Shop Wiring

jbolt

jbolt

Active User
H-M Supporter Gold Member
Joined
Dec 3, 2013
Messages
1,844
I’ll start by qualifying that I am a general contractor with over 30 years of experience in home building and renovation. I’m well versed in household electrical so I’m good on means, methods, codes and safety.

In the spring of next year I’m having a local contractor insulate and drywall my new (to me) shop at our Oregon property. The shop is 28’ x 32’. It currently has a subpanel feed by a 60 amp breaker with #4 wire. There are 110v convenience outlets every 4’ around the perimeter walls about 4’ off the floor. These are divided on three separate 20 amp breakers.

I need to get the wiring sorted out before finishing the interior can begin and I’m waffling about the best way to proceed. My current plan is to run a feeder to another subpanel on the opposite side of the shop to feed the circuits on that side which would cut down the amount of wire needed to be run from one location.

All the 220v circuits would be surface run in conduit after the walls are finished. I just don’t know what the final equipment layout will be until we get up there full time in a few years so I think it is better to surface run.

The lighting wiring can be run in the walls but I’m debating whether to leave the 110v outlets in the walls or strip that out and run everything in conduit? I’m not a huge fan of surface run conduit but it makes the most sense to me for customization and expandability.

If anyone has been through something similar I would appreciate your thoughts.

As to lighting, for a shop of this size with a 12’ ceiling how many lights would you recommend? I like lots of light.
 
Not nearly as big, but I recently installed a bunch of wiring in my garage shop with an electrician inspection. I ran a 100A subpanel from my main, it was reasonably accessible and if I'm pulling wire, might as well. I also have an EV charger, so that needed a bit of power. I think your plan to put another panel on the opposite wall makes a lot of sense and I would do that in-wall if you can. If nothing else, you avoid running into issues with conduit fill and derating pulling everything from the other side. And it's easier to add more conduit as needed, you don't have to go all the way around the building, just to the closer box. I already had to add another conduit across the ceiling due to that.

I would leave the convenience outlets and add to it later with the conduit runs. Mine is done all with surface conduit, which IMO looks good enough if you are careful.

I ran 2 MWBC circuits to the shop area, alternating every other box for 110V. So I can run higher power drain 110V loads without tripping breakers so much as they won't be sharing often. I couldn't run a vacuum and the miter saw before. Irritating.

I already had a 220V 40A over there, but I added some lower amperage 220V for the mill and grinder so I can leave the larger one for welding. I also added a couple circuits on the garage side as we were always running out and there was only one circuit in there before. We'd managed to trip the garage circuit a couple times using things in the yard as well. Now that stuff has a pair of dedicated circuits to work with.

I'd plan for lots of lighting. But it doesn't need a lot of power if you're going to use LED or fluorescent. If you want to do in-wall, you could set boxes and/or outlets in the ceiling on a grid and just use them as needed. I'm using LED and have loads of light only drawing about 2A.
 
In a shop, surface wiring in conduit is the only way to go for everything IMHO. It's easy to make changes and matches the later additions when you need them. It's a little more work but worth the effort in the end. Plastic conduit is cheap and easy to install, but use metal boxes. Surface mount the breaker panel also.
 
The spacing for your outlets are typical for a general use shop layout. Unless they are in the way of future wall mounted cabinets I would leave them as they are then surface mount dedicated circuits when size needed and location is determined. Your lighting question is more difficult not knowing the type of lighting you want. I have 10 2x4 3 lamp florescents with an 8' ceiling and it is adequate but not great.
Jay
 
Lighting- my shop is 24 x28, 10' lid, sheetrocked but not painted. 2 windows, 4'high, 5'wide, both facing southwest. Built the shop when I was 28 years old. At that time, I hung 4 two bulb flourescents. Plenty of light for me then.
Fast forward to today- I am 58, with great eyesight according to the Doc. I have 20 4' bulbs in there now, with 300W halogens on arms above 3 different workstations. Portable LED worklights and flashlights all over the place. Seriously considering a move to all LED, because I am at the limit of what my lighting circuits in the panel will support.
 
Although I did not do it in my home shop, I like to use gutters the full length of a shop, this I did when I wired my former shop downtown, that way, you can run suitably large wire the full length of the shop and tap into it at any point, and locate sub panels below it and run wire either direction inside to feed machinery as needed, it allows changes to be made easily at any time after the initial installation.
 
If the 110v outlets are already there, I'd leave them.

WRT lighting, I just went to 2'X4' LED panels. The ones I bought were 5800 lumens, and for my 8' ceiling, I used 4 for general lighting in a 25' X 25' shop - yes 4. Over the bench I used 2 800 lumen 8" X 8" panels and my bench is very well lit. Over my lathe I am re-purposing an 4X4' fluorescent fixture for use with retrofit LED bulbs, 300 lumens apiece.

Over my mill I'm thinking to use 2 double fluorescent fixtures wide spaced for general light around the table. All machines have work lights, of course.

I like the idea of surface mounting your machine specific power. I ran all mine in the walls and it isn't the best.
 
Is 60A enough? What are your major power users? Are you going to have electric heat or air conditioning? Electric hot water heater? Welder, compressor, dust extraction, ... ? How many 220 machines? Any 3-phase?

Do you foresee ever having more than one person working in the shop at a time?

I would think that with modern lighting, you could get good illumination without using a lot of power but I can't help with specifics. Otherwise, your plan for 110 and surface mount 220 sounds sensible.

Craig
 
My shop has 60A 220V feed. I use a Miller 300A welder, and all my 3ph machines on it with no problem. I can only use one machine at a time....
 
WCraig said:
Is 60A enough? What are your major power users? Are you going to have electric heat or air conditioning? Electric hot water heater? Welder, compressor, dust extraction, ... ? How many 220 machines? Any 3-phase?

Do you foresee ever having more than one person working in the shop at a time?

I would think that with modern lighting, you could get good illumination without using a lot of power but I can't help with specifics. Otherwise, your plan for 110 and surface mount 220 sounds sensible.

Craig
Click to expand...

60A is plenty. The feed wire from the main is rated for 75 amps so I could up the subpanel to 70A. All my 220v machines are 25A or less with the welders pulling the biggest draw. Not planning to have employees so at most I would be running my CNC mill and another machine at the same time. I do that now on a 30A breaker. Shop will be heated with a gravity feed pellet stove. No power required.
 
You must log in or register to reply here.
Back
Top