Office Partitions and Art. 605.7

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johngil

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I don't frequently wire these freestanding partitions, but did note the code change for 2005 that requires a common disconnecting means for multiwire branch circuits feeding these partitions.
Typically, the whips contain 5 conductors. (3 hots, neutral and ground)
Some of the newer partitions have an 8 conductor whip which adds another hot, neutral and iso. ground.
I am being asked to supply UPS power to the separate set of conductors.
As I see it, the code will not allow this due to an inability to simultaneously disconnect all ungrounded conductors feeding the partition since they will be from separate panelboards.
Thoughts?

Before you get started,,, I do hate these things and they weren't at all my choice, but gotta pay the bills.
 
The way I read it you are still o.k.
The MWBC needs to have simultaneous disconnect, and then your UPS circuit will be seperate. I don't read where all four circuts have to be simultaneous.
 
What do you mean by a common disconnect? One breaker killing all the circuits? What happens when you have furniture partitions that are prewired and contain many circuits? I confused by the common disconnect means.

Sorry.
 
Agree, but isn't the intent to disconnect all ungrounded conductors for safety?

This was in a study guide I was reading through.


Change Significance:

These two types of equipment are often supplied with circuits from different panelboards. These circuits are present in the same junction box used to feed this partition furniture. The FPN at the end of Article 605 refers to 210.4 for circuits supplying partitions in 605.6 and 605.7, but this is really not an enforceable part of the Code article. Often, the architect or engineer calls for the installer to use specific circuits for the supply to the office partition, and these branch circuits may be from different panelboards.



Maintenance staff is not usually familiar with the source of circuits; when they get the trouble call for a problem with the partition furniture they often wind up getting hurt. Because these types of partitions are moved frequently, the electrician/contractor will be asked to disconnect and reconnect the furniture. Again, those individuals not familiar with the original install will get hurt. But by grouping the circuits together in the panelboard and by terminating the conductors on a multipole circuit breaker, this hazard may be reduced.



Multiwire branch circuits are not permitted to be used for individual or groups of interconnected individual office partitions. See 605.8(D).
 
I'll leave "intent" to someone who has a ROC or ROP. I was simply stating the way I think it reads. Since it doesn't mention "other circuits" one could 'assume' the intent might be the same as other MWBC restrictions, to prevent neutral "back-feeding".
My "intent" was to solve your (non)problem :)
 
I don't see what the owner is trying to do.. provide an emergency circuit for each cube? Even by putting the extra ckt on emerg wont give each systems furn. partition an emerg circuit. You couldn't put a handle tie on the breakers so I don't see how this would work.
 
How are you going to share the neutral with a UPS circuit and a neutral circuit?

Given that you only have one neutral to work with, I don't think you can do this and comply with the code.

Edit: My mistake, I now see the optional whip adds another neutral. As long as one neutral is dedicated to the UPS, and one for normal power, I agree with Augie.

Steve
 
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