New code requirement - phases sharing a neutral

[Stevareno]

I understand this requirement is for increased safety, but are there other factors that prompted this change?

Also, the code requires that the neutral be grouped with the phase wires they are associated with as they enter the panel. I didn't realize this at first and instead, I marked the neutral conductors with number markers indicating which circuits they pertained to.
After explaining to the inspector that what I did accomplishes the same thing as grouping, he let me get away with it "this time".
Why would the code not allow marking the neutrals in such a way?

I pride myself on making a panel not look like a rat's nest, and this grouping requirement makes things more complicated. How do you cope?

 

[ceb58]

I understand this requirement is for increased safety, but are there other factors that prompted this change?

Also, the code requires that the neutral be grouped with the phase wires they are associated with as they enter the panel. I didn't realize this at first and instead, I marked the neutral conductors with number markers indicating which circuits they pertained to.
After explaining to the inspector that what I did accomplishes the same thing as grouping, he let me get away with it "this time".
Why would the code not allow marking the neutrals in such a way?

I pride myself on making a panel not look like a rat's nest, and this grouping requirement makes things more complicated. How do you cope?

One can only assume you are talking about 210.4 (A) through (D) :?

 

[Dennis Alwon]

While the code says grouping you certainly accomplished what the code is looking for. Perhaps you can add that as a code change. The only problem I see if when someone moves a circuit around in the panel- it would be easy to not remember the remark the neutral.

Also depending on where the circuit is marked may also make it difficult to see the label on the neutral.

 

[hurk27]

The only problem I see if when someone moves a circuit around in the panel

I don't think this will happen much with 210.4(B) inplace?

Although I have been tempted to just reach up and kill the main if an inspector ever asked me if I have a disconnect for my multi-wire circuits.:ashamed:

 

[broadgage]

I believe that there is another reason for the code requirement that the neutral be grouped with the related phase conductors.

If the phase and neutral pass through different openings in a ferrous enclosure, such as a load center, then eddy currents will be induced in the metal which will become heated as a result.
In extreme cases this heating could damage the insulation, especialy of wires already loaded right to the limit.
This heating is unlikely to be significant with the modest currents involved in residential branch circuits, but of course the requirement also applies to heavy current work.

If the enclosure is non ferrous then it does not matter in practice, but is still a code requirement.
Likewise with DC it does not matter, but AC is almost universal these days.

 

[iwire]

Why would the code not allow marking the neutrals in such a way?

My guess is they want them to remain grouped regardless of the breaker numbering scheme. There are at least 3 ways I can think of to number a panel.

I pride myself on making a panel not look like a rat's nest, and this grouping requirement makes things more complicated. How do you cope?

I hardly think a tie wrap around each group as it exits the raceway is going to make your panel into a rats nest.

If you are as neat as you sound I am sure you will find a way to do it if you just accept it has to be done.

 

[George Stolz]

I hardly think a tie wrap around each group as it exits the raceway is going to make your panel into a rats nest.

If you are as neat as you sound I am sure you will find a way to do it if you just accept it has to be done.

Have you made up a panel under the new requirement? I can kinda see his point, but not to the point of complaining about it (no offense intended Stevareno). Just another one of those things I grumble about under my breath as I'm doing what's right.

 

[infinity]

IMO numbering each individual neutral is far better than a piece of tape around each MWBC group entering the panel in a common raceway.

 

[kwired]

I believe that there is another reason for the code requirement that the neutral be grouped with the related phase conductors.

If the phase and neutral pass through different openings in a ferrous enclosure, such as a load center, then eddy currents will be induced in the metal which will become heated as a result.
In extreme cases this heating could damage the insulation, especialy of wires already loaded right to the limit.
This heating is unlikely to be significant with the modest currents involved in residential branch circuits, but of course the requirement also applies to heavy current work.

If the enclosure is non ferrous then it does not matter in practice, but is still a code requirement.
Likewise with DC it does not matter, but AC is almost universal these days.

That problem was already addressed in other code sections, all conductors of the circuit already need to be in same raceway or cable, especially a ferrous raceway, and has nothing to do with identifying which neutral belongs to which MWBC.

 

[kwired]

I understand this requirement is for increased safety, but are there other factors that prompted this change?

Also, the code requires that the neutral be grouped with the phase wires they are associated with as they enter the panel. I didn't realize this at first and instead, I marked the neutral conductors with number markers indicating which circuits they pertained to.
After explaining to the inspector that what I did accomplishes the same thing as grouping, he let me get away with it "this time".
Why would the code not allow marking the neutrals in such a way?

I pride myself on making a panel not look like a rat's nest, and this grouping requirement makes things more complicated. How do you cope?

Unless you are just starting to use 2008 NEC this is not new.

You only would need to group circuits that come from raceways with multiple circuits installed in them. Otherwise a raceway or cable that only contains a single MWBC is already 'grouped' by its single entry into the panel.

 

[jaggedben]

I don't think this [moving circuits around in a panel] will happen much with 210.4(B) inplace?

