Double Pole 20 amp breakers on 120v MWBC

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OK I am not there.

OK I am not there.

I have several crews in multiple states under my supevision. I am working off second hand information. I know because I trust the information given to me that there are no longer any single pole 20 amp breakers in these panels. I understand the 08 code requires handle ties on shared neutral circuits. I do not belive this new entry to the code is helping to create better installations,quite the opposite.
I red line every job I do before my guys leave the office. Sometimes I go for the slab rough and sometimes I go for the final. If I trust my guy I may not go at all. The biggest test I have is when I go on the final I check the load on the neutals one by one with all lighting on. This gives me a snap shot of the adherance to the red line drawings. If I find out some one intentionally evaded my instructions they don't go out again as a crew leader. All my fellow electricians agree that these drawings I prepare save them time and they save my company material.
The original question was, what is this guy thinking? I do not belive this fellow was thinking about how to best serve his customer, his town, his employees, his own safety or anyone elses. He somehow got hung up on a non-issue and tries to cover a lot of poor performance by throwing away 30 single pole breakers and installing 15 two pole breakers. Something that probably cost him $150.00 when the engineer would be responsible for making that change and aranging to pay him the difference. Again, what was this guy thinking?
 
Don't know what he was thinking but if he thought that the circuits would be sharing neutrals then he was correct. The 2008 NEC would require that all MWBC's be on mult-pole or handle-tied CB's.
 
Bill,

Now that you have invested time in gathering this info,
I suggest you do two things:

(1) Install the single pole OCPDs where appropriate,
and put the double pole CBs on the inventory shelf.

(2) Give your man credit for thinking about "What was this guy thinking?"
A 'thinking' employee may spend a minute extra thinking about the bigger picture,
but he is in line to do a better job and be more productive.

...
Thanks for the scenario and question.
I have not ever seen this type before.
...
 
What was Homer thinking when he bought Marge a bowling ball for her birthday?

I'd imagine the guy had a decent reason for doing a perfectly code legal thing. Practicality is always debatable.
 
Bill,

It's not the Engineers' job to lay out how an EC will run the circuits. If an EC decides to

use MWBCs' the EC should not expect the EE to pay for the handle ties.
 
Bill Davis said:
I have several crews in multiple states under my supevision. I am working off second hand information. I know because I trust the information given to me that there are no longer any single pole 20 amp breakers in these panels. I understand the 08 code requires handle ties on shared neutral circuits. I do not belive this new entry to the code is helping to create better installations,quite the opposite.
I red line every job I do before my guys leave the office. Sometimes I go for the slab rough and sometimes I go for the final. If I trust my guy I may not go at all. The biggest test I have is when I go on the final I check the load on the neutals one by one with all lighting on. This gives me a snap shot of the adherance to the red line drawings. If I find out some one intentionally evaded my instructions they don't go out again as a crew leader. All my fellow electricians agree that these drawings I prepare save them time and they save my company material.
The original question was, what is this guy thinking? I do not belive this fellow was thinking about how to best serve his customer, his town, his employees, his own safety or anyone elses. He somehow got hung up on a non-issue and tries to cover a lot of poor performance by throwing away 30 single pole breakers and installing 15 two pole breakers. Something that probably cost him $150.00 when the engineer would be responsible for making that change and aranging to pay him the difference. Again, what was this guy thinking?
Click to expand...

Not a lot.
The other guy, from what you posted, had no clue of what was or wasn't requried for mwbc or didn't understand what it was. Or he was not paying for the breakers, spent someone else's money for the dp breakers and used the sp's on a side job. You know higher profit margin:grin:
 
Thanks, y'all have been a great help to me. I did not want to add cost to an already messed up situation. I will for the moment have my man leave it as is and hope for the best on the C/O inspection Monday.
 
The installation is legal. It may prove a bit inconvenient for the circuits that do not share a neutral. That is because when the time comes to work on one circuit, it will take more out of service than is necessary. But that's the worst of it.
 
Bill Davis said:
He said this is required when sharing neutrals.
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As mentioned several times already, a DP breaker or approved handle tie is required.

Also, 300.13(B) requires that maintaining the continuity of the ungrounded/neutral conductors cannot depend on device connections (such as using a receptacle's screw terminals to land both incoming and outgoing conductors, or using one wire nut at a light fixture to tie the incoming, outgoing, and fixture neutral together) where disconnecting the device breaks the continuity of the neutral. Using pigtails is required.

We have discovered he installed outlets and lighting from differing locations on these double pole breakers not sharing the same neutral.
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This kindof threw me for a little while, I interpreted it as meaning you found that they share a neutral with another circuit, but not with the other leg of the 2P breaker.

Not sharing the same neutral is legal because you don't have to share the neutral but if there's sharing involved, it must be with the other leg of the 2P breaker only.

kent
 
KentAT said:
Also, 300.13(B) requires that maintaining the continuity of the ungrounded/neutral conductors cannot depend on device connections (such as using a receptacle's screw terminals to land both incoming and outgoing conductors, or using one wire nut at a light fixture to tie the incoming, outgoing, and fixture neutral together) where disconnecting the device breaks the continuity of the neutral. Using pigtails is required.




kent
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Kent that seems to be a misinterpretation of 300.13(B). The wire nut is not a device.
 
Hmmm, I didn't look at it that way - I guess it is my interpretation. I'm not thinking of the wirenut as a device, but rather I see the fixture as the device, and the single neutral wirenut (what I consider the device connection if there is no pigtail) as a device connection. Removing this wirenut to disconnect the device breaks the continuity of the shared neutral.
 
KentAT said:
I'm not thinking of the wirenut as a device, but rather I see the fixture as the device, and the single neutral wirenut (what I consider the device connection if there is no pigtail) as a device connection. Removing this wirenut to disconnect the device breaks the continuity of the shared neutral.
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I do not see a fixture as a "device":

2008 NEC said:
Device.
A unit of an electrical system that carries or controls electric energy as its principal function.

Luminaire.
A complete lighting unit consisting of a light source such as a lamp or
lamps, together with the parts designed to position the light source and connect it to the power supply. It may also include parts to protect the light source or the ballast or to distribute the light. A lampholder itself is not a luminaire.
Click to expand...

A luminaire does not "carry or control", but rather "utilizes":
2008 NEC said:
Utilization Equipment.
Equipment that utilizes electric energy for electronic, electromechanical, chemical, heating, lighting, or similar purposes.
Click to expand...

JMSO :smile:
 
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