New for the 2011 NEC Article 215.4 (A)... HELP!

[Breakermaster]

Hi everyone,

As I write this I can honestly say I have been stumped for the 1st time in my career. I teach continuing education for IEC Chesapeake. I had taken some time off. but back to education. As I was teaching a code change for 2011 using Mike's format, I came across this code section. 215.4 (A). It made no since to me. When I went over it in my class filled with 10 other MASTER ELECTRICIAN's no one could decifer what this code means or what it's intent. Between classes, I then referenced the code HANDBOOK to see what was behind this and it too does NOT give any incite. It appears that this is a new section since the 2008 NEC.

My question, can ANYONE let me and 10 other master electricians know what this means?

I have NEVER had multible feeders sharing 1 neutral! They are 2 or 3 wire feeders grouped with 1 multiwire neutral for each feeder, depending on if it is 3 phase or single phase. If I have more than 1 feeder, I have a multiwire neutral for each grouped feeder. What does this code mean and what is it trying to say? It mades NO since to me or any of my "students".

Thanks in advance for any help,

Scott Bowers

 

[infinity]

This was common in highrise apartment construction where the single common neutral is used to feed three panels. As long as the neutral is sized for the connected load there shouldn't be a problem.

 

[don_resqcapt19]

That code section is not new. It has been in the NEC for many code cycles.

 

[George Stolz]

200.4 is new, which requires one neutral for each multiwire branch circuit or feeder unless specifically permitted elsewhere in the code.

215.4 has examples of permission to do otherwise, and I believe 225.7 used to as well.

The idea is, if I can size one conductor to take care of the unbalanced load of several L-N circuits, such as an #8 neutral with multiple #12 ungrounded conductors, I could save money on wire.

I never had use for the design, myself.

 

[Dennis Alwon]

I believe the reason this is changed is because of article 210.4 which requires the breakers to be simultaneously disconnected when sharing a neutral. When you have multiple (more than 3 or 4) there is not available a means to simultaneously disconnect all the ungrounded conductors.

 

[George Stolz]

I can't handle tie five breakers together?

 

[Dennis Alwon]

I can't handle tie five breakers together?

I have not see a tie that was listed for more than 3

 

[George Stolz]

Care to prove or disprove that? I can tie handles all day in a QO panel, AFAIK.

 

[Dennis Alwon]

Care to prove or disprove that? I can tie handles all day in a QO panel, AFAIK.

I don't know about sq.D but AFAIK Ge cannot be done as you say nor can other brands I have used. Are your ties identified for the purpose as req. by 240.15(B)(1)

 

[bobbymari]

I have not see a tie that was listed for more than 3

come on now sure u have piece of #12 bare running through as many handles as u wish:lol: ive seen it on more than a few

 

[Dennis Alwon]

come on now sure u have piece of #12 bare running through as many handles as u wish:lol: ive seen it on more than a few

Yes, I have seen the nail on Sq. D but even then not more than 3. I think the nail is only listed for 3 breakers. The others brands don't have the holes as Sq. D does.

 

[don_resqcapt19]

I believe the reason this is changed is because of article 210.4 which requires the breakers to be simultaneously disconnected when sharing a neutral. When you have multiple (more than 3 or 4) there is not available a means to simultaneously disconnect all the ungrounded conductors.

210.4 does not apply to feeders.

The only reason for the change in Article 200 is because I wanted the CMP to comment on the issue of using a "common" neutral conductor. Prior to the 2011 code there was no code rule that said you could not use a common neutral. There were and still are two specific permissions to use one. The CMP had intended the specific permissions to act as a prohibition of the use of common neutral in other applications, but giving me permission to do something is not the same as telling me I can't do some other thing.

 

[Dennis Alwon]

210.4 does not apply to feeders.

No it doesn't 215.4 does and it allows up to 2 or 3 sets of feeders sharing a neutral. So why does the cmp allow this as clearly it can be as dangerous as a branch circuit sharing the neutral.