Wiring the shop

[Plumcrazy]

Greetings,
I am just beginning the demo phase of my workshop renovation. The shop has its own dedicated 200 amp service. Currently it has some lights a couple of 220v circuits (3) and 3 20 amp 110v circuits feeding maybe 9 outlets.
I plan on completly rewiring the in adequate lighting circuits, adding some more 110 circuits and some dedicated 220 circuits..
I know that the shop will need dedicated 220 circuits for,
Compressor 40 amps
Heater 30 amps
Welder 50 amps
There is a stong possibility that a milling machine and lathe will be purchased in the next year or two. The milling machine will probably be 220v the lathe could go either way. A media blast cabinet with vacum is also on the list.
The likelihood of several of these big consumers operating simultaneously is real. I could very easily see the compressor, heater, welder, blast cabinet and maybe even a handheld grinder all being operated at the same time, just not by me alone.
I was thinking of adding 8 additional outlets, wiring them with 12/3 wire. This would give me the future flexibility of wiring the outlet as a dual 110 or single 220. I am not certain what the future will bring but I want to avoid having to place a machine in a less than ideal spot or have to run extension cords , etc, etc. Does this sound reasonable? Anything else I should plan for? Any other tips?
Regards

 

[pattenp]

This is just my opinion but I would not run NM 12/3 wire thinking I may or may not use it as a MWBC for 120V outlets or possibly a 240V circuit. I'm a true believer of good planning and having 240V outlets being dedicated.

 

[Plumcrazy]

If I may ask, why not? I agree with the planning but if you don't know for certain what your going to be doing in there it's kind of hard. I know I need at least 1 50a 220 outlet for the welder. How many additional 220 outlet should I put in? How big should they be? Im going down to the studs so now is the time to do it.
Thanks

What is "MWBC"

 

[brewchief]

Running 12-3 NM wire would limit you to 20 amps on either a 120v or 240v circuit, helpful but not really future proofing.

Best way to future proof IMHO would be to run 3/4" or 1" EMT conduit to locations that you expect the equipment to go, when you have the equipment on hand you can pull the proper sized wire.

 

[pattenp]

Running 12-3 NM wire would limit you to 20 amps on either a 120v or 240v circuit, helpful but not really future proofing.

Best way to future proof IMHO would be to run 3/4" or 1" EMT conduit to locations that you expect the equipment to go, when you have the equipment on hand you can pull the proper sized wire.

I agree.

Here's another post... I did a search on "MWBC"
http://www.garagejournal.com/forum/showthread.php?t=272867&highlight=MWBC

 

[Charles (in GA)]

Please add you location (ie state,province, city) to your profile so we will have some idea of the climate you are located in, the country that we would be discussing electric codes for, etc.

Also, noting the size of your shop (including eave height, ceiling height), the type of construction, insulation, whether detached or attached to a residence, on its own meter of a sub off of the house, etc, would help greatly in the discussion.

Charles

 

[Charles (in GA)]

The code addresses MWBC in several ways, that are peculiar, and when installing them, you need to be aware of this.

210.4 Multiwire Branch Circuits.
(A) General. Branch circuits recognized by this article shall be permitted as multiwire circuits. A multiwire circuit shall be permitted to be considered as multiple circuits. All conductors of a multiwire branch circuit shall originate from the same panelboard or similar distribution equipment.

Informational Note: A 3-phase, 4-wire, wye-connected power
system used to supply power to nonlinear loads may necessitate
that the power system design allow for the possibility of
high harmonic currents on the neutral conductor.

(B) Disconnecting Means. Each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where
the branch circuit originates.

Informational Note: See 240.15(B) for information on the
use of single-pole circuit breakers as the disconnecting
means.

(C) Line-to-Neutral Loads. Multiwire branch circuits shall supply only line-to-neutral loads.

Exception No. 1: A multiwire branch circuit that supplies only one utilization equipment.
Exception No. 2: Where all ungrounded conductors of the multiwire branch circuit are opened simultaneously by the branch-circuit overcurrent device.

Informational Note: See 300.13(B) for continuity of grounded conductor on multiwire circuits.
(D) Grouping. The ungrounded and grounded circuit conductors of each multiwire branch circuit shall be grouped by cable ties or similar means in at least one location within the panelboard or other point of origination.
Exception: The requirement for grouping shall not apply if the circuit enters from a cable or raceway unique to the circuit that makes the grouping obvious.

240.15 Ungrounded Conductors.
(B) Circuit Breaker as Overcurrent Device. Circuit breakers shall open all ungrounded conductors of the circuit both manually and automatically unless otherwise permitted in
240.15(B)(1), (B)(2), (B)(3), and (B)(4).
(1) Multiwire Branch Circuits. Individual single-pole circuit breakers, with identified handle ties, shall be permitted as the protection for each ungrounded conductor of multiwire branch circuits that serve only single-phase line-to neutral loads.

300.13 Mechanical and Electrical Continuity — Conductors.
(B) Device Removal. In multiwire branch circuits, the continuity of a grounded conductor shall not depend on device connections such as lampholders, receptacles, and
so forth, where the removal of such devices would interrupt the continuity.

As they say, "the devil is in the details".

Personally, I highly recommend staying away from MWBC unless there is a specific and functional need for them. I installed MWBC for my lighting, using three DP breakers and DP snap switches, and receptacles with the hot side (brass.. narrow blade) tