Conduits, circuits, and outlets.

[Rick Moyer]

Which way would you do this?
I plan to install about 8-12 duplex 110 outlets and about 4 or so 220 single outlets in the new shop. All wiring run in 3/4" EMT, surface mounted, and along two adjoining walls. I know that I can run up to three circuits in the conduit (12 ga. /20a.).
A. If I run all the wiring from three circuits (110 and 220) I can run one line of EMT plus j-boxes for drops. This however would only allow me to have 2 110 circuits and all four or so 220 would be on one circuit.
B. But if I choose to split receptacles or to seperate boxes into more circuits, I will have to run twice as much conduit in order to have more circuits.
I am leaning toward more circuits as I have a >1/2-empty 100a. panel box, but am concerned about the EMT clutter, especially having to leapfrog the conduit in places (I don't want to buy a bender and learn to use it if I don't have to), and also the extra expense. I suspect I would run three 110's in one conduit and 2 or 3 220's in another conduit. Would you go to the trouble of running extra circuits or would you save the trouble and expense and run 2-110's and one 220 in one run of conduit?


I should note that the DC will have it's own circuit and breaker. I am a one-man shop so nothing running simultaneously except with the DC. Lighting is already installed on two seperate breakers, so that's not a factor. Only 220 tool right now is the jointer (besides the DC), but would like to have 220 TS and maybe 220 BS in the future, but again only one runing at one time.

Another question: If I were to run all three circuits in one run, can I use any color wire for the 220 hots? I would like to use blk/wht for the 110's, then maybe red/blue for the 220 hots, along with green for the ground. If I use only one ground for all three, will 12ga. be OK or does it have to be larger wire?

[Scott T Smith]

If it were me, I'd either run two conduits or upsize my single conduit to adequately carry the extra circuits.

[Rod Sheridan]

Rick, if you're a one man shop where only one machine is running at one time, you only need one circuit.

You can use a 2 pole 15 or 2 pole 20 Ampere breaker to feed all your 120V and 240V receptacles.

The 120 V receptacles can be wired as an Edison or split circuit to yield 2 circuits for 120V and 1 circuit for 240V.

You would only need 3 conductors plus ground, so 1/2" EMT may fit the bill.

Regards, Rod.

[Rob Russell]

Rick,

One factor that will impact how you can wire the shop is WHERE the shop is located.

Is your shop in either a garage, unfinished basement or grade level standalone shop?

• If the answer is "Yes", then your 120v circuits must be GFCI-protected.
• If your shop is an "accessory" building and the floor is "at or below grade level" and its use is as a "work area", then the 120v circuits must be GFCI-protected.

[Von Bickley]

Rick,

One factor that will impact how you can wire the shop is WHERE the shop is located.

Is your shop in either a garage, unfinished basement or grade level standalone shop?

• If the answer is "Yes", then your 120v circuits must be GFCI-protected.
• If your shop is an "accessory" building and the floor is "at or below grade level" and its use is as a "work area", then the 120v circuits must be GFCI-protected.

Again this depends on where you live and the local inspection department. In my area, the receptacles DO NOT have to be GFCI if that area is designated for woodworking and woodworking equipment. Talk with your local inspector.

[Craig Moulton]

I'm sure you know some of this stuff, but better too much info...

You can double the number of circuits by running the 3/4" EMT both ways from your P-Panel to the loads, two branches of pipe each containing half your circuits, rather than one big loop. If needed, you can use flex cable between junction boxes. Easier than learning to bend conduit, trust me. Just make sure that any wire-nutted connections you have to make have a good mechanical and electrical connection. Twist the wires together well before putting the wire nut on them. The wire nut's job is insurance and insulation, not your main connection.

By code, 12 GA or larger for 20A service (regardless of voltage), 14GA for 15A (Lights etc) string. The overcurrent protection amperage size is to prevent the wires from overheating due to resistive heating based on current draw.

Use individual wires (not romex) inside EMT. Heat dissipation is the concern here, from extra layers of insulation between the copper and the air. Stranded wire is easier to pull than solid copper, but harder to push. Use pulling elbows at some corners to make your job easier. I use pieces of masking tape at the end of wires to indicate circuits when pulling them. You could also use one piece of black tape for ckt 1, two pieces for ckt 2, etc.

Typically for 110V service, wires are black / white / green or bare.

Typically for 220V service, wires are black / red (or black) / white / green (or bare) if a neutral is used, Black / red (or black) / green (or bare) if no neutral is used. Using non-standard colors may create confusion later.

Black wires have 110V to ground and neutral (white). So do red, or the other leg of 220V service, whatever you color it. The only real problem as far as wire colors, is when people use white wire for one leg of 220V and don't mark it at the ends, and later someone tries to use it for a 110V circuit. This causes fires, shocks, burnt out equipment, other badness. If you have to use white wire for some reason, mark the wire at every connection point with a piece of red electrical tape wrapped around the wire.

