subpanel off a 20amp circuit?

[davidfite1978]

I'm not sure if there is even any benefit to this or not, but just wanted to run it by you guys....

I have a shop that is (who knows.... 100ft?) from the house/main panel. It currently has 1 - 20amp circuit running to it. Eventually I want to run a new circuit/cable so I can have a proper sub-panel and enough juice to do whatever I want.

In the meantime, would it help/hurt if I go ahead and put a subpanel in and start using it? I'd get a 100amp panel so it's sized for what I want down the road. I'm sure I won't use anything more than lights and 1 tool at a time for now. My thought is that it'd be fine, just sounds weird and is probably overkill for what I need it for. I just hate to start connecting a ton of receptacles and lights to 1 circuit and then have to re-wire because I didn't run them all to separate circuits in the first place.

Hopefully that makes sense.

 

[The Cobbler]

is the 20 amp 120v or 240 v?

 

[Norcal]

The main lugs of the panel most likely will be too large for 12 AWG.

 

[theoldwizard1]

In the meantime, would it help/hurt if I go ahead and put a subpanel in and start using it? I'd get a 100amp panel so it's sized for what I want down the road.

The main lugs of the panel most likely will be too large for 12 AWG.

Other than the lug problem, no issue. Get a "main lug" load center and install whatever size main breaker you want. Just don't up size the breaker in the house until you up size the wire.

 

[justsam]

If initially it will be energized with only 120VAC, you will need to use every other breaker position, (depending on panel).

If ultimately you will have no more than six circuits in the subpanel you will not need a main breaker at the subpanel. You can back feed via one breaker position, and will not have a lug size issue.

 

[Zeke]

If you leave yourself enough wire in the new panel you can change it at will. You can establish separate circuits now as well. If you overload, you will trip the feed, that's all. But, if you do put this new sub panel in ahead of a larger feed, do the required ground rod and isolated neutral bus as you would if you were doing the whole job. No more than 6 circuits until you put in a main breaker to serve as a disconnect (never a bad idea anyway).

Just curious, do you have 2 ungrounded conductors, e.g., a hot and neutral, plus a ground in the form of a wire coming in now? Otherwise, you aren't starting out with much and I'd wait and do the whole job.

 

[davidfite1978]

is the 20 amp 120v or 240 v?

120

Just curious, do you have 2 ungrounded conductors, e.g., a hot and neutral, plus a ground in the form of a wire coming in now? Otherwise, you aren't starting out with much and I'd wait and do the whole job.

Not at home but if I remember correctly I have 3 wires (hot, neutral, and ground). It's the underground cable type, going from 20amp breaker in the house out to the shop into a regular receptacle, and then on to lights and other receptacles from there. There's no grounding rod or anything like that yet.