Double Pole 20 amp breakers on 120v MWBC

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Bill Davis

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McDonough, GA
As a favor to one of our GC's we are trying to finish a job for a competitor. This fellow was shipped the standard gear package from a national account. He has substituted 15 double pole 20 amp breakers for the 30-20 amp single pole breakers furnished for him. He said this is required when sharing neutrals. We have discovered he installed outlets and lighting from differing locations on these double pole breakers not sharing the same neutral. What is this fellow thinking?
 
The wording in the '08 has changed...

I do not see why he used 2 pole CBs though:
We have discovered he installed outlets and lighting from differing locations on these double pole breakers not sharing the same neutral.
Click to expand...
 
Here you go\
210.4 Multiwire Branch Circuits.

(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.
 
Shared neutrals or not a 2 pole CB is permitted to serve 2 single pole loads. On a three wire MWBC a 2 pole CB or two single poles with a handle tie is required.
 
120/240 1phase MWBC

120/240 1phase MWBC

What is the benifit of having an outlet in the floor being turned off at the same time as a lighting circuit in the back of the building?
 
Bill Davis said:
What is the benifit of having an outlet in the floor being turned off at the same time as a lighting circuit in the back of the building?
Click to expand...


None. So that brings us back to your original question, what is your question? :grin:
 
single phase 120/240 branch circuits

single phase 120/240 branch circuits

This store has been engineered to accomodate repairs with minimal down time. How is it that the code allows us to cause down time to cash wrap outlets to repair two rows of lights? If this is proper modification of the NEC I can not help but wonder, is anyone thinking?
 
infinity said:
The way I read it he already has the two poles so why not use them?
Click to expand...
[Not the way I read it...]


:-?

Bill Davis said:
This fellow was shipped the standard gear package from a national account.
He has substituted 15 double pole 20 amp breakers for the 30-20 amp single pole breakers furnished for him.
Click to expand...
He had the 2P 20A.
The package came with the CBs, so why change them?

Bill Davis said:
He said this is required when sharing neutrals.
Click to expand...
:confused:

It is NOT required....so why go through the time and expense?
 
Bill Davis said:
This store has been engineered to accomodate repairs with minimal down time. How is it that the code allows us to cause down time to cash wrap outlets to repair two rows of lights? If this is proper modification of the NEC I can not help but wonder, is anyone thinking?
Click to expand...


We are still trying to figure out if you truly have a MWBC. If you do then a dp is required.
 
OK, shared neutral (MWBC's) = 2 pole or handle tied single poles. Separate grounded conductor with each circuit use either 2 pole or single pole.
 
Missed the non-MWBC of the post, It's a stupid change for 08, but apparently not for the CMP. It will probably go the way of the non-removable breakers code change of many years ago. (I have only seen one panel like this, CH bolt in with tamper resistant screws holding the breakers to the buss)
 
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