Assumption, All this is being done in the cabinet for the pannel

 

[kwired]

I agree, if the field wiring was correct and compliant as 2 separate MWBCs (1,3,5 and 7,9,11) then there is no reason to change the field wiring in order to combine the circuits.

Rather than supplying all of the original 1,3,5,7 conductors from breaker 1, I would have supplied 1 and 7 from breaker 7...3 and 9 from breaker 9, and 5 and 11 from breaker 11.

This would free up the same number of breakers, keep loads distributed on the supply phases and on the field neutrals, keep the facility color code intact, and possibly save a wirenut

-Jon

Only thing wrong with OP is there needs to be a handle tie between the former 1,3,5,7 connection and the remaining 9, 11 connections. End result is one MWBC. If you ran four conductors of a "full boat" to a junction box right adjacent to the panelboard, and then split into the same 8 conductors to the outlets, electrically you still have the same thing.

 

[jap]

Is this what you guys are seeing

If you could, Please take this drawing , leave both neutrals in place in the field , but combine circuits 1&7, 3&9 and 5&11 on circuits 7,9 &11 with (2) return neutrals to the panels neutral bar and please repost.

I'm still not completely satisfied with this set up.

Something about having the (2) neutrals returning to the panel just doesn't seem right, even though the handle tie would kill any return on either neutral.

JAP>

 

[kwired]

If you could, Please take this drawing , leave both neutrals in place in the field , but combine circuits 1&7, 3&9 and 5&11 on circuits 7,9 &11 with (2) return neutrals to the panels neutral bar and please repost.

I'm still not completely satisfied with this set up.

Something about having the (2) neutrals returning to the panel just doesn't seem right, even though the handle tie would kill any return on either neutral.

JAP>

It isn't all that much different then running three hots and a neutral to a junction box, then splitting it into six hots and two neutrals. Somewhere in the circuit you have at least one neutral conductor carrying unbalanced current from more then one ungrounded conductor - you need common trip breaker or handle ties on the ungrounded conductors.

Even if this were a new enough install that the grouping of circuit conductors were required at installation - the hots would already be grouped with their corresponding neutral. All the conductors of the "new circuit" are not grouped together, but the neutrals are still grouped with the hot that will introduce current on the neutral - which IMO is the most important reason for the rule.

Before handle tie rule came out I sometimes did put MWBC's on non adjacent breakers - I made sure I got the ungrounded conductors on different lines but mostly did it when that was where open spaces were in the panels or wanted to disrupt as little as possible when adding new circuits (of course we all never worked in live panels, right?) But the handle tie rules and identification of the groups now will make panel changeouts or moving breakers around for whatever reason a little easier to get them back the way they were intended.

 

[jap]

It isn't all that much different then running three hots and a neutral to a junction box, then splitting it into six hots and two neutrals.

The difference is you only have 1 return neutral for the 3 circuits to the Panel's neutral bar from the 1st jbox in the scenario above,whereas in the OP's case they now have 2 neutrals returning to the neutral bar in the panel for only 3 circuits, but, i guess it doesnt matter,
Just odd in my opinion.

JAP>

 

[kwired]

The difference is you only have 1 return neutral for the 3 circuits to the Panel's neutral bar from the 1st jbox in the scenario above,whereas in the OP's case they now have 2 neutrals returning to the neutral bar in the panel for only 3 circuits, but, i guess it doesnt matter,
Just odd in my opinion.

JAP>

You still have sections of neutral conductor carrying imbalance current, somewhere it eventually splits off to two wire segments of the circuit. That can be in multiple locations on any MWBC.

Just so happens one split occurs at the panelboard enclosure in this case. Unless you can find anything in NEC prohibiting this, it is compliant.