Breaking Neutral on a 120V branch circuit

[Nardie]

I have a design where a 120V branch circuit goes to a two-pole switch, then supplies power to several fire alarm equipment and a level indicator. The switch simultaneously breaks the hot and neutral when placed in the off position. From my quick reading of the code and based on my experience, it is not allowed to break the neutral. So I am asking obviously is breaking the neutral allowed per the NEC? Thanks

 

[LarryFine]

As long as all conductors are interrupted simultaneously, it's allowed.

 

[Nardie]

I appreciate the response, could you provide me the appropriate Code article that allows this. Like I said this is something I'm not used to. When, I look at article 300.13(B) this is not allowed. Also, article 210.4(B) only allows the simultaneous disconnecting of the ungrounded conductors not the grounded conductor (neutral). Thanks

 

[roger]

See 404.2(B) and the Exception.

Roger

 

[Nardie]

So I agree with the article reference and appreciate the response. However, if not needed why install a new installation to an exception if it can be done without applying it. Just a personal preference, I don't like installing new designs based on exceptions.

 

[ActionDave]

I think you are getting hung up on the term exception. There is nothing wrong or unsafe about breaking both conductors. Call it a perfectly legitimate, code permitted installation instead.

 

[Little Bill]

I appreciate the response, could you provide me the appropriate Code article that allows this. Like I said this is something I'm not used to. When, I look at article 300.13(B) this is not allowed. Also, article 210.4(B) only allows the simultaneous disconnecting of the ungrounded conductors not the grounded conductor (neutral). Thanks

Neither of the articles you mentioned has anything to do with your question of switching/disconnecting the neutral (grounded) conductor. Those articles are concerning MWBC. 300.18(B) is just saying that the neutral can't depend on a device for continuity in a MWBC, it must be pigtailed. This is for device removal. 210.4(B) is saying that the OCPD has to simultaneously disconnect all of the ungrounded conductors. This is for safety should you have to work on one of the circuits. Switching a neutral has nothing to do with these articles. But it is allowed, as has been mentioned and also the correct article. There are even some applications that require the neutral be switched or disconnected along with the ungrounded conductor. I don't see any problem with doing it in your application since it switches both grounded and ungrounded. An exception, unlike an informational note, is part of the code and can be used and in some cases, should be.

 

[Pipebender619]

I had a similar situation where we had to feed several in room ac units in a navy beq, and they shared the same circuit so we had to use two pole switches even though they were 120 units. Since there is the potential for shock from the neutral if another ac on the circuit is running. That is a perfect example of why you would switch the noodle.

 

[Ponchik]

I had a similar situation where we had to feed several in room ac units in a navy beq, and they shared the same circuit so we had to use two pole switches even though they were 120 units. Since there is the potential for shock from the neutral if another ac on the circuit is running. That is a perfect example of why you would switch the noodle.

What you are describing is a multiwire branch circuit. Two hots with a sharing neutral MUST have the hots disconnect at the same time. In a MWBC the neutral does not disconnect with the ungrounded conductors. The OP's installation disconnects ungrounded and grounded conductors at the same time.

 

[Little Bill]

What you are describing is a multiwire branch circuit. Two hots with a sharing neutral MUST have the hots disconnect at the same time. In a MWBC the neutral does not disconnect with the ungrounded conductors. The OP's installation disconnects ungrounded and grounded conductors at the same time.

I don't read pipebender619's post as being a MWBC. I think what he is saying is since all the units were on the same circuit and you had to work on one of the units, there would be a chance that the neutral would have current on it, backfeeding from the rest of the units. The same way you can get shocked working on a light with the switch off but other lights/loads are on and the neutral current is returning back on the light neutral.

 

[Nardie]

I think you are getting hung up on the term exception. There is nothing wrong or unsafe about breaking both conductors. Call it a perfectly legitimate, code permitted installation instead.

I disagree about my interpretation of exception. An exception is outside the general rule. In my opinion an exception should be utilized when the initial requirement can't be met or on special circumstances. I don't think we should design and install to exceptions unless it is required. I don't disagree about the allowance of the condition. It is just my opinion that when you install a new design to an exception instead of following the initial requirement you are circumventing the intent of the code. Again, this is just opinion.

 

[readydave8]

In my opinion an exception should be utilized when the initial requirement can't be met or on special circumstances.

In my opinion, most of the exceptions in the NEC are for instances where the initial requirement is unnecessary under the conditions mentioned