Your number of circuits depends on their loading, and how often they will be running. If you have your table saw, planer and jointer on one circuit, but only ever use one machine at a time, this works well. Air conditioners draw large starting currents, and start their compressors at irregular intervals, so shouldn't be on shared circuits. I try to think about all the things that will never be running simultaneously and tie them together to free up other circuit choices, then go from there.

Put a GFCI on any circuit that you will have a portable tool plugged into. Or might ever plug one into. Or might ever think of plugging one into. This includes vacuum cleaners, etc. I recommend a GFCI breaker rather than individual outlets, much cheaper. OSHA requires use of a GFCI with portable tools, and is the best practice for a shop even if not required by local codes.

Size ground wire the same as the rest of the wires in the circuit. It doesn't normally carry current, that's the purpose of the neutral wire. Neutral and ground wires are the same electrically, except that neutral is the return path in 110V circuits (or the 110V portion of 220V circuits) and ground is there to prevent you from getting shocked in the event of an electrical ground fault.

[Rick Moyer]

If it were me, I'd either run two conduits or upsize my single conduit to adequately carry the extra circuits.

Thank you for answering my question

Rick, if you're a one man shop where only one machine is running at one time, you only need one circuit.

You can use a 2 pole 15 or 2 pole 20 Ampere breaker to feed all your 120V and 240V receptacles.

The 120 V receptacles can be wired as an Edison or split circuit to yield 2 circuits for 120V and 1 circuit for 240V.

You would only need 3 conductors plus ground, so 1/2" EMT may fit the bill.

Regards, Rod.

I understand that. I was thinking it may be better to add more circuits "just in case" things change. Maybe I am overdoing it however. I will consider your idea.

I'm sure you know some of this stuff, but better too much info...

Typically for 110V service, wires are black / white / green or bare.

Typically for 220V service, wires are black / red (or black) / white / green (or bare) if a neutral is used, Black / red (or black) / green (or bare) if no neutral is used. Using non-standard colors may create confusion later.


Your number of circuits depends on their loading, and how often they will be running. If you have your table saw, planer and jointer on one circuit, but only ever use one machine at a time, this works well. Air conditioners draw large starting currents, and start their compressors at irregular intervals, so shouldn't be on shared circuits. I try to think about all the things that will never be running simultaneously and tie them together to free up other circuit choices, then go from there.

Size ground wire the same as the rest of the wires in the circuit.

Thanks Craig. I DO know must of what you posted but as you said, better too much than...
"Using non-standard colors may create confusion later". I know the typical colors, but I figured having several blacks would be more confusing than having for instance, a red and blue for the 220 hots, and the black(s) be for 110 only. Would you think this would be a bad idea?

"I try to think about all the things that will never be running simultaneously and tie them together to free up other circuit choices, then go from there." That's easy for now as I said I am a one-man situation. I was thinking that if something changed down-the-road, which would be best. I have a lot of spaces in a 100a panel box, just not sure how much wire and conduit I want to run.

"Size ground wire the same as the rest of the wires in the circuit"
Thank You. This was something I was not sure about.


To All; I guess I was asking if it would be a good or bad idea to run red/blue for the 220 hots or keep the one hot always black along with the 110's, and whether YOU would add several circuits or go minimal for the sake of ease and expense. I'm leaning toward extra circuits I think but would like others opinions as well.

[Joe Jensen]

I used to have one 220 circuit as I am a one man shop. Then I got an air compressor that will come on when it wants (need 2nd circuit). Then came a 2HP dust collector (need 3rd circuit). Then I added a mini split AC (now need 4 circuits).

If I were starting again, I'd spend the extra and do additional circuits for future flexibility. I also had to rewire when I upgraded from a 3HP to a 5HP table saw. I didn't think of that detail until I was unpacking the saw. Needed to run larger wire and a new breaker.

[Scott T Smith]

Rick, you pose some good questions, and I'll toss out some extra thoughts for consideration.

First, I like your idea regarding the color separation for your 120 versus 240 circuits. By all means use red and blue for your two hots on your 240, and black for the hot on your 120.

Something that I do in my boxes and at my load center is - where the wires enter the box - to put a cable tie or piece of tape around wires that are associated together. Thus, if I'm using multiple black wires for my various circuits, one of them will have red tape around it denoting the second leg, and both will be taped together indicating that they are a paired circuit. Same thing with a black and white - makes it easier to troubleshoot long term.

I recently built a new shop, and wanted to install an electrical infrastructure that would be flexible enough so that I could run additional circuits in the future without having to redo everything. Sure, I know what equipment that I have today, but who knows what cool thing I may stumble across in the future?

I opted to install several runs of 3" conduit infrastructure through my slab, and terminate these into 6" junction boxes in various locations along my walls. From the junction boxes, I run either 1" or 1-1/4" conduit to 4" electrical boxes spaced along the walls.

