New Workshop Electrical Question

[Matt Przybylski]

Hello everyone,
Let me preface what I'm about to type by saying I'm a complete electrical newbie and have been trying to learn for the past few weeks in preparation of wiring for my new workshop (3 car tandem garage). I am moving into a new construction home and want to add a bunch of 220 and 110 outlets with surface mounted conduit. I'm trying to figure out if I have the wiring correct as I want a single 20A, 220V receptacle and a duplex 20A, 110V receptacle in each box.

The attached image is of the first run coming out of the panel. My plan is to have a breaker for the 220 and a separate breaker for the 110 in the panel. I want to run all the 220 outlets on one circuit and the 110 on the other in this particular line (there is about 3 of these in different parts of the shop, all on their own dedicated circuits). This run will have 4 boxes (3 of which you see here, one more not pictured but the same as the right two setups continued down the line). I want to make sure that I have the wiring correct as this is the basis for the other two runs as well which would mimic this run but on the opposite wall as well as one on the ceiling.

Could someone much more intelligent than I when it comes to electrical work please let me know if this is wired up correctly or if I'm completely off base? I really appreciate the help as this is nerve wracking for me and I've been trying to figure out how to do it for the past few weeks in my head so I wanted to get something down "on paper".

I'd also like to know if I need to ground each receptacle in the box? If so, how would that work with one grounding screw in the box and two separate receptacles? Would I just add one more ground wire to each wire nut and run them both (one from the 220 and one from the 110 receptacle) to the one ground screw on the box together?

And yes, I know I can hire an electrician to do this but I won't because 1) there is a lot of work to do on this and it will get expensive very fast, 2) I want to (and feel like I need to) learn how to do this myself in case of future expansion and 3) I am already going to be shelling out a bunch of money for furniture, back yard, etc, so I'd like to save here where I feel like I can actually do this myself (hah!).

Here is a link to a larger Dropbox version of the image: https://www.dropbox.com/s/lz2r9d55gr...-wall.jpg?dl=0

wiring-plan-long-wall.jpg

[Joe Shinall]

Let me just say that I was in your shoes before I bought my new house and I have since rewired half the house myself and also wired my entire shop myself. However, let me plead for you to at least hire an electrician to look over your work when you're done before you throw the switch on. I know some electricians around my area that would do it for under a hundred bucks and it's a great piece of mind.

Pretty sure someone's going to agree with me that you shouldn't run that many 220's off one circuit. Unless you are NEVER going to be running 2 220 machines at the same time.

[Matt Przybylski]

Hey Joe, thanks for your input. You're absolutely right, I indeed am hiring an electrician to finish it (connections to the panel) but I want to do as much of the conduit/wire runs/setup as I can myself.

As for never running 2 220 machines at the same time, that is the plan. Never on one circuit. The DC will have its own dedicated 30amp circuit so it shouldn't be an issue.

[Wade Lippman]

It is not 110v or 125v; it is 120v. (actually I have 117v in the summer and 122v in the winter but its called 120v)
Your wiring looks fine, though i would be real uncomfortable doing this if I had never done any wiring. If you can't afford an electrician, do you at least have a knowledgable friend who can look it over before it goes hot?
I have two 240v circuits. One for my cyclone and one for my tools. I've never wanted to run two tools at once, but obviously would have a problem if I did.
Use a plastic box and you don't have to worry about grounding. If you want a metal box then i don't honestly know for sure, but would guess that ground is ground. As long as all the wires pass through all the holes together, the fact that your grounds are effectively joined doesn't matter. Your better outlets self ground to the box.

[Matt Przybylski]

Hey Wade,
Yep, as I mentioned in the comment above yours, I will be having someone look it over before they connect it. I just don't want to do all this wiring and its no good.

[Alan Schaffter]

You might want to check local code. Some states/locales do not allow the tab between each half of a 120V duplex outlet to carry current from one outlet to the next (daisy chain). Instead, they require a pigtail with wire nut be used to connect to the main conductor.

[Doug Garson]

You should also check to see if you need a permit to do this (anywhere I've lived a permit would be required) part of the permit process would be one or more inspections by an electrical inspector. If a permit is required and you don't get one don't expect your insurance to cover you if you have an electrical fire. You might also check your local big box store or electrical supply store to see if they have a homeowner's guide to your local electrical code, it should answer most of your questions.

[Dennis Yamamoto]

One other thing to consider is to install a 220, 30 amp circuit instead of a 20 amp one. 10 gauge wire is a little harder to work with and a little more expensive, but it will save you time in the future if you upgrade your equipment. I'm not trying address the question of 2 machines at a time with this suggestion.

[Matt Przybylski]

Dennis, I will be using 10 ga for the 30a, 220 dedicated circuit for the DC. The others will all be 12 ga.

