Electric power

[g+16]

O.K. all you wiring guys out there, attached garage needs wired. 24x30 ft. maybe 6-8 ovh strip lights, 10 to 12 110v outlets, 2 garage door openers, bench grinder and air compressor from time to time. Have been told use a 100 amp. box, with 30 amp. double brecker, run proper size wire for 30 amp. to main fuse box in house. Is it really that simple? No newby to wiring, proper ground and what-no, but someone has always had to tell me the proper box,breckers ect. Is this imformation corect? and what amp. becker do I use in the main box. Any information helps, thanks

 

[hornadylnl]

I'd go with a bigger service than 30 amps. What size compressor?

 

[eldirector]

I have a 50A circuit to my detached garage/shop. There is a 50A breaker in the main (200A) panel run to a subpanel in the detached garage. Runs my 220V heater, 220V welder, 120V compressor, and 8 pairs of 4' lights. Oh, and the little garage fridge.

30A really isn't all that much. Heck, I'm really at the limit of my 50A in the winter, with the heat running.

 

[bass pro]

I do electrical work and would be happy to help wire your garage. PM me with contact info.

 

[hornadylnl]

I have a 50A circuit to my detached garage/shop. There is a 50A breaker in the main (200A) panel run to a subpanel in the detached garage. Runs my 220V heater, 220V welder, 120V compressor, and 8 pairs of 4' lights. Oh, and the little garage fridge.

30A really isn't all that much. Heck, I'm really at the limit of my 50A in the winter, with the heat running.

I've got 200 amp going to mine.

 

[Joe G]

I've got 200 amp going to mine.

That's a LOT of power reserve!

 

[GodFearinGunTotin]

O.K. all you wiring guys out there, attached garage needs wired. 24x30 ft. maybe 6-8 ovh strip lights, 10 to 12 110v outlets, 2 garage door openers, bench grinder and air compressor from time to time. Have been told use a 100 amp. box, with 30 amp. double brecker, run proper size wire for 30 amp. to main fuse box in house. Is it really that simple? No newby to wiring, proper ground and what-no, but someone has always had to tell me the proper box,breckers ect. Is this imformation corect? and what amp. becker do I use in the main box. Any information helps, thanks

The answer is: "It depends".

It depends not only on what you've got to power up now, but also what you may want to do in the future. The difference between a 30 amp circuit and a 100 amp circuit may seem like a lot now. But wait until you get your shop finished, insulated, dry walled, etc. and 2-3 years from now you decide to start some new hobby or something and now need that extra juice.

It's just me, but I always 'over build' everything.

I don't have my code book in front of me but it has some requirements in it for sizing circuits for different types of applications. But going off the top of my head, if you're dead set on doing 'the minimum', I'd add up all of the loads that are likely to be on at the same time and I multiply that total amperage by 1.25. Then round up to the next highest standard breaker/circuit size. Things like garage door openers, I wouldn't worry about because they're usually very small loads and are on for short amounts of time and are used relatively infrequently. For occupancies, IIRC the code has a requirement to estimate the load for the number of receptacles on a circuit. I don't think it applies to a garage, but you use it for estimating purposes...now if only I could remember that number...It's something like 30 watts per outlet. I'll try to look it up and edit this later.

Hope that helps.

ETA: That didn't take long...each receptacle counts as 180VA of load in your estimate:

Q. What is the maximum number of duplex receptacles on a two-wire 20 ampere circuit?

Section 220-3(c)(6). The NEC does not have a specific rule that says 10 receptacles on a 15 ampere circuit or 13 receptacles on a 20 ampere circuit. For 15 ampere circuits, the calculation is as follows: 120 volts x 15 amperes = 1800 VA/180 VA = 10 receptacles, and for 20 ampere circuits, 120 volts x 20 amperes = 2400 VA/180 VA = 13 receptacles.

Many people think that when calculating the number of receptacles the load should be reduced by 80%, but this is not the case! Yes, the NEC limits the load on receptacle circuits to 80% for portable appliances [210-23(a)] and, yes, the maximum continuous load on a branch circuit shall not exceed 80% of the circuit rating (protection device) [220-3(a) and 384-16(c)], but these rules don't apply to the number of receptacles per circuit. I wish the NEC were more specific, but it's not.

 

[hornadylnl]

That's a LOT of power reserve!

400 amp transfer switch with 200 to the house and 200 to the barn.

 

[Mgderf]

I wouldn't go less than 60 amp to the garage. That will run everything you listed, and give you a LITTLE bit of room to grow.

 

[Joe G]

400 amp transfer switch with 200 to the house and 200 to the barn.

Nice!

 

[Joe G]

I wouldn't go less than 60 amp to the garage. That will run everything you listed, and give you a LITTLE bit of room to grow.

Agree.

60A is usually the minimum unless it's literally just a bare garage where you'll just park a car and store the mower. If it will be used as a shop (even a small one), then 60-100amp is the typical range.

 

[g+16]

Thanks to you all for your input and help.

 

[Mr Evilwrench]

I just ran circuits from my main box to the garage, but it's attached. There's the original 15A that runs the lights, fridge, door openers, a few outlets, then there's a 15A for the compressor and the detached shed (with GFI), a 20A for drop cords for the saws, drills and whatnot, and a 30A 240V for welders. The first was all that came with the house, the rest I've added. Oh, and I use a kerosene heater rather than electric. If it was detached, yeah, 60A 240V at least. How many table saws are you planning to run simultaneously, anyway? Get a few lights turned on, run your tool, you'll be fine.

 

[Joe G]

There's the original 15A that runs the lights, fridge, door openers, a few outlets,

FYI... fridge is usually on it's own circuit.

 

[Mr Evilwrench]

I plugged the fridge in before I put any of the other circuits in.

 

[Kernal1984]

Go with 100 amps if its possible, the additional cost is minimal comparatively and you will be happy to have the extra juice down the road.

 

[Caleb]

I'm looking to add a welder soon to my parents garage(no garage at apartment complex), currently disconnected one of two big electric heaters to provide 220v to my compressor. Works fine for compressor, but the welder requires 50amp itself...house is 200amp, iirc garage is 100amp piggybacked to the house circuit.

I believe each heater is on it's own 30amp, but I was considering upgrading the breaker for that one heater and the wire running to it to handle 50amps...will I have any problems here?

 

[GodFearinGunTotin]

I'm looking to add a welder soon to my parents garage(no garage at apartment complex), currently disconnected one of two big electric heaters to provide 220v to my compressor. Works fine for compressor, but the welder requires 50amp itself...house is 200amp, iirc garage is 100amp piggybacked to the house circuit.

I believe each heater is on it's own 30amp, but I was considering upgrading the breaker for that one heater and the wire running to it to handle 50amps...will I have any problems here?

Shouldn't be. Welders are typically not continuous loads. It's possible, your parents might see some flicker when you strike that arc at the same time their AC, water heater (assuming electric), etc. are all running at the same time.

 

[Caleb]

I can remember if the water heater is electric or gas, leaning to it being gas. How can I reduce the flickering as I'm striking an arc?

 

[GodFearinGunTotin]

I can remember if the water heater is electric or gas, leaning to it being gas. How can I reduce the flickering as I'm striking an arc?

It may not happen at all. And unless it's really pronounced, it shouldn't cause any problems with the equipment anyway.