It's true that if the previous electrician followed 210.4(B), then one can identify MWBCs relatively easily. But that makes it all the more true that if an electrician doesn't follow 210.4(B), they ought to group the MWBCs. I was just on an install where the panel was a mess of MWBCs that all were terminated, improperly, on single pole breakers. Fortunately the previous electrician had grouped the MWBCs with tape. Otherwise everything would have been a confounding mystery.

In solar installs we end up re-organizing panels a lot, either to make space for a solar breaker or to put it at the opposite end of the busbar per 705.12 (D)(7). We also often end up re-locating circuits to a new load center. It sure is less of a headache when the previous electrician has properly grouped the MWBCs. And obviously this doesn't just apply to solar, it applies to any addition of circuits.

IMO numbering each individual neutral is far better than a piece of tape around each MWBC group entering the panel in a common raceway.

I think numbering can be done in ways that makes the grouping clear, or can be done in ways that doesn't make the grouping clear. I'd go for numbering and grouping. It's hardly that much additional work.

 

[Stevareno]

I hardly think a tie wrap around each group as it exits the raceway is going to make your panel into a rats nest.

If you are as neat as you sound I am sure you will find a way to do it if you just accept it has to be done.

You are correct. I am sure that I will find a way to keep things in order with a little planning.

My main complaint is with the requirement that the MWBCs have to be simultaneously disconnected as per 210.4(B). In order to isolate a circuit for troubleshooting purposes, you can't just turn off a breaker any longer. You have to physically disconnect the wire from the multi-pole breaker.

I've heard other electricians complain about this. There's more work involved in having to take the panel cover off, etc. Some have stated that they plan on just running a neutral for each circuit to avoid having to use a multi-pole breaker.

 

[al hildenbrand]

My main complaint is with the requirement that the MWBCs have to be simultaneously disconnected as per 210.4(B). In order to isolate a circuit for troubleshooting purposes, you can't just turn off a breaker any longer. You have to physically disconnect the wire from the multi-pole breaker.

2011 NEC 210.4
(B) Disconnecting Means. Each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates.

Informational Note: See 240.15(B) for information on the use of single-pole circuit breakers as the disconnecting means.

So, looking at 240.15(B) we see:

2011 NEC 240.15
(B) Circuit Breaker as Overcurrent Device. Circuit breakers shall open all ungrounded conductors of the circuit both
manually and automatically unless otherwise permitted in 240.15(B)(1), (B)(2), (B)(3), and (B)(4).
(1) Multiwire Branch Circuits. Individual single-pole circuit breakers, with identified handle ties, shall be permitted as the protection for each ungrounded conductor of multiwire branch circuits that serve only single-phase line-toneutral loads.

I don't see any thing about having to remove the conductors from the breaker to accomplish the "simultaneous disconnect".

 

[kwired]

So, looking at 240.15(B) we see: I don't see any thing about having to remove the conductors from the breaker to accomplish the "simultaneous disconnect".

Reading between the lines a little bit, but I think he is complaining about having to turn off all ungrounded conductors instead of being able to use two or three single pole breakers without handle ties like we used to be able to do.

 

[al hildenbrand]

Reading between the lines a little bit, but I think he is complaining about having to turn off all ungrounded conductors instead of being able to use two or three single pole breakers without handle ties like we used to be able to do.

I'm not so sure. Look at my emphasis in red in the quote of Stevareno in my post above.

 

[al hildenbrand]

Reading between the lines a little bit, . .

OK. I get it now.

Some of the trouble shooting will benefit from having less than all of the MWBC conductors energized, and the premium priced common trip doesn't have a defeatable handle tie. :dunce:

 

[Stevareno]

Reading between the lines a little bit, but I think he is complaining about having to turn off all ungrounded conductors instead of being able to use two or three single pole breakers without handle ties like we used to be able to do.

Correct. For instance, on a service call in a working business, you isolate a problem and you need to turn that circuit off, but it's part of a MWBC. With this requirement if you turn off the breaker, you disconnect one or two other circuits unnecessarily, possibly interrupting someone working in that place of business.

I like to inconvenience the customer as little as possible.

 

[jaggedben]

Correct. For instance, on a service call in a working business, you isolate a problem and you need to turn that circuit off, but it's part of a MWBC. With this requirement if you turn off the breaker, you disconnect one or two other circuits unnecessarily, possibly interrupting someone working in that place of business.

I like to inconvenience the customer as little as possible.

Also, if the breaker trips due to a fault, you don't know which leg of the MWBC caused it to trip, and you can't find out unless you can disconnect one at a time, or you can remove the common trip.

What I'm a little unclear on is what would qualify as an 'identified handle tie' in 240.15, such that it would allow you to avoid this issue.

 

[ActionDave]

What I'm a little unclear on is what would qualify as an 'identified handle tie' in 240.15, ......

It has to come form a box marked "Handle Ties" not be a piece of #10 solid put in the holes of the breaker handles.

Some handle ties will not trip all the tied breakers on a fault but none of the identified handle ties will allow you to turn off only one breaker.