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Forum topic by Matt Przybylski posted 03-09-2017 03:02 AM 1515 views 1 time favorited 78 replies Add to Favorites Watch
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Matt Przybylski

539 posts in 2213 days


03-09-2017 03:02 AM

Topic tags/keywords: electrical wiring

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!).

The image is showing up really small so here is a link to Dropbox with a larger version: https://www.dropbox.com/s/lz2r9d55grt3fcm/wiring-plan-long-wall.jpg?dl=0

-- Matt, Arizona, http://www.reintroducing.com


78 replies so far

View onoitsmatt's profile

onoitsmatt

367 posts in 1011 days


#1 posted 03-09-2017 03:15 AM

I can’t help you Matt. But welcome to Arizona! If possible get a minisplit in there. That shop will be useless 3 months out of the year without one.

-- Matt - Phoenix, AZ

View JBrow's profile

JBrow

1273 posts in 755 days


#2 posted 03-09-2017 04:22 AM

Matt Przybylski,

I personally would not place 240v and 120v receptacles in the same box. I would rather keep the differing voltages completely separate in separate boxes. I am, however, not sure that this is an electric code requirement.

When confronted with the problem of multiple equipment grounding conductors that must be connected to a single device, I use a wire nut (although copper barrel connectors could be used) to connect the bare copper equipment grounding conductors along with a 6” – 8” piece of bare copper to form a “pigtail”. The 6”-8”length of bare copper that constitutes the “pigtail” is connected to the device (i.e. receptacle) at one end at to the other end to the bare copper conductors.

If the copper barrel connector is used, one conductor in the circuits can be left long enough to connect to the device and the barrel clamp used to bond the other bare shorter copper conductors to the left-long conductor. If there are two separate circuits in the same box, I like to keep the bare equipment grounding conductors aligned with its own circuits (even though back at the service entrance panel, the circuits are bonded).

If the receptacle box is metal then a bare copper equipment grounding conductor must be connected to the metal box and wired into the circuit’s equipment grounding circuit. Since plastic boxes are non-conductive, then no bonding of the plastic box is needed. It is for this reason that I prefer non-metallic boxes. But the device (e.g. receptacle) must be connected to the equipment grounding circuit.

I applaud your do-it-yourself attitude. Messing around with electricity, though, is not something that should be done by someone that has no clue. There are fire codes (incorporated in the National Electric Code) that could come into play should a fire or injury result. The insurance company could refuse to pay a claim if the NEC was not followed. A passed electrical inspection is the best insurance for a do-it-yourselfer. On these believes, I recommend educating yourself regarding electrical wiring and then ensuring your work is inspected by the county inspector. These inspections seem prudent to me should a fire or personal injury ever result; proof that the electrical work was done per code. In my experience in multiple jurisdictions, electrical inspectors are the do-it-yourselfer’s friend especially if you seem to know what you are doing.

You could read the National Electrical Code to educate yourself, but, having done so, I found this very laborious and mostly confusing since I am not a pro. The best resource I have found is “Wiring Simplified”. It is far better than any other book I have looked through and recommend it to you.

https://www.amazon.com/Wiring-Simplified-Based-National-Electrical/dp/099790531X

View Matt Przybylski's profile

Matt Przybylski

539 posts in 2213 days


#3 posted 03-09-2017 04:28 AM

JBrow, thank you for the response. I should have mentioned that I’m only running all of the conduit/wires in the conduit/boxes/leg work myself and am going to have an electrician come in and look everything over and do the connection to the panel. What I drew up here was what I thought I understood the electrician who came to give me an estimate (who was very nice and walked me through how I should wire it, although its kind of in one ear out the other type of thing until you sit down and experience it) said. I’m just verifying that I understood him correctly and hoping someone can clue me in if I made any mistakes.

I’m also sending this information to him as well as another neighbor who is an electrician back in Chicago, but I’m just looking to get as much input as possible from everyone I can. As you said, I don’t want to violate any codes.

Getting in touch with the city’s electrical inspector is a great idea that I did not consider. I can probably draw everything up, take it over to them, and hopefully they can give me some insight as to if I’m doing it right. Thanks for that tip!

-- Matt, Arizona, http://www.reintroducing.com

View TheFridge's profile

TheFridge

8298 posts in 1321 days


#4 posted 03-09-2017 04:56 AM

There isn’t any code I know that won’t allow the receptacles in the same box. Temporary power poles and generators do it.

