subpanel

[HockeyFan]

I'm building a concrete house and in the garage, I'm hoping to provide for a future when that might be converted to a couple of bedrooms. I'm already putting a small bathroom with shower in it. For electrical, I was thinking about putting a subpanel in there, and then homing one or more circuits from that panel. Is that overkill? Should the garage just be one circuit and forget about the subpanel?

If I do put in a subpanel, what size of wire should I run from the main breakerbox?
If I don't put in a subpanel, will the circuit in the garage just be 12/2 or since I might be operating some drill or saw, should I be using something for a bigger current?

Since we could be putting in a couple of bedrooms, I was thinking the subpanel would be the way to go. It's easier to put it in now, than to deal with it later.

[HockeyFan]

As a follow-up to my original question, I'm thinking that the sub-panel should be sized for 40amps with a 8/3 feeder from the main breaker box. The circuits from the sub-panel would be 20amp circuits using 12/2. Does that seem right?

What size of conduit for under the slab does the 8/3 feeder need to be in?

[jwelectric]

I'm building a concrete house and in the garage, I'm hoping to provide for a future when that might be converted to a couple of bedrooms.

Is this garage attached or detached?

I'm already putting a small bathroom with shower in it. For electrical, I was thinking about putting a subpanel in there, and then homing one or more circuits from that panel. Is that overkill? Should the garage just be one circuit and forget about the subpanel?

The bathroom will require a 20 amp circuit for the receptacle that is installed for the sink. The lights in that bathroom can be wired off this same circuit but nothing else such as the light in the garage. It would be a lot easier to install a circuit for the bath receptacle and another for the bath and garage lights as long as the garage is attached. If the garage is detached then a subpanel will be required to be installed and the panel will be required to be rated as service equipment.

If I do put in a subpanel, what size of wire should I run from the main breakerbox?
If I don't put in a subpanel, will the circuit in the garage just be 12/2 or since I might be operating some drill or saw, should I be using something for a bigger current?

The size of the panel will not matter as long as it is not smaller than the feeders and the overcurrent device installed to protect the feeders. If this garage is detached and is going to have more than two circuits then the feeders and the overcurrent for the feeders can not be smaller than 60 amps.

Since we could be putting in a couple of bedrooms, I was thinking the subpanel would be the way to go. It's easier to put it in now, than to deal with it later.

Getting from the subpanel to the devices in a concrete building will be a chore no matter what you decide.

As a follow-up to my original question, I'm thinking that the sub-panel should be sized for 40amps with a 8/3 feeder from the main breaker box. The circuits from the sub-panel would be 20amp circuits using 12/2. Does that seem right?
What size of conduit for under the slab does the 8/3 feeder need to be in?

If you are planning on installing pipe from panel to panel then do yourself a favor and don’t install any type of cable but install single conductors instead. Remember the feeders must be sized no smaller than the calculated load to be served and if the garage is detached then a whole different can of worms is opened.

[HockeyFan]

Attached.
The garage is attached.

[jwelectric]

Then you have a choice between the panel and circuits.

[HockeyFan]

I think just for future considerations, I'll go ahead and put in a sub-panel. That way if there's remodeling and we convert it over to bedrooms, I'll already have a sub-panel there to add to. I'm figuring a 60amp sub-panel should be fine.