Running subpanel to attached Garage

[jimmyfloyd]

ok, looking for a little help on this. I have an attached garage I would like to put a subpanel in, and re-wire all items there to it. I have this panel already:

http://www.homedepot.com/p/GE-Power...ug-Circuit-Breaker-Panel-TLM812RCUP/202046230

The circuits I plan to have are as follows:

Space - Item
1&2 - 220V Pool Pump Motor
3&4 - 220V 5hp/20gal craftsman Air Compressor
5 - 15 amp Double Pole breaker - a) Indoor Lights, b) exterior lights
6 - 20 amp Double Breaker - a) Garage Fridge, b) Door Opener
7 - 20 amp general outlet circuit 1
8 - 20 amp general outlet circuit 2

Due to shelving/built-in/vehicle placement, I really only have one available spot for this near the front of the garage. This location is next to the man door, on the latch side (no swing issues) and even with a car parked there, there will still be ample working space.

Now, there are 2 issues with this placement: 1) Distance from the main Panel, 2) distance from the majority of the loads.

Now, for the first one, the Main panel is at the center of the back basement wall, and the subpanel location is at the front, house wall of the garage, 12 inches forward of the front wall of the house since the garage is 5-6 feet forward of the house. I know I can run the wires in the basement just fine, but it is the location that I need to have the wiring come out that may be an issue. I have a hose connection that is right next to where I would like to bring the electric, in conduit, out of the house, then up and over to the panel. Will this be an issue for code, and is there a distance requirement between wiring and plumbing in this respect?

The second issue is that the panel would be located at the front right corner of the 22x24' garage (when looking in from garage door) and most of the equipment will be located along the back wall, with the pool pump and compressor being in the back left corner, exactly opposite the panel. I know this one isn't really that big of a code issue, but more of a cost/space issue. With this, would it be wiser to run individual romex circuits following the roof line, or a single large conduit over the center, then breaking out the circuits with one of those large, square junction boxes?

Unfortunately, the placing the panel near the pool pump, which would be ideal, would be blocked by my lawn tractor in the summer, and my car in the winter while being stored.

 

[wyliesdiesels]

Why are you using an outdoor 3R rated panel?

Could use an indoor...

No code issue with regards to plumbing and wiring distances.

How long is the run from the main to the sub?

 

[ard]

I typically wouldn't be concerned with a tractor, mower or car in front of a sub panel....

Not saying it isnt a code issue, but what I park after the inspection is done is my business.

I go years between 'panel visits' ....

 

[jimmyfloyd]

Why are you using an outdoor 3R rated panel?

Could use an indoor...

No code issue with regards to plumbing and wiring distances.

How long is the run from the main to the sub?

Got it on clearance a while ago and have it on hand is the reasoning. I have an indoor one too, but figured since there was a chance an errant hose could splash it, the outdoor was a better choice.

The indoor run from panel will be roughly 35-45 feet in the basement, then 6-8 feet in the garage.

 

[wyliesdiesels]

aww ok.

That distance shouldnt be an issue though you havent disclosed what size wire or breaker you will be using.

As to bundling romex in conduit, u cant do that past 24" without derating it.

And if u run multiple individual conductors in conduit they will have to be derated as well.

Not worth running all in the same conduit unless u want to spend extra time calculating derating factors....and possibly extra money on larger wire...

 

[jimmyfloyd]

For the breaker, I was thinking 100 amp, just to future-proof it size wise. For wire size, I would guess #3 or #4 cu would work for this.

Thanks for the comment about derating the wires. I think I would prefer to use romex and then just use conduit for protection out of the panel up to the ceiling height.

 

[wyliesdiesels]

#3 cu would be minimum for 100a. But that will be pricey compared to aluminum as you will need 3 lengths of #3 cu and 1 length of #8 cu....

BUT do you really need 100a? I doubt it.

Is this a one main garage?

Are you running this feeder from the main to the sub in conduit? Will it be subject to damage?

If the answer is no to both, then i would suggest #2 AL SER on a 90a breaker as a cost effective alternative...

Dont forget a separate ground bar for the sub as well as to isolate the neutral bar...

 

[anuccite]

#3 cu would be minimum for 100a. But that will be pricey compared to aluminum as you will need 3 lengths of #3 cu and 1 length of #8 cu....

BUT do you really need 100a? I doubt it.

Is this a one main garage?

Are you running this feeder from the main to the sub in conduit? Will it be subject to damage?

If the answer is no to both, then i would suggest #2 AL SER on a 90a breaker as a cost effective alternative...

Dont forget a separate ground bar for the sub as well as to isolate the neutral bar...

As Wylie says.... feeding it with 90amp should be enough for MOST of your average home owner / tinkerer type people....

EDIT: Scratch this as you have a main lug in an attached garage. "You can obviously have whatever size main breaker in the panel in the garage "

I struggled with this same question for a while when deciding what to do, and was convinced 90amp would more than cover my needs, even after adding AC, fridges, welder, etc.... the chance that everything i own draws peak amperage at the same time is almost nill

 

[jimmyfloyd]

I actually probably don't need 100 amps. Probably won't need 90 amps either. For interior lighting, I have:
4x - 2'x4' 2 bulb T8 Troffer lights,
2x - 60 watt bulbs,
may add 2 more troffers

For exterior, I have:
1x - Pole light with 3 40 watt bulbs
2x - dual 90 watt flood lights
2x - 60 watt individual fixtures
1x - 100 watt Low voltage transformer.

The pool pump is 3/4 hp 110V currently, but want to switch to 220V

The air compressor is currently a 2hp, 12 gallon, 110V, but I have a 20 gallon, 220V compressor that I'll be swapping the compressor unit from the first onto. I may also use this plug for a welder in the future.

Other than that, I have basic Craftsman power tools (10" table saw, benchtop drill press, circ saw, etc) and the Fridge, which is a newer, energy star rated standard size unit.

The only other addition may be a hot tub, but that could be run to it's own setup, as we will need to upgrade the main panel to support it.

So it seems like I could probably get by with a lower amperage, and it sounds like 90amp would allow for smaller wire size than 100 amp.

Thanks for the information so far. It's been helpful for my planning. I am going to try and get a picture of the location the panel will go later to get input on how to run the wire to it, as I have a couple questions on that.