The 20A 250V receptacles can’t be wired like that. Must be dedicated if another electrician is gonna put his name on it. Any 250V receptacle must be dedicated unless the feeder is size appropriately which just opens another can of worms and tap rules and whatnot.

No more than 10 receptacles on a 20A circuit.

In your garage or shop, all of your 15 or 20A receptacles must be GFCI protected. Putting a gfci receptacle at the start of the circuit and putting everything on the load side is the cheapest. Gfci breakers aren’t cheap.

Strap your pipe at least every 10’ and within 3’ of every box or accessible fitting.

Gotta have at least 6” of wire out the pipe or 2-3”? out of the box. Whichever is greater.

If any wire is spliced in a box then the box has to be grounded.

If you use stranded wire you don’t strip right at the end. You strip a 1/2” or so window about 2” from the end of the wire. It keep the end of the wire from fraying and keeps it insulated when tightening the terminal if landing on screws.

Rule of thumb- 9- #12s in a 1/2” and 16- #12s in a 3/4” pipe.

This is the basics an electrician will look for and by no means covers everything.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Matt Przybylski's profile

Matt Przybylski

539 posts in 2213 days


#5 posted 03-09-2017 05:00 AM

TheFridge, thank you for your input.

When you say they can’t be wired like that, why not? I will never use two machines at once on one 220 run.

As for 10 receptacles on a 20A circuit, is a duplex receptacle counted as two receptacles or one?

-- Matt, Arizona, http://www.reintroducing.com

View TheFridge's profile

TheFridge

8298 posts in 1321 days


#6 posted 03-09-2017 05:10 AM

But there is the possibility as far as code is concerned. Unless there is a control circuit that would lock the other out you can’t do it. My table saw and jointer is on the same circuit in mine but I didn’t need another electrician to look at it or an inspection.

One.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View TopamaxSurvivor's profile

TopamaxSurvivor

18088 posts in 3511 days


#7 posted 03-09-2017 06:00 AM

The 120 volt GFCI protected circuit needs to be in a separate conduit. GFCI and non GFCI circuits cannot be in the same conduit or enclousre.

Unless something changed in the last code update, you can have multiple 220 outlets on a circuit. I did it for a customer in an airplane hanger just before I retired. I don’t have a new code book and don’t want a new code book ;-) Another new code book is due out this year.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Matt Przybylski's profile

Matt Przybylski

539 posts in 2213 days


#8 posted 03-09-2017 06:11 AM

TopamaxSurvivor, I read this in multiple places: “GFI and non-GFI conductors can indeed occupy the same conduit or raceway. The restriction is only for underwater pool lights.”

-- Matt, Arizona, http://www.reintroducing.com

View tyvekboy's profile

tyvekboy

1701 posts in 2848 days


#9 posted 03-09-2017 04:04 PM

The only thing that I can add is that if you put multiple 220v outlets on one circuit, I wouldn’t run more than ONE 220 device off of that circuit at the SAME time. I have one 220v circuit that has (2) 220v outlets but I only run ONE 220 motor on that circuit at a time. I don’t know the code but I would rather have a separate circuit breaker for each 220v machine.

As far as the 20A – 120v duplex outlets I have quad outlets (4 in one box) spaced every 5-6 feet apart on the walls 42” from the floor. Every other quad outlet box is one one 20A circuit and the others are on another circuit. That way I can plug in many devices and they can be on different circuits depending on which outlet I plug them. I also put labels on my outlet boxes so I know which circuit breaker to which it is connected.

Another option someone suggested is to run multiple circuits and put outlets in one box on different circuits.

Another thing I did after I wired everything up I got a tester to check that the polarity was correct on each 120v outlet. The tester looks like:

I studded my shop and have plywood walls. Therefore I ran the romex behind the walls the mounted metal boxes on the walls where the romex came through a 1 inch hole. See my workshop tab for more details. If you don’t want to use conduit, you could also cut out a 1 foot section of sheet rock starting at 36” above the floor and ending 48” above the floor. Then you can run your romex behind the sheetrock like I did and mount your outlets on the 1/2 inch plywood that would replace the sheetrock that you cut out. Attach the plywood with sheetrock screws in case you want to reposition the outlets.

Hope this helps.

-- Tyvekboy -- Marietta, GA ………….. one can never be too organized

View Madmark2's profile

Madmark2

371 posts in 424 days


#10 posted 03-09-2017 06:13 PM

Put your outlets over 48” up to prevent sheet goods from covering them.

M

View TopamaxSurvivor's profile

TopamaxSurvivor

18088 posts in 3511 days


#11 posted 03-09-2017 06:42 PM


TopamaxSurvivor, I read this in multiple places: “GFI and non-GFI conductors can indeed occupy the same conduit or raceway. The restriction is only for underwater pool lights.”

- Matt Przybylski


Is that in the 2014 NEC? The restriction was fairly new before I retired.

Edit: I just Goggled that. The statements that popped up appear to be 10 years old. I believe the universal restriction came in 2008 or 2011 code. Glad I’m retired ;-) ;-)

I would be quite surprised is they relaxed that requirement. The electrical code just gets more and more strict. Multiple circuits on a common neutral are not allowed any more without common disconnect and they have to be identified with their hot conductor at each j box. That is a bigger burden on commercial and industrial that typical residential methods.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Fred Hargis's profile

Fred Hargis

4756 posts in 2329 days


#12 posted 03-09-2017 07:29 PM

Unless something changed in the last code update, you can have multiple 220 outlets on a circuit. I did it for a customer in an airplane hanger just before I retired. I don t have a new code book and don t want a new code book ;-) Another new code book is due out this year.

- TopamaxSurvivor


That’s my understanding as well, and what I have done in my last 2 shops and the current one (which I’m wiring now). I won’t have an inspection, but still try to stay to code. BTW, here's the wall plate for that240/120 configuration. You might want to bookmark it, they ain’t all that easily found.

-- Our village hasn't lost it's idiot, he was elected to congress.

View Roy Turbett's profile

Roy Turbett

137 posts in 3415 days


#13 posted 03-09-2017 07:34 PM

GFCI restrictions apply depending on whether the space is considered finished or unfinished and garages are generally considered unfinished space. What you are trying to do is run three strand wire to feed two circuits. This is commonly done on 120 volt outlets where a dishwasher and garbage disposal share the same box. In this instance there must be a bar that ties the two breakers together so that if one circuit trips the other will also trip and the entire box will be cold.

You can also use three strand wire to run 120v and 240v to the same box and even the same outlet. Leviton makes a combination outlet for this purpose. A 240v breaker controls both circuits and will render the box cold if either circuit causes it to trip.

https://www.googleadservices.com/pagead/aclk?sa=L&ai=DChcSEwi5u9fsjsrSAhWUuMAKHXGKDNcYABALGgJpbQ&ohost=www.google.com&cid=CAESIeD2WrvdGjT0fElnof4P2ZVwqonO_2Hjy8zi_xxBPRUs4Q&sig=AOD64_1DL5QTvn9HW7VQj2bmfSnELn18Tw&ctype=5&q=&ved=0ahUKEwj9rNLsjsrSAhXn1IMKHY0OAasQvhcILg&adurl=

I ran 10/3 romex for my 240v circuits when I built my shop so I could run multiple machines at the same time. I routinely had three 1 hp wood lathes running at the same time without a problem. Two of the lathes also had 120v duplex outlets on them so I could run a right angle sander and lights while running the lathe. I used a 20 amp breaker because the cords and connections for some of my 240 v tools are only rated for 20 amps even though the 10 gauge wire is rated for up to 30 amps, The 10/3 wire is extra insurance that I won’t have an overheating problem because it has less resistance than 12 gauge wire.

I pulled a permit when I built my shop in 1997 and did the wiring myself. Hope this helps.

View WhyMe's profile

WhyMe

910 posts in 1396 days


#14 posted 03-09-2017 08:36 PM

Your diagram is fine unless you have a local code prohibiting multiple 240V outlets on a single circuit. NEC doesn’t restrict multiple 240V outlets on a single circuit, but the IRC does limit multiple 120V/240V outlets on one circuit to 20A outlets. And where someone said no more than 10 outlets on a circuit is just a rule of thumb and is not set by the NEC.

View sawdustdad's profile

sawdustdad

334 posts in 720 days


#15 posted 03-09-2017 08:37 PM

I wired my new shop about a year ago. I ran 10/3 w/ground to all the 240V outlets (12 outlets on 6 circuits) and installed 4 wire twist lock outlets in every box. Most boxes had 30A receptacles, one was 20A. I did not share any boxes with 120V. I then created adapter cables to go from the 4 wire twist lock outlet to the appropriate female plug for each machine. Since many of my outlets are in the ceiling, the twist locks keep them from coming loose.

-- Murphy's Carpentry Corollary #3: Half of all boards cut to a specific length will be too short.

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