I want to install a 100 amp subpanel, in my woodworking shop, to carry numerous 110 tools. I will be running it about 90 feet from the main. I have ample breakers available in my main, due to taking out baseboard heaters in my home.

I am totally confused, about what wire I need to run from the main to the subpanel. I was told by one home center that, 2- #6 wires would be sufficent, to run to my 100 amp double pole breaker box, I am using for my subpanel. Then, I was told by another home center, that the 2, #6 wires are only sufficent to carry a 50 amp breaker box. What size wires do I need to carry the load? Can I use 2 #6 wires for the load?

I also need to know, what size ground wire, I need to run from the main to the subpanel.

Any Help or Suggestions?

 

You are getting different advice because the information you provided is too vague. Nobody can give you advice based on that information without making a lot of assumptions, and different people's assumptions are going to be different. The big unanswered question is how big the load is. The amount of power required by a "woodworking shop" can vary considerably depending on the size of the shop, the size of the tools, the number of tools that might be running at the same time, the amount of lighting, and other loads such as heating, air conditioning, a freezer, a garage door opener, a television, etc. The more precisely you can define your load, the better design that can be created.

Having said that, it is almost certain that you don't really need 100 amps. Even though you bought a panel rated for 100 amps, and even though it might have a 100-amp main breaker in it, that doesn't mean that you need to supply it with 100 amps.

Here's my advice, based on my own assumptions which may or may not be good assumptions: Install a 60-amp double-pole breaker in your main panel. Then run either 6/3 UF-B cable directly buried 24" deep, or bury PVC conduit 18" with three #6 insulated THHN/THWN wires plus a bare #10 grounding wire. If the garage is detached, install grounding rods (one or two depending on what your inspector wants) at the garage. And of course be sure to keep the neutral and grounding wires electrically separate at the garage.

If you would care to more precisely define the load as I suggested in the first paragraph, we can fine-tune this design.

 

My workshop 12 x 30, is detached from the house. I have 2 table saws, router, bandsaws, lathe, joiner and other small woodworking tools. I have about 15 total. I will only be running a 110 air conditioner and no other major appliances. I wanted the 100 amp to allow for future growth.

I am running conduit in the ground to the shop. Do I need the ground wire to run in the conduit and also install ground rods? Can I still use the 100 amp box subpanel with the 60 amp double pole breaker in the main? I have purchased 2 100' pieces of #6 THWN-2 or THHN insulated. Do I need 3 strands?

Thanks for your advice!!!!!!!!

 

If you really want the full 100 amps, you need to buy three #2 copper THHN/THWN wires and a #8 copper neutral. But I predict that once you go to Home Depot and see how big #2 wire is and how hard it is to work with, you'll decide that 60 amps is enough. Remember that 60 amps will give you 14.4KW, enough to run about 8 table saws simultaneously. 100 amps will give you 24KW, enough to run about 14 table saws simultaneously.

 

I agree that the 60 amps is plenty. Thanks! You are correct I do not want to work with the #2 wire.

Do I understand you correctly? I need 3 #6 wires and #? (please state size I need) ground wire, run in conduit from the main to the shop. Do I also need to install grounding rods also, at the detached garage??

I appreciate your advice!!!!!!!

 

#10 grounding wire.

Yes, you will absolutely need grounding rods. In many areas, one is enough. Some areas will require two. It depends on local soil conditions. Either ask your inspector, or install two.

 

As a helpful hint from from a DIYer who just did this entire project.. Avoid Home Depot like the plauge.. The prices for electrical supplies are about 10% more then your local electircal supply store.. Look for electrical supply in the yellow pages.

Also the advice you get from the people working there is invaluable. Kinda like having a live doityourself.com bullentin board... Some of the "advice" I recieved at home depot was just wrong and unsafe.

Just my 2 cents

 

Thanks for the input.................I did go to Home Depot and I got the wrong info and the wrong products! A lesson well learned!

Thanks for your 2 cents!

 

Just a point of clarification. When I said #10 copper for the grounding wire, I was talking about the EGC (the wire between buildings). For the GEC (the wire to the grounding rods), you should use #8 (if protected by conduit) or #6 (if not protected by conduit).

 

J. Nelson

You've been a great help. I will be starting my wiring soon and with your advice, it should go well.

Thanks,
Bfixit

 

John is a great help.. Finished up my shed today.. Thanks for all the advice... Now I have to figure out how not to get so dizzy watching the electric meter when my wife turns the kiln on... Yikes....