Electrial service to my new garage

econoline · 11-21-2007, 10:04 AM

Gents, I'm glad to have found this site. I just built me a 3 bay garage.Now I need to power it up.
In my younger days I worked part time as an electrians helper (many noons ago). I thought I new the size wire I needed till I read the post on the 350 ft. supply run to the boat dock.
If someone would be so kind to help me spec my materials for this project.

It starts at my utility room "landlord" panel...150 amp main, ocupied by 4 / 15amp breakers (2 for common lighting, 2 for natural gas boilers). This is where I would like to feed out of with a 100 amp breaker.

110ft run thru 1.5 in. schedule 40 buried 2.5 ft. deep.

At the garage, should I use a main lug panel?? or I prefer a main breaker if that is acceptable.

I seem to remember about a sub-panel bonding screw or ????

The garage panel is considered a sub-panel ??? so I need 4 wires to it ???, using the house ground???.....I was thinking 2-2-2-4 ______????? (110 ft.)

power needed....Lift 12amps @ 220.....compresser 14amps @220
2 GDO's.....furnace / boiler......lighting...outlets for power tools....

Any thoughts would be greatly appricated...workin off extension cords, on a creeper, in a dimmly lit and cold, but brand new garage....Al

NateHanson · 11-21-2007, 11:37 AM

It's best to run 4 conductors (HHNG), and remove the bonding screw in the sub-panel, so neutral is separate from ground all the way back to the main panel.

You can have a main in the subpanel.

You'll need a grounding rod near the subpanel, unless the garage is attached to the building that houses the main panel.

RichyL · 11-21-2007, 12:12 PM

110ft run thru 1.5 in. schedule 40 buried 2.5 ft. deep.

The garage panel is considered a sub-panel ??? so I need 4 wires to it ???, using the house ground???.....I was thinking 2-2-2-4 ______????? (110 ft.)

If your running it in conduit you wanna use THWN i 3 number 2's and a number 4 ground, I dont think voltage drop will affect you too much here.
Make sure you get permission from your landlord, although I'm pretty sure you probably already have.

Stubbie · 11-21-2007, 01:50 PM

What equipment in that garage is going to require a feed of that amperage? I'm not saying you shouldn't run 100 amps but this is a heck of a load for a garage. Look at it this way... your service is 150 amps if based on equipment that is running at the same time in the garage and you truly needed a 100 amp feed to cover the demand out there you would only have somewhere in the neighborhood of 60 amps available for the house. So IMO there are a couple ways to look at this....
1.) I don't need 100 amps but 60 amps should cover everything so run a 60 amp feed to a 100 amp sub-panel in the garage.....I can always pull in a 100 amp feeder if I ever need it.
2.) I don't need 100 amps but I might someday so I'll go ahead and run 100 amp conductors and protect them with a smaller than 100 amp breaker probably a 60 amp.

The whole idea here is to keep the garage from demanding too much load from what is required at the house causing the main 150 amp breaker to trip out. Also wire isn't cheap and the figures given by the others is for copper wire. If you want 100 amps I would run an aluminum feeder to the garage. 60 amps I would run copper.

Just my thoughts

Stubbie

econoline · 11-22-2007, 04:50 AM

Thanks for all the great feedback but I guess I kinda expected that everyone knew what a "landlord panel" was....with that said....
I own a 2 family house. Myself and the tenant each have our own meters and panels...

The "landlord panel" is a third meter and panel so the common electrical expenses (ie; power for outside lighting and the heating systems) will be incurred by the landlord and not eighter tenant. The 150 amp panel ONLY feeds 2 natural gas boilers and 2 lighting circuts with a couple of motion sensor floods. As you can see 150 amps is way over kill for 4 15amp circuts.

With the power requirements given in my first post, do you think a 60 amp sub is enough...
(you're right, that wire is VERY expensive)
so I want to do it right....not overkill as I'm known for..............

Andy in ATL · 11-22-2007, 05:07 AM

60A is plenty IF you will be the only one working out there. Where the problem can come in is if you have your wife and kids out there running power tools all at the same time.

Does that make sense? A solo handyman typically can't do more than one thing at a time, so the load is actually quite low.

Aluminium is and excellent choice for feeder applications. An anti-oxidant MUST be applied at the terminations.

Happy Thanksgving

Andy

LawnGuyLandSparky · 11-22-2007, 07:58 AM

Do what Andy said. Unless you're going to run electric heat, you would never be able to use more than one tool at a time. IMHO even 40a 240v would do fine.

220/221 · 11-22-2007, 01:31 PM

Bigger is better.

Why install the minimum?

If it's a garage he or somebody in the future may want to weld someday.

If there are no other limitations, go big.

Stubbie · 11-22-2007, 10:48 PM

All this talk about minimums and maximums is pointless. Bigger is not better. 60 amps will take care of 99.9% of garages. No one has mentioned the word shop where several large amperage tools may come into play. 60 amps will handle welding and a compressor plus lights. Even the Lincoln stick welders can be operated just fine with a 60 amp feed. They only have 20% duty cycles. A 100 amp feed is for a "shop" not a garage. Poster says this is a garage fed from his landlord panel which is no where near its demand max. assuming it is A 150 amp panel and fed with a 150 amp service. I see no reason to waste his money on conductors that are likely to be never utilized to the capabilities and the cost difference is substantial between the wire sizes.

Econoline:

What are your expectations now and down the road a few years as far as power tools and equipment...ie window a/c, welder. compressor or just lights and receptacles and a hand drill or sawsall once and a while?