Wire Too Short for Sub

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  #1  
Old 07-21-19, 06:58 AM
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Wire Too Short for Sub

Planning to setup up a generator subpanel and need some guidance. I want to move the refrigerator circuit over to the sub but it is too short.

I traced the line coming into the main, the black powers the refrigerator, red powers the microwave. 2 separate breakers, one for frig one for mw.

1. Do I need to move the entire circuit red, black, white and ground into the sub? I only need the refrigerator not the microwave in the sub, but I can do both. If only one is moved, where is neutral and ground wired.
2. Can I run the lines through the side knockout on the main through the side knockout on the sub via conduit and then wirenut to lengthen?

Thanks
 
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  #2  
Old 07-21-19, 07:16 AM
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It is sounding as though you have a MWBC (Multi Wire Branch Circuit). If this is the case and you need to move one of the hots to the sub then both must be moved to the sub along with the neutral and ground. In the sub you would connect the two hots to the 2 pole breaker and connect your neutral to the neutral bar and the ground to the ground bar which should be separate from each other since it is a sub panel. The above applies only because of what you describe seems to reflect that of a MWBC. How is the circuit wired now to the main panel.

Are you using conduit to move the circuit to the sub for a particular reason. Either way, conduit or romex etc you can use a junction box in between the main and sub and make your splices there. Just be sure to use the same configuration off wire types such as if it is romex 12/3 on the circuit then you pull the 12/3 out of the main panel. Run it to a junction box, the continues on from the junction box with the same type such as 12./3 making your splices in the junction box and then continuing on to the sub panel making your connections as I described above.

Again, this is all predicated on the fact so far that what you describe is a MWBC. Presently the two hots should be connected to a 2 pole breaker or two single pole breakers above and below each other with a tie-bar between them so if one trips it will force the other one to trip.
 
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Old 07-21-19, 07:31 AM
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Ok, I understand. Here are pictures of the circuit, 11 is the refrig and 13 is the microwave. The sub is 6 inches away from the main.

I was going to simply going to unhook the 4 wires and run then through the side knockout of the main through conduit and then through the side knockout of the sub and wirenut there. But I believe the junction box may be cleaner.

When using a junction box, I understand that it needs to be exposed and needs to be the correct size for the number of wires in it. Can the junction be recessed as long as it has a plate on top that can be accessed?

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Last edited by PJmax; 07-21-19 at 07:40 PM. Reason: resized pictures
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Old 07-21-19, 10:00 AM
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If you are not in Canada you may splice inside the panel.
 
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Old 07-21-19, 05:04 PM
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When you say generator subpanel are you meaning gererator transfer panel?
 
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Old 07-21-19, 07:41 PM
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Can the junction be recessed as long as it has a plate on top that can be accessed?
Yes...... that is correct.
 
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Old 07-22-19, 05:57 AM
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Thanks all for the answers. I got a handle on it and how to proceed now. The generator panel is the following manual transfer switch.

https://www.homedepot.com/p/Square-D...DSGP/100096290.
 
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Old 07-22-19, 06:47 AM
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Still another question. This transfer switch panel allows for mini circuit breaker tandem style. Researching using these on a Multi Wire Branch Circuit says that it may not be a good idea on the same leg as it may overload the neutral. I called Schneider and they said they are approved.

I would have 2 MWBC's in this box, one for a set of lights and the other frig and microwave. Any concerns out there on using these?

Breaker link (https://www.schneider-electric.us/en...ka%2C-plug-in/)
 
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Old 07-22-19, 03:30 PM
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Yes, if in fact that this is a MWBC you do not want to connect this circuit to a tandem breaker or such the kind meaning a breaker that shares the same leg. The danger - it will overload the neutral. Google it for further explanation. Many people do not realize that you can overload a neutral and not just a hot.

The MWBC should be either a two pole breaker or two full size single pole breakers on two different legs tied together with a tie rod. Be sure that if you use two single pole breakers that you use an actual tie rod and not a piece of wire connected to the two single pole breakers as these fail many times.

I am not quite sure why Schneider would say that the tandem breaker is approved for a MWBC. Maybe the person you spoke too did not really understand what you were asking or they really did not know. The electrical theory of how a MWBC works and the construction of a tandem breaker would say it would not work. What ever type of breaker used to gain two circuits off of one leg is not safe.
 
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Old 07-22-19, 07:16 PM
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AFJES: THANK YOU SO MUCH... I would only be able to use 2 two pole breakers in this box because of space requirements and it will limit the total circuits I can use. So I plan now to go a different route based on attached diagram. But have another question.

Would I use a Main Lug load center? I was thinking of using this one: https://www.homedepot.com/p/Siemens-...125S/100096482 .

Diagram is missing main ground to separate ground bar in sub not bonded with neutral bar.
 
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Last edited by slynch401k; 07-22-19 at 07:34 PM.
  #11  
Old 07-23-19, 12:17 PM
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Thanks again everyone for all the help, I ordered this. It will be a week or so before it comes in but I appreciate everyone's input. I'm sure I will have more questions.

https://www.homedepot.com/p/Siemens-...25CU/203027242
 
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