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steve7_11 · Jan 9, 2008, 10:57 AM

Hi all!

I am a woodworker and need to install a sub panel in my attached garage. The main is a 200 amp panel and my home was built in 2001. I live in AZ and spoke with the city who said they go by the NEC 2005.

I was thinking of running a 60 amp sub panel as this should more than meet my shop needs for now.

I will be running two or three 120v circuits (one for air compressor, one with multiple outlets for several power tools running one at a time, and one for dust collector to run with power tools on a separate circuit) and one or two 240v circuits (one for band saw, one for table saw, and maybe one open for expansion down the road) from the sub panel and possibly expanding down the road.

1. Is 60 amps enough and are there enough panel openings on a 60 amp panel for this many separate circuits?

2. If I go with a 100 amp sub panel, can I just run a 60 amp breaker in the main and sub panel? (I think the answer to this is yes as I have searched this forum previously? )

3. The BIG one I need clarification on….. what cable should I run to the sub panel? #6 for 60 amp or what for a 100 amp? I have almost 100 feet from the main panel to the location of the proposed sub panel location and am obviously concerned with voltage drop. I’ll be running everything through the attic.

4. Also, do they make larger gauge cables that are “all-in-one” cables or will I need to buy three separate cables and a ground wire?

5. Since my garage is attached, I just want to make sure I don’t need a ground rod on the sub panel. My understanding is that I will connect the two Hot Wires to the Hot Bus Bar and the Neutral to the main Neutral Bus Bar terminal and the separate ground to the Ground Bus Bar??

I’m not an electrician, obviously, but have done a lot of reading on this and just want to make sure this seems correct.

I really appreciate any guidance anyone can give me. Thanks so much.

-Steve :cool:

tkrussell · Jan 9, 2008, 03:52 PM

My answers are in bold:

1. Is 60 amps enough and are there enough panel openings on a 60 amp panel for this many separate circuits?

To size a feeder and a panel, need to know the load of each tool and circuit. The load can be in amps, wattage, or horsepower. I suspect 60 amp is fine, but I cannot speculate without knowing the load.

2. If I go with a 100 amp sub panel, can I just run a 60 amp breaker in the main and sub panel? (I think the answer to this is yes as I have searched this forum previously? )

Yes.

3. The BIG one I need clarification on….. what cable should I run to the sub panel? #6 for 60 amp or what for a 100 amp? I have almost 100 feet from the main panel to the location of the proposed sub panel location and am obviously concerned with voltage drop. I’ll be running everything through the attic.

I would run, if allowed in your area, #2 aluminum, or #4 copper, for either 60 or 100 amp feeder. This will solve the voltage drop issue.

4. Also, do they make larger gauge cables that are “all-in-one” cables or will I need to buy three separate cables and a ground wire?

#2 aluminum is available in a 4 wire cable assembly, called SER cable. Copper cable is available but only from an electrical distributor.

5. Since my garage is attached, I just want to make sure I don’t need a ground rod on the sub panel. My understanding is that I will connect the two Hot Wires to the Hot Bus Bar and the Neutral to the main Neutral Bus Bar terminal and the separate ground to the Ground Bus Bar??

Correct, a ground rod is not needed for a subpanel that is in the same building as the Main panel, only needed for a separate building. Keep the neutral isolated and insulated fro any equipment grounds, do not install the screw that comes with the panel intended for bonding the neutral bar to the metal can.

Since your not an electrician, you will be applying for a permit and inspection from your local building dept?

steve7_11 · Jan 9, 2008, 04:17 PM

Thank you so much for your response, sir.

What a great resource this website is and kind folks like yourself anwering these questions so quickly. I really appreciate it.

And yes, I'll get a permit for the job, but wanted to make sure I was on the right track first. Thanks again.

Steve

tkrussell · Jan 9, 2008, 05:41 PM

Your welcome.

The promptness is purely right place right time.

Certainly does not happen for every question.

Talk this over with your inspector before doing any work or buying material.

Hopefully he will be consultative and give a few tips. But don't take it personal if he is a prick. They are not suppose to offer any advice , at all. But most will tell you if what your planning is correct. Keep in mind, some do not care for homeowners doing their own work, even thou it is allowed by state law.

Can't say I blame them, sometimes.

Cobraguy · Jan 10, 2008, 06:34 AM

I live in Phoenix. I installed a sub in my garage/shop. The first thing I wired for was an air conditioner. Believe me... that isn't a luxury around here in the summer. I would plan for that if you plan on doing anything in your shop other than the hours of 3:00 a.m. to 9:00 a.m. At least the temp in the garage will be down to about 100 degrees during those hours...

steve7_11 · Jan 10, 2008, 07:51 AM

Thanks for the response, Cobraguy.
I've spent the last couple of summers out there in the heat and can definatley appreciate the idea of AC in the shop. I'm leaning toward the 100 amp sub panel so I can expand down the road and maybe treat myself to some AC in the summertime!! (Or I can just come over and work in your shop!! :) Just kidding, but thanks for the input.
-Steve