[Jason Roehl]

If it's going to be in conduit, go ahead and spring for red wire instead of re-labeling the white wire as a hot leg.

When it comes to grounding the boxes, receptacles, and the two circuits, you can tie all those grounds together. Get bigger wire nuts if need be, and use a small pigtail with a crimp-on ring (or forked) terminal to screw it to the box.

[Matt Przybylski]

Jason, I didn't realize you could tie ALL of the ground wires together into one nut and do that. That's a good idea and will probably be cleaner than what I have.

[Steve Mathews]

Matt - I just finished a very similar project in my barn/shop. The major exception was my wiring was run in stud walls where romex type wire and plastic boxes were used. I also used 10 gauge wire for the 240v, 20 amp circuit. Here's what I learned ...

Make sure you use a large enough box to satisfy fill requirements. There's plenty of info. online to do this calculation. Many here will suggest using a larger box than required primarily because of the 10 gauge wire. It will certainly help but I didn't find it necessary.

Be prepared to be a little more patient with the 10 gauge wire and think about how to cleanly fold the wires into the box. It's definitely more difficult to work with but you get better at as you go along.

You will need to get a special cover plate for the duplex and single 240v, 20 amp outlet. They are available but you probably won't find them locally.

I'm not suggesting that you tackle connecting to the panel but I did it without a problem. In all fairness my shop has a separate subpanel where all power could be cut off.

Member Alan Schaffter suggested that "daisy chaining" may not be permissible in your area. You might be able to determine that by simply looking at one of your duplex outlets in the house, especially considering it's newly constructed.

And lastly, I didn't hire an electrician, not to save money but rather for the satisfaction of doing the work myself. The learning process was fun. If there was any part of the work that I felt was not done correctly or not safe I would've backed off and hired someone more capable to do it.

That's my 2 cents worth of input.

[Matt Przybylski]

Steve, thank you very much for your input. I see you're in Kingman, I'm down in Gilbert, only a brisk 220 mile drive away

I found the cover plate I'd need (as well as a bunch of other things which are much cheaper than at the local big box store) at http://www.garvinindustries.com/, oddly enough located in Franklin Park, IL, very close to where I just moved to Arizona from. Funny how all that works out.

I am in fact considering connecting everything to the panel myself, but not until I get someone that knows what they're doing to take a look at what I have done up to that point. I've done research on how to connect the breakers and it honestly doesn't look very hard. I believe all this that I want to do isn't hard, it's just a matter of knowing if I'm doing it correctly thats the crux of the situation. And I completely agree with you about the satisfaction of doing the work yourself. I got quoted >$4,000 for this work as well as some other electrical work I wanted to do around the house (this was the majority of the cost, I'd say probably $2,500 of it give or take, including materials) which I can't swing at the moment with buying a new home and having to furnish it, etc, so I want to do this myself for not only that reason but because I really have been wanting to learn electrical for a long time and I figure this is as good a time as any.

[Steve Mathews]

Matt - I sometimes get to the Phoenix metro area to visit other properties we have there and lately to compete in some airgun competitions. I understand there are also a few good woodworking stores that I plan to visit on my next trip. The drive from Kingman to Phoenix on AZ-93 (soon to be the new US-11) is really quite nice. I hope you like Gilbert and transition to the climate change without a problem.

Yes, I think you'll enjoy doing the work yourself and developing skills for future projects. You are fortunate in that there will be a good source of electricians in Gilbert or surrounding area to use at your discretion, a luxury we don't have in Kingman. Good luck and let us know how you make out.

[Sam Layton]

Hi Matt,

I just finished wiring my shop, (35' x 50'). You did not say anything about your panel, if you already have one, or you are going to purchase one. If you are going to purchase one, get one with a lot of breaker positions. I put in a 200 amp panel with 42 breaker positions. I think I have only a couple positions left.

Where I am, the code says if you have metal boxes they must be grounded, plastic obviously not. I ran 220, and 120 outlets all around my shop. I installed the 120 in one box, and the 220 in its own box. I put the boxes next to each other. To put everything in one box is a lot, especially with 10 gauge wire. I would suggest using metal boxes with the 220, and using twist lock receptacles. When you pig tail your ground wire, take it to the box first, rap it around the box screw, then to your receptacle. One wire grounds both.

Run all the 120 in plastic boxes. I don't like to wire the receptacles like your diagram. I like to pig tail the wires just like you did in the 220. Where I am, code requires 120 outlets to be GFI protected. I like using GFI breakers, and not GFI receptacles.

Run dedicated circuits to everything that could come on at the same time, air compressor, dust collector, etc. If you do work on your panel, stand on a rubber mat...

Sam