# Siemens Sub Panel Wiring



## rrolleston (Oct 17, 2011)

Easiest way would be with 1/0 SER 4 wire cable because you are required to run 4 wires and also you will have to put that 100 amp breaker in a spot that has a smaller breaker a across from it because those panels are limited to 100 amps per stab on the bus.

You can't run separate wires without conduit and there has to be four conductors.


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## k_buz (Mar 22, 2012)

drunkboating said:


> I was doing research online and figured a post here would be helpful.
> 
> We need to wire in a sub panel for a basement project. The new expansion will support 4 new circuits and an oven.
> 
> ...


You cannot use the 3 conductor SE cable to feed the new subpanel. It must be 4 wire (2 hots, neutral, and ground), pipe between the panels in metal conduit and run 3 individual conductors, or pipe PVC between panels and run 4 individual conductors (2 hots, neutral, and ground). 

In all of these cases the neutral must be insulated and sized the same as the hot conductors. The only conductor you can downsize is the ground.


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## k_buz (Mar 22, 2012)

rrolleston said:


> Easiest way would be with 1/0 SER 4 wire cable because you are required to run 4 wires and also you will have to put that 100 amp breaker in a spot that has a smaller breaker a across from it because those panels are limited to 100 amps per stab on the bus.
> 
> You can't run separate wires without conduit and there has to be four conductors.


1/0 is overkill the max you would need is #1, maybe #2 depending on the type of wire contained in the cable.

You are not required to run 4 wires by the NEC. I've seen this stated numerous times here and its simply not true. You are required to have a ground present, but you do not need to pull a ground if the panels are connected by EMT or RMC.

If there is a 100A breaker installed, you cannot have any breakers on the same stab.


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## rrolleston (Oct 17, 2011)

k_buz said:


> 1/0 is overkill the max you would need is #1, maybe #2 depending on the type of wire contained in the cable.
> 
> You are not required to run 4 wires by the NEC. I've seen this stated numerous times here and its simply not true. You are required to have a ground present, but you do not need to pull a ground if the panels are connected by EMT or RMC.
> 
> If there is a 100A breaker installed, you cannot have any breakers on the same stab.


1/0 SER is what I would use if the person don't want to pay for conduit to be fitted between the two panels. It's only about $1.75 a foot

I doubt he is going to be cutting or bending EMT or RMC.

You can have another breaker on the same stab as the 100 amp breaker as long as the calculated load is under 110 amps. 15 amp breakers across from it should be fine.


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## k_buz (Mar 22, 2012)

> 1/0 SER is what I would use if the person don't want to pay for conduit to be fitted between the two panels. It's only about $1.75 a foot


It may be what you would install, but its not required. Why tell someone to get something 2 sizes larger than what is required?



> I doubt he is going to be cutting or bending EMT or RMC.


But you don't know that. The panels could be right next to each other and a EMT nipple might be even easier than SER. I don't see how it is a good idea to tell someone something is required when it isn't.



> You can have another breaker on the same stab as the 100 amp breaker as long as the calculated load is under 110 amps. 15 amp breakers across from it should be fine.


I disagree. While there might not be 100A on the stab when he first installs the breaker, what's to say its not going to be loaded to 100A in the future? I think you have to look at it as the total possible loads on that stab. I believe this is manufacturer specifications so I don't think we will find anything in the NEC on this subject. We could just agree to disagree on this one.


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## drunkboating (Apr 4, 2012)

The panels will be installed right next to each other. If a section of EMT will be conducive enough to keep from having to wire in yet another connection I'm all for it. Ultimately I'm not trying to over engineer it, just keep my kids safe.


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## k_buz (Mar 22, 2012)

I would get a short 1 1/2" or 2" EMT nipple, 2 EMT connectors, 2 plastic bushings, and run 3 conductors...2 hots and 1 insulated neutral (tape the neutral with white electrical tape). The ground would be carried by the nipple. Then you don't have to get an additional lug to fit the ground to the ground bar.

Be sure to remove the boding jumper going from the neutral bar to the back of the sub panel.


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## oleguy74 (Aug 23, 2010)

just run a #8 green for ground.all you need and it will fit the buss.


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## HouseHelper (Mar 20, 2007)

The #2Al is too small for the 100A breaker. Either use a 90A breaker or upsize the wire to #1Al or #3Cu. For that short a distance, I'd use Cu.


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