Subpanel in attached garage.

[keating]

I've just purchased a new home, taking possession on Sept 21st, and one of my first projects will be running a sub to the attached garage.

The Main panel is in the basement, fed from an underground service entrance.
It's a 200A GE PowerMark Gold, 32 Space - 40 Circuit. with about 14 spaces currently in use (mostly 15 amp lighting & outlets, 2x 20A to kitchen counter outlets and a couple double pole for AC, clothes drier and an unused range plug, since we have a gas range)
It's the panel with the Main Breaker that looks like 2 double pole breakers with a tie bar.
Looks like this guy:

I will install a 15A double pole for the compressor which will live in the basement next to the panel and be plumbed to the garage, and a 80A double pole to feed a subpanel in the garage

So to get to my garage, I have a straight shot about 12' across the (unfinished) basement ceiling, through the rim joist into the garage and straight up about 5' to where I want to locate the sub panel.
Including feeding around to the main disconnect, etc, looking at a maximum 20' run.

I want everything in the garage in conduit. So my understanding is that because I can't run NM in conduit, and I can't run individual conductors exposed, I will need to run conduit from the main panel all the way to the sub, in order to run individual conductors. Correct?
Due to the complexity of curves to get out of the main panel and across the ceiling in the basement, I'm considering flexible conduit from the main panel, then convert to ridgid (EMT or PVC) with a 90 degree fitting where I enter the garage at the rim joist.

I intend to install a 80A breaker in the main panel with four (3x 4AWG / 1x 8AWG ground) individual conductors feeding a main disconnect subpanel.

Since it's an attached garage, I do not need additional ground rods. Just 2 hots to their respective buss bars, Neutral to the neutral buss bar, ground to the ground buss and remove the bonding screw.

Anything important I'm missing here?

Thanks in advance.

 

[oleguy]

you need #4 for 80 amps.#6 is good for 65 amps.#8 is good for ground.

 

[keating]

you need #4 for 80 amps.#6 is good for 65 amps.#8 is good for ground.

You're right. I'll go back and edit that.

 

[tfi racing]

Where are you going to find an 80A breaker for that oddball GE panel?(not too popular out here at least) Don't waste your time and money with 80A and EMT conduit(PVC not permitted in your case) with individual conductors(#4 cu not the easiest to find either,expect to pay extra for special order),a lot more effort and expense for absolutely no advantage.#2/3 NMD90 or ACWU cable on a 100A breaker is the way to go on this side of the border.Also keep this in mind,our American friends on this forum mean well with their tips,but our code is different and a lot of the product and some of their methods they use are just not legal,popular or available up here.

 

[pattenp]

Very good point. That's why it's always good to show your location when asking these kinds of questions.

Where are you going to find an 80A breaker for that oddball GE panel?(not too popular out here at least) Don't waste your time and money with 80A and EMT conduit(PVC not permitted in your case) with individual conductors(#4 cu not the easiest to find either,expect to pay extra for special order),a lot more effort and expense for absolutely no advantage.#2/3 NMD90 or ACWU cable on a 100A breaker is the way to go on this side of the border.Also keep this in mind,our American friends on this forum mean well with their tips,but our code is different and a lot of the product and some of their methods they use are just not legal,popular or available up here.

 

[keating]

Where are you going to find an 80A breaker for that oddball GE panel?(not too popular out here at least)

Pretty common around here. Seems Minto installed them in every house they built around here in the early 2000's...At least every one with a 200A service, which, granted, isn't a lot. Breakers are easier to find and half the price of the bolt-on breakers for my Cutler-Hammer Commander (QM/QL) panel in my current place.

Don't waste your time and money with 80A and EMT conduit(PVC not permitted in your case)

Oh really? what about branch circuits? I've got the yellow book (summary) packed up somewhere. Don't have it handy, but I'll refer to it before buying anything.

with individual conductors(#4 cu not the easiest to find either,expect to pay extra for special order),a lot more effort and expense for absolutely no advantage.#2/3 NMD90 or ACWU cable on a 100A breaker is the way to go on this side of the border.

Fsck. Maybe I'll just **** it up and stick with 60A then.
I'd intended to go with 60A, since the compressor is staying in the basement and not on the sub. I mentioned it when going through the house with the home inspector and he said "you got the space, you got the capacity, why not go 80?".
I've got a Lincoln 175ST and an old Mastercraft 225A AC buzz box, plus I want several 20A circuits around the perimeter of the garage for power tools, like my chop saw that trips the 15A breaker whenever it's working hard.
Genreally, I'm the only one working in the garage, so 80A would be overkill. 100A would be crazy.
I can stick with 60A and use a more common breaker and #6/3 NMD-90.
My sub will be Square-D / Siemens as they are the most common and by far, the cheapest breakers available locally.

Also keep this in mind,our American friends on this forum mean well with their tips,but our code is different and a lot of the product and some of their methods they use are just not legal,popular or available up here.

Absolutely. I appreciate the input, and the Canadian perspective.

 

[jvitez]

Add up the wattage, not amperage, of everything you could possibly have running at the same time: welder, compressor, light, electric heat, radio, toaster, beer fridge, etc. 60 amps x 240 volts = 14,400 watts. That's quite a bit of power unless you're planning on a lot of electric heat.

 

[Norcal]

A 70A breaker should be easy to source, & a bit cheaper then a 80A, 80, 90,& 100A cost the same, just be sure to use a GE (Government Electric, Good Enough) breaker.


For a small 1-man shop 60A will be adequate, as how many machines can 1 person use at 1 time? A 60A breaker is cheap too.

 

[keating]

Add up the wattage, not amperage, of everything you could possibly have running at the same time: welder, compressor, light, electric heat, radio, toaster, beer fridge, etc. 60 amps x 240 volts = 14,400 watts. That's quite a bit of power unless you're planning on a lot of electric heat.

Planning on a basic 240v/4800W shop heater.

unless I can find a decent, cheap forced air / hot water unit I can plumb into the boiler that runs my in-floor heating in the house.

And 6-8x double tube 48" T8 fixtures. (<500W)

the biggest draws will be the welders.....only one running at a time....probably never run the 230A buzzbox at full power, and if I did, the doors would be open, so the shop heater wouldn't be running. I think 60A will be plenty.