New Construction Garage and Mudroom Electrical ?

[Morrison]

Hello all -

Long time lurker first time poster...

We are having a mudroom and garage added to our house, should be starting in the next month or so. I have been planning on doing the electrical myself, I did home remodeling for about 8 years and have some experience running wires. Not so much in the planning side of things though.

I have a 200 amp panel in my house. There are two open spots in it. What I am debating between doing is

Options 1 - Can I just one slot for the mudroom and one for the garage? The mudroom will have one light inside, one on the porch and 4 outlets. The garage will have 4 lights inside, two outside the doors, 1 outside outlet and about 6 inside outlets.

I'm thinking of running 14-2 with a 15amp breaker for the mudroom and a 12-2 with a 20amp for the garage.

Option 2

Run a sub panel to the garage. 12-2 for the garage outlets, 12 - 2 for the mudroom outlets, 14-2 for lights in garage and another 14-2 for the lights in the mudroom.

I live in Rhode Island and my house is about 20 years old. The mudroom is 12x12 and the garage is 26 x 26.

Thanks for any help or advice!

 

[2ManyProjects]

Hello all -

Long time lurker first time poster...

We are having a mudroom and garage added to our house, should be starting in the next month or so.

Before getting into the gist of your question, a short side-trip:

What are you planning to use for heat in these spaces? And secondarily, what is the existing heating system for the rest of the house? Point is, NOW is the time to prepare for that, even if (you think) you aren't planning to install heat in the garage (or to not do so until "later"). Properly insulating the slab, and at least running the PEX tubing to accommodate future in-floor hydronic heat (even if that is ALL you do, initially) will pay HUGE dividends down the line. But if you go ahead and pour an uninsulated (or inadequately insulated) slab, without the tubes embedded, it become prohibitively expensive to retrofit later; and thus, you become forever "stuck" with some much less efficient, less comfortable, and more expensive to run "alternative" heating system.

OK. End of lecture (for now).

I have been planning on doing the electrical myself, I did home remodeling for about 8 years and have some experience running wires. Not so much in the planning side of things though.

I have a 200 amp panel in my house. There are two open spots in it.

That last sentence pretty much tells the tale.

What I am debating between doing is

Options 1 - Can I just one slot for the mudroom and one for the garage? The mudroom will have one light inside, one on the porch and 4 outlets. The garage will have 4 lights inside, two outside the doors, 1 outside outlet and about 6 inside outlets.

I'm thinking of running 14-2 with a 15amp breaker for the mudroom and a 12-2 with a 20amp for the garage.

Option 2

Run a sub panel to the garage. 12-2 for the garage outlets, 12 - 2 for the mudroom outlets, 14-2 for lights in garage and another 14-2 for the lights in the mudroom.

Go with Option #2, without question.

With only two open breaker slots in your main panel, you simply do not have adequate capacity to add all the circuits you WILL want/need in the mudroom & garage. (Sure, you MIGHT be able to squeeze out a couple more slots by going with tandem breakers for some of the existing 120V branch circuits; but that is a kludge, at best.) Adding a sub-panel opens up all sorts of possibilities, both for now and in the future.

Further, if this garage is destined to be anything more than a glorified car-parking facility, make that TWO 20A (12/2) circuits for the outlets, and TWO 15A (14/2) circuits for the lighting. We can discuss the details related to both of of those later, if desired.

I live in Rhode Island

All the more reason to NOT ignore the heating issue.

 

[Morrison]

We have a forced air furnace and the mudroom will tied into it but the garage is not going to be heated. I will work in it some in the summer but I have a 20 x 30 workshop in my basement. The foundation and floors have already been poured. 42'' footing, 8 inch floor in the garage, 2x6 construction. They're supposed to start framing in a week or so.

I was 99% certain that I was going to be installing a sub panel. I would assume if I was to install the receptacles on 12-2 (20amp each) and lights on 14-2 (15amp each) that I would need to bring in at least an 75 amp, maybe a 100 for future additions?

 

[2ManyProjects]

We have a forced air furnace and the mudroom will tied into it but the garage is not going to be heated.

I could give you all sorts of good reasons to change your mind on this, but...

The foundation and floors have already been poured. 42'' footing, 8 inch floor in the garage, 2x6 construction. They're supposed to start framing in a week or so.

That's too bad... And a very different situation from the impression you'd left earlier that construction was still a month or so away (which would have left time to make such changes). Oh, well.

I was 99% certain that I was going to be installing a sub panel. I would assume if I was to install the receptacles on 12-2 (20amp each) and lights on 14-2 (15amp each) that I would need to bring in at least an 75 amp, maybe a 100 for future additions?

Not necessarily. It all depends on what you plan to actually put in the garage in terms of electrical loads. There is no rule which states that the main feed needs to match (or exceed) the sum of the various branch-breaker ratings. In fact, it's fairly rare that it does. That said, both 60A and 90A are "popular" feed sizes, in part because they correspond to popular (and cost-effective) sizes/types of feeder cables. From the sound of it, you're not planning to get very "ambitious" in terms of power tools, machines, etc., in the garage.

 

[Morrison]

The foundation is done but the walls aren't going up for a few weeks. Guess my wording was poor.

The garage will mainly used for parking cars. I may being some machines home from work to fix but most of the stuff I work on is low voltage. No compressors or anything will be used.

 

[2ManyProjects]

The garage will mainly used for parking cars. I may being some machines home from work to fix but most of the stuff I work on is low voltage. No compressors or anything will be used.

In which case, 60A will likely be more than sufficient. This can be supplied via AWG 6 copper, or AWG 4 aluminum. If you want to go heavier/higher, you certainly can; but odds are you will never see the benefit (unless the sub-panel is more than perhaps 120 feet or so away from the main panel).

 

[Morrison]

Thanks for your input. The sub panel is about 30 ft from the main panel