Each 4" box has two 120V receptacles in it, fed from two different breakers (and two different legs of the service). So, at any time, if I need a 20A 240 circuit in the shop, I only have to do two things: First - replace the two 120V receptacles with a 240 receptacle (I use NEMA L6-20's), and second - swap out the appropriate single pole breakers in the load center for a dual pole 240 breaker. Voila - 240 availability with no rewiring.

In the event that I don't need 240, I still have two separate 20A 120 circuits available at every receptacle location, so I can operate two larger pieces of equipment simultaneously if needed.

If I need a 30A 240 service, then I'll pull two new 10 ga wires for the larger service. I typically leave a pull string in place in my conduits for ease of future wiring.

All of the 6" junction boxes have #8 green ground wire pulled to them, which I can branch off of for individual grounds in the appropriate receptacles along that wall.

So I think that the most important thing for you to consider is to install a conduit infrastructure that will allow you flexibility longer term, because if you need a larger 240V circuit you will need to pull larger wiring. Conduit is fairly cheap - wiring is not, so by investing in the conduit up front you are providing yourself with a lot of long term flexibility without dedicating $ to wiring that you might not need?

If you do any ceiling drops, then consider using NEMA L14-20 and L14-30 twist-loc receptacles. The nice thing about these is that you can use them for either 120 or 240 wiring, so a single receptacle can serve both purposes.

One other thing - stranded wire is usually the best option through conduit, as opposed to solid. It pulls easier and carries more current.

Hope this helps - good luck with your project.

Scott

[Dennis Ford]

You can avoid leapfrogging the conduit by using J-boxes that have two openings in each side and a single opening in the bottom. This will allow two parallel runs of 3/4" conduit that share J-boxes.

[Bruce Wrenn]

If you are use EMT, you shouldn't have to pull a separate ground wire. But you will need to bond recpts. with a ground wire to boxes. Here, inspectors generally only require GFCI closest to outside doors. So I use multiwire branch circuits.

[Rick Moyer]

Scott, again thanks for the info. Very insightful.

Dennis, that sounds great, but I am wondering about the allowable current carrying wires in a given j-box for multiple circuits. I know I am allowed 6 current carrying wires in the 3/4 conduit but not sure if this correlates directly with the boxes? If I went with two conduit runs into a j-box, each conduit containing two circuits (4 current carrying wires ea.) would this be allowable or too much? I suspect the j-box would only be allowed the same as a given conduit (i.e. 6ccw's).

[Bill Stoffels]

As previous stated have more circuts than less. I built my first shop and added circuts, then here at my second shop just doubled the plans and to date 5 years later its working well.
Just a suggestion?
Bill

[Rick Moyer]

OK, here's what I think I will do:

Run two separate conduit runs; one for 240, one for 120.
Each conduit run will contain three circuits

This will accomplish several things:
1. allow me to have plenty of circuits
2. separate the 120 and 240 lines to avoid confusion
3. make it a little easier to add-on later if needed

I could run it all in one conduit (three circuits) and be fine but that will limit me to only one circuit of either 120 or 240. Since the DC should have it's own 240, I would only be able to have one 120 circuit then (plus one for the DC and one for the other 240 outlets).

Questions? Will it be better to use GFCI breakers in the panel box , or use GFCI receptacles in the first position of the circuits? Also, will I need to pull a ground wire throught the EMT or can I just attach a "bond" wire from the boxes to the recepts?

[David Parker]

Hi Rick,

A lot of great advice on this thread. Having recently wired my basement shop, I found that box size was a limiting factor in the number of circuits I could run. I didn't want huge surface mounted boxes on my cement walls. I limited them to 4x4 1 1/2" deep drawn metal boxes (as apposed to welded boxes). Fill capacity calculations limited the number of wires I could bring into or through any box. You can get a little extra capacity using the raised Garvin style box covers. I wanted to use a separate horizontal run of 3/4 conduit with interspersed boxes on each of my two adjacent cement walls about 52" above the floor (sub-panel near the corner). This let me keep the bottom of the boxes above 48" and also kept the walls above the boxes clear of any conduit drops. This gives a nice clean appearance and keeps the upper wall space clear for future cabinets/shelves/whatever.

I placed a 20amp 240V twist-lock outlet in the first box (using 10g wire so I could easily upgrade breaker and outlet to 30 amp if needed in the future). An adjacent box has a duplex 20amp GFCI outlet on a separate 12g circuit that then feeds two other outlet boxes further down the horizontal conduit run. The GFCI outlets are a lot cheaper than GFCI breakers. My adjacent wall is similarly configured but with separate circuits. My thinking is that if I have two heavy amp devices running at the same time, I'll just make sure they are on different walls. I do have a separate circuit for my 120V dust collecter. I also have outlets on my other two stud walls that are fed via additional circuits run with Romex through overhead joists.

Also, I would definitely run a separate ground wire and not rely on the metal conduit for your ground. Although the metal conduit ground is within code, all the electricians posts I've read on the electrical forums recommend running a separate ground wire. It's easy and inexpensive.