Adding a sub panel

[Bojans]

I currently have a 200 amp service coming into the house on the far south end (farthest point from the garage possible). The electricians filled the main box (I believe a 50 slot) near capacity leaving only 2 open lugs. I am going to install a 100 amp sub panel this fall that will immediately be used to run a 220 to the garage for a compressor and an additional oven in the basement used when we are having large gatherings. In the future this panel will also be used when we finish part of the basement.

My question is on location. Should I put the sub panel right next to the main service? I was thinking if I put the sub panel in a more central location it would simplify my wiring and possibly save me some money on wire when I do finish the basement.

 

[royalton10]

Put your sub panel in the more central location. There are code considerations that others can detail. Not behind a door, etc.

The idea is to have the sub panel where it is convenient for you to work with. You have already picked up on that.

Upload some pictures on desired location and others can chime in about how it looks.

Good luck!!

 

[frankush]

How easy will it be to get a larger feeder to the new panel location? If you foresee that most of the new branch circuits will be in the basement, then that's probably the best place for it. The service panel is probably a 40 ckt. That's what they usually are. You're talking about adding some fairly large loads and it would probably be a good idea to put an amprobe on the incoming service feeds and check your current draw. It will probably be well below even 100 amps and will give you a little peace of mind.

 

[porcupine73]

It seems there is something in the code too that effectively limits the total number of branch circuits based on the size of the service.

 

[frankush]

Not unless it's in the most recent edition of the NEC. The code requires that the service size be adequate for the load based upon a load calculation.

 

[BigJohn20]

It seems there is something in the code too that effectively limits the total number of branch circuits based on the size of the service.

No, there's not (as per the NEC anyway). Depending on which code revision you're on, there used to be a limit to the number of circuits per panelboard (42) but that restriction was changed in recent revisions of the NEC.

 

[porcupine73]

Ah ok thanks, I think I was thinking of that 42 circuit per panel limit maybe, but I didn't realize that had been removed.

 

[Bojans]

Thanks guys. I have 2 locations I am considering, one is under the stairs that lead to the basement, the other is on the concrete wall very near to the garage. Both locations allow me to get conduit to and from the sub panel easily, the location under the stairs would be much closer to the area of the basement that will be actually finished.

Is it now code that you have the lights and outlets of a room on separate circuits? I have never seen this done before my house...

 

[mtne]

No, it's not code but rather common practice. With the earlier adoption of AFCI requirements if your house is recently built it may have been an attempt to avoid the nuisance tripping that was (and still in some cases) prevalent with arcfault / snap switch interactions. Otherwise, I've always been trained to try and keep your lighting and power circuits separate if doing the layout and it's within reason.