Shop wiring questions / advice requested

[David Wambolt]

I'm seeking some advice from those individuals who have custom wired their shops to support multiple different machines, both 110 and 220 volts. I have a mixed variety of equipment that runs on either 110/220. I also have welding and plasma cutting equipment, so I need 220V power for that stuff. I want to finalize my wiring plans for my 20x24 shop. It's not huge, but I built it myself and it fits on the residential city property. It replaced a 15x24 structure that was a total POS and was literally falling down. I made use of my larger/deep lot and installed dual 12' garage doors so that you can drive a vehicle thru the garage. I'll then have a rear driveway behind the shop big enough for two vehicles or a vehicle and a trailer along with a nice large shed. In front of the shop is a single car driveway long enough to park almost 3 vehicles before the gate that seperates the front yard from the back yard.

Anyhow, back to the wiring. I just had my main house panel replaced with a Siemens 200amp panel that has plenty of space to grow. I went from a 60amp fused service to this (house was built in 1950). I then had a 125amp Siemens 12 position, 24 circuit sub-panel installed in the detached garage/shop fed by a 100amp breaker in the main panel. I have plenty of power coming into the shop to run all of my equipment. The circuits I have drawn up so far are:

1. 120V, 20A, 6 Outlets (General Use, Branched, 12/2)
2. 120V, 20A, 6 Outlets (General Use, Branched, 12/2)
3. 120V, 20A, 1 Outlet Dedicated (Dust Collector, 12/2)
4. 220V, 20A, 3 Outlets (General Use, Branched, 12/2)
5. 220V, 20A, 3 Outlets (General Use, Branched, 12/2)
6. 220V, 20A, 1 Junction Box (1.5 Ton Mini-Split HVAC / Heat Pump, 12/2)
7. 220V, 50A, 1 Outlet (Welder, 6/3)
8. 220V, 30A, 2 Outlets (Table Saw, ?????, Branched, 10/2)
9. 120V, 15A, Lighting (Interior Fluroscent, Attic Lighting, 14/2)
10. 120V, 15A, Lighting (Exterior Front, Exterior Rear, 14/2)
11. 120V, 20A, 3 Outlets (Garage Door Opener, Front/Center/Rear, Branched, 12/2)
12. 120V, 20A, 4 Outlets (Ceiling Drops, Jet Air Filtration, Branched, 12/2)

With the combination of breakers I'm using, that leaves me a few breaker positions open for future growth, though I don't anticipate much, if any.

My real question is, what type of plugs/recepticals are you guys using in your shops? I'm pretty much set on twist locks, but I wanted to be sure before I go purchase them. As for branching the 220V circuits, I'm a one man shop and only use one machine at a time. Wiring wise, this is a pretty basic installation. It's just a lot of wire to run.

Thus far I have completed the rough in of circuits 1,2 and 4. Distance between outlets is about 4'. All of my outlet boxes on the walls are installed. I'm really trying to finalize any drops in the ceiling. I wasn't thinking about any outside of my door openers and Jet air filter, but now that I'm looking at the space it might not be a bad thing to have some places to plug stuff in without having the cords going across the floor. I'll be installing six boxes to run my T-8 fluroscent lighting (6 total 8' fixtures with 24 total 4' T-8 bulbs). I'll have 3 rows, each being 16' long which I think will be sufficient for the space. Any thoughts or recommendations would be appreciated before I continue further rough in. I have a really solid idea of what I'm trying to do, but I figured I might as well ask. I might go "Yeah that's a good idea". It's far easier to run the wiring now before I insulate and drywall in the interior. By the time I'm done, my name will be Mr. Romex. :)

Thanks!

[Mike Jobe]

Sounds like your shop size and tool mix is pretty much identical to my shop. And it sounds like you have planned it out well. I wired my shop and want to make a couple of points that might help. As far as the receptacles, 110V, I used the normal household plugs and receptacles, with 220V I used the locking plugs exclusively, they are less likely to unplug because of vibration and they are typically larger in size to accommodate the larger gauge wire. I used power poles after I located my equipment in the shop, I didn’t like the idea of having conduit spanning across the floor for mid shop located tools such as my table saw (pain to sweep around). One regret I have was the use of the plastic blue 4 squares in the walls; they are not rigid enough to handle continuous use. In retrospect I should have used the steel 4 squares. Lastly, if you haven’t done this yet bury an independent ground rod just for the shop, I would not depend on the home ground rod due to distance. Good luck to you sound like your having fun.
My 2 cents.

[Ben Grunow]

Garage door openers have to be on their own circuit as far as I know. Other stuff sounds good. Make sure to add some overhead power on retractable cord reels. Working without the weight of the cord is great.

Old Mr. Romex

[David Wambolt]

Thanks guys for the input. I did use the blue plastic boxes, but the ones I got for the 220V outlets attach with four nails or screws and are quite rigid.

I'll probably go ahead and run a dedicated 120V circuit for ceiling wiring to use with cord reels. I just got back from the shop and finished roughing in the dedicated circuit for my dust collector and installed the two power feeds to the switch box for my lights.

As for my garage door opener(s), the front/central/rear outlet arrangement is specifically for them. I have not decided if I'm going to use standard door openers or something like I-Drives. This gives me the flexiblity to plug in the opener at which ever place for just a bit of cost in Romex.

Lastly the mentioning of the ground. My shops sub-panel is 10 to 15 wire feet away from my main panel with a four wire feed, including a very heavy duty ground. So I think I'm okay.

[Roy Wall]

David,

I used the twist locks - based on good recommendations from fellow creekers. two 20 amps and a 30 amp in a little sub panel (garage shop). Like you , one tool at a time with a Cyclone DC running.....

[Rick Christopherson]

It sounds like you've planned this out very well and given it plenty of thought. Do you have any convenience outlets outside the building? I would also put in a quad outlet near the overhead door close to the driveway for use in the driveway.

If you have multiple entrances, make sure to put in 3-way (or 4-way) light switches at each entrance. Also, since your primary lighting is flourescent, you may want to put in a utility light circuit for those quick grab-and-go times, especially if you live in a colder climate.

[Rob Will]

David,

I would consider using 10-2 rather than 12-2 on certain things:
Dust Collector,
Heat Pump,
and......where's your Air Compressor?
All of these items run a lot, start frequently, and could end up being heavier than what you have now. I would also consider taking all of these items to 220V.

On the ceiling lights, I would take that circuit to 12-2 rather than 14-2.

Rob

[Richard Butler]

That layout is better than many homes. How many people are going to be working in your shop at once? 12?

[Bill Brady]

You will want to use standard receptacles on the 120v circuits, but spend a little more and buy good receptacles they will stand up to the pluggin the tools in and out. Also wrap the wires around the screws to make the connections, don't use the push in spring contact these will work loose with time. Remember it will be considered a garage so all receptacle circuits will need to be ground fault protected.

[Bernhard Lampert]

Ditto, what everyone else said. And it looks to be a nice and complete design.
One more caveat: Depending on your location and designation of the building, all 110V DCO's (i.e. all non-dedicated 110 outlets) need to be GFCI.
I just recently completed my shop (well, still need to run final dust collection and compressed air piping). I run all electrical exposed in EMT (3/4') fed from attic space. In the attic everything is run in non-metalic tubing (Smurf tubing) for ease of handling. This arragement allows for later changes/upgrades. Also, I did stay away from plastic boxes...they just don't hold up.
On last comment: I purchased all my twist lock plugs/receptacles for single and 3-phase(L6-30 and L14-30) on Ebay. If you are a bit patient and are buying in bulk (i.e.5 of more) you can still get excellent 'deals'. For example, I bought 10 plugs (L6-30, Nylon, Levition, NIB) for $65 just a couple weeks ago!!
Looks like you will have a really nice shop!
Cheers,
Bernhard

[Rick Christopherson]

I purchased all my twist lock plugs/receptacles for single and 3-phase(L6-30 and L14-30) on Ebay. Just so you know, the L14-30 is not a 3-phase plug. It is a 120/240 single phase plug.

[Mike Seals]

Lastly, if you haven’t done this yet bury an independent ground rod just for the shop, I would not depend on the home ground rod due to distance. Good luck to you sound like your having fun.
My 2 cents.

Mike, it is not a good practice to run a seperate ground rod in a home enviroment, unless you connect them together with a common cable, usually underground. It sets up possible stay currents floating around in your electrical system. You probably would never notice them, but some of you electronic equipment will.

[Rob Russell]

Mike, it is not a good practice to run a seperate ground rod in a home enviroment, unless you connect them together with a common cable, usually underground. It sets up possible stay currents floating around in your electrical system. You probably would never notice them, but some of you electronic equipment will.

Actually, installing a ground rod at a separate structure is a requirement under the NEC (look at article 250.50), but municipalities definitely enforce that differently.

