Sub (Garage) Panel Feed Questions

[chevy_truck]

First of all I am a very DIY'er. Here is my situation.

My main panel (House) is feed directly from utility pole meter base. The main panel is 200A Square D QO. Now, my garage is 160 feet from main panel to sub panel. Almost half of this run is from main panel through floor joists to through wall location, other half is in 1 1/2" conduit buried 2feet.

Here is my plan, I am looking to use a wood/oil Newmac forced air furnace, a 220V air compressor, 20A 120V mig welder, 15 4' T8 lights, 4 plugs at 20A, 10 at 15A, an outside light (aluminum halide i think).

Now the questions:
1- Is a 40A sub panel enough
2- If it is enough will 8/3 NMWU carry a good solid 40A 160feet without drop
3- Say the Mig welder was in use, half the lights were on, a couple plugs being used, the furnace was blowing, and the compressor started (basically everything running at once). Is there enough Amperage for that, without dimming house lights. Basically i don't want to starve anything for current.

I thank anyone who replies, and am open to any suggestions or concerns.

 

[pattenp]

My quick response is no. I think you'd push through the envelope on the 40A sub service. I'd say you need a minimum of 60A. Perhaps even 100A sub service.

 

[royalton10]

Make sure to get a panel with lots of spaces for future needs. My run from house to garage was 125 feet. I used a 60 amp breaker with #4 THWN copper to allow for voltage drop. Since you are above 100 feet, I would think you also need to allow for voltage drop.

I would bet you would be prettty disappointed if you used #8 wire.

Good luck, post some pictures.

 

[ishiboo]

I am installing a sub in my upstairs, I went with 2-2-2-4 SER as it is basically the same price as 6-3 copper. It's pulled from the main with a 60A breaker for now.

 

[chevy_truck]

I also forgot to ask when I go to ground my sub panel, do I ground to a rod at this location or let the ground carry all the way back and ground through the ground plate attached to the main panel? Thinking of going with NMWU 6/3. This way I can get up to 55A and I am going to use 60A Breaker. I already have a 12 space Square D QO panel comes installed with a 100A Main Breaker. Will 14/2 carry 20A short distances??? I have 3 plugs within 5 feet of each other, but the first one is 20 feet from panel. They aren't accessible and are currently in circuit with 14/2. I am pretty sure I can fish 12/2 to feed the plugs, but impossible to put 12/2 in between plugs. I am just wondering if I should try to go up to 20A or just stick with my original plan with 15A?? Thanks

 

[pattenp]

You need two 8' ground rods driven 6' apart at the garage. If #14 is used in the circuit then the whole circuit needs to be protected with a 15A breaker.

 

[pattenp]

chevy_truck, are you in the US or Canada?

 

[chevy_truck]

Nova Scotia, CAN

 

[pattenp]

Well that explains the NMWU 6/3. I don't know squat about Canada's electrical code requirements. Good Bye and hope you get if figured out okay.

 

[chevy_truck]

I have learned so much in the last two days, by looking through this forum, and asking questions. it is amazing how much a person can help another person, it is too bad more people wouldn't offer their help this way. I have one other questions and then i should be good for electrical, i think i have it pretty much figured out. Most common compressors say 12.5A right??? So would i be doing right by feeding a compressor with 12/3 from a 20A 2P breaker. I don't quite understand, like am I going to fry a 12.5A compressor by supplying it with 20A. Or is the 12.5A Compressor only going to draw 12.5A even if there was 30A feeding it?? This is a stumper. Thank you everyone, this forum has cleared up a really muddy vision of electrical. and NO I am not going to try to be an electrician now, i realize that is better left to a certified electrician.

 

[Aceman]

Most common compressors say 12.5A right??? So would i be doing right by feeding a compressor with 12/3 from a 20A 2P breaker.

You give a piece of equipment the voltage it needs, in this case 240v, and it'll draw as much current as it needs, in your case 12.5 amps. The 20 amp breaker is just there to limit the current and catch a short circuit or ground fault in case one of the wires gets rubbed through, etc.