[Rob Russell]

David,

Your overall wiring plan sounds good. I agree with adding a circuit for an air compressor. I'd also plan on the dust collector being a 240v circuit, so allow 2 slots in your panel when laying out the breakers.

Rob

[Mike Seals]

Actually, installing a ground rod at a separate structure is a requirement under the NEC (look at article 250.50), but municipalities definitely enforce that differently.

Rob, section 250.32 covers this, exceptions are for things just like the shop. As long as the equipment ground is routed to the other panel, no ground rod is required.

[Mike Jobe]

Greetings,

Mike, Rob, in my application, my shop is at least 80 feet from the main box in the house, I grounded at the main junction (house) as well as the shop panel, knowing this, would it still be your recommendation to not ground the shop independently? I was told this was wise to do so, if that is not the case please let me know and I will pull that second ground.

thanks
Mike

[Jim Becker]

The electricians who did my 200a service to the shop building did not put a ground rod there. All the grounding was done at the main service enterance. Now, this may be because it's branched from the meter, rather than in the main panel. (There is separate cut-off/breaker for the lines to the shop building next to the house panel, but it's independent from the house panel)

[Pete Brown]

The electricians who did my 200a service to the shop building did not put a ground rod there. All the grounding was done at the main service enterance. Now, this may be because it's branched from the meter, rather than in the main panel. (There is separate cut-off/breaker for the lines to the shop building next to the house panel, but it's independent from the house panel)

The inspector made the electricians sink two ground rods at my shed, and sink a second one at my meter, and make sure the ground was common across all. My workshop service runs off of a 100amp breaker in the house, though.

Pete

[David Wambolt]

Alright guys, I read through everything. Some points taken:

1. L6-20, L6-30 Connectors will be used for my wood working equipment that is powered by 220V.

2. Dedicated dust collector circuit will initially 120V, but can be converted to 240V by simply swapping the breaker and plug.

3. I will run a service loop of 10/2 wire into the attic space for a 6hp compressor circuit. My current compressor is 120V. Long term I plan to build a compressor room behind the shop to hold my dust collector and compressor, along with misc storage (5x8').

4. I'm going to replace my 12 spot Siemens panel with a 20 spot Murray panel. That will give me the freedom of more 220V circuits. The cost was $66 at Home Depot for the panel and since the electrician made a roofing error when putting in my weather head, I have to pull the cables anyway to fix the roof issue. It's not a big deal but since I'm already there I figure replacing the panel will be a wise decision for little cost and allows me to have a spare Siemens sub-panel for any other projects I come up with. :)

5. I'm adding 60A disconnects for my two 20A 220V general purpose circuits. That will allow me to power down the machines without unplugging them when I'm done, instead of flipping breakers.

6. I will add a ceiling circuit for cord reels and also put a couple L5-20 twist locks sockets on it for a drop whip.

[Rick Christopherson]

my shop is at least 80 feet from the main box in the house, I grounded at the main junction (house) as well as the shop panel, knowing this, would it still be your recommendation to not ground the shop independently? I was told this was wise to do so, if that is not the case please let me know and I will pull that second ground.No, I would keep the additional ground rod(s). The farther away you get from a ground rod, the greater the possibility for a voltage differential between the grounding system and the physical ground (Earth).

You can have as many ground rods as you want as long as it is a unified grounding system and not separate grounding systems. I always recommend adding ground rods for separate structures.

[Rob Russell]

Rob, section 250.32 covers this, exceptions are for things just like the shop. As long as the equipment ground is routed to the other panel, no ground rod is required.

Mike,

The exception to 250.32 applies to a "single branch circuit" and also allows that "a multiwire branch circuit shall be considered as a single branch circuit". The exception does not apply to a feeder used to supply power to a panelboard, i.e. a subpanel.

Rob

[Rob Russell]

No, I would keep the additional ground rod(s). The farther away you get from a ground rod, the greater the possibility for a voltage differential between the grounding system and the physical ground (Earth).

You can have as many ground rods as you want as long as it is a unified grounding system and not separate grounding systems. I always recommend adding ground rods for separate structures.

Rick,

I assume you advocate this providing that the additional grounding electrodes are connected to the EGC and that the system is bonded only at the service equipment. Is that assumption correct?

Rob

[Mike Seals]

Mike,

The exception to 250.32 applies to a "single branch circuit" and also allows that "a multiwire branch circuit shall be considered as a single branch circuit". The exception does not apply to a feeder used to supply power to a panelboard, i.e. a subpanel.

Rob

Got online at work today and looked up the most recent NEC. You are 100% correct. Seems strange that when I bought our house in 2001 that the inspector did not catch this, I wasn't looking for it either. Been in these plants too long and have strayed away from the real world.

Oh well, I was planning on an upgrade to our service, going underground and using a seperate feed for the shop. Hurricane Rita drove the copper prices here through the ceiling so I've not moved on that yet.

[Mark Saberniak]

I ran all my wires from each receptical to the attic into two large boxes one labeled 220v and the other labeled 110v. if i want to change any outlet to a different voltage all i have to do is go to the boxes and pull the wires out of one box and into the other. I then change the outlet style to the appropriate type. I have many times been thankful I did this.

[Michael Lutz]

I would just make all the 220V out 30A, so I only had to have one plug type which could fit into the 220V circuits. It would give the flexibility to put your 30A equipment any where in the shop. Or you could just wire the 20A 220V circuit using 10-2 wire so you can upgrade the plugs and breaker if necessary in the future.

Mike

[David Wambolt]

Too late for my wiring project, plus I'm already blowing the budget out of the water with this whole shop 'thing'. My rough in is mostly complete and came out nicely. I just have another circuit or two to run for garage door openers, HVAC, and I need to finish up my interior lighting runs. Most of my equipment draws well under 20A at 220V. I have two dedicated 30A 220V circuits, in additional to the common 20A 220V circuits. I already had extra 12/2, I had to buy 10/2. I can't imagine I'm going to be hurting on power in my small shop. I have a 20 spot Murray/Siemens panel installed now instead of the original 12 spot that my electrican installed. I just swapped it out for $66 from Home Depot and it took about an hour including fixing a roofing error they did when the poked through for the weather head. I ran some 6/2 for two dedicated 50A welding circuits for my TIG/MIG/Plasmas. Anyone who has seen my shops electrical rough in has mostly went either "holy crap" or "you're nuts". So I think I got it right from a guys perspective. :) haha.

Insulation, Drywall, and paint come next week.

[David G Baker]

Too late for my wiring project, plus I'm already blowing the budget out of the water with this whole shop 'thing'. My rough in is mostly complete and came out nicely. I just have another circuit or two to run for garage door openers, HVAC, and I need to finish up my interior lighting runs. Most of my equipment draws well under 20A at 220V. I have two dedicated 30A 220V circuits, in additional to the common 20A 220V circuits. I already had extra 12/2, I had to buy 10/2. I can't imagine I'm going to be hurting on power in my small shop. I have a 20 spot Murray/Siemens panel installed now instead of the original 12 spot that my electrican installed. I just swapped it out for $66 from Home Depot and it took about an hour including fixing a roofing error they did when the poked through for the weather head. I ran some 6/2 for two dedicated 50A welding circuits for my TIG/MIG/Plasmas. Anyone who has seen my shops electrical rough in has mostly went either "holy crap" or "you're nuts". So I think I got it right from a guys perspective. :) haha.

Insulation, Drywall, and paint come next week.
David,
I get the same response from folks that look at my electrical set up. I spend the bucks and go all out trying to cover almost any eventuality. Ya never know what you might need. I do everything by the book. I spend a lot of time on the Mike Holt NEC site.
I have a lot of wire on hand that was purchased prior to the horrible price increase.
David B

[David Wambolt]

I have completed my rough in and it looks good. I only made one error during the installation of my rough in. I forgot the ceiling circuit for my Jet Dust Filter machine. I'll have to fish a wire down from the top plate and into my sub panel and install a single gang box in the ceiling about 12' from the sub-panel. Not a big deal as I drilled extra feeder holes in the top plate above my sub panel box already. I was wondering... "why do I have two 20A circuits open?". That explains it. :)

I took last week off so that I could lay some OSB down in the attic for storage and then insulate with R13 and R19, plus install armored drywall. I almost completed the first coat of tape and mud today, but I have to be honest it's not my forte and I was just tired of slinging mud.

Here's some pics. I hope to have the final coat of paint on this coming Sunday. The following week I'll install all my standard and twist lock recepticles and then I can start unboxing some of my new zoomy tools. I built this garage for my aunt a couple of years ago. However she got sick and now is unable to care for herself. So I'm buying the house and while it needs a lot of TLC, I'll be able to make it into what I want. At least now I'll have a place to work out of.

The only thing left after the drywall is textured and painted is to install a mini-split 1.5 TON 13 Seer Heat Pump / AC system, build some cabinets and get to working!


Pics: http://www.dmwtech.com/gallery2/v/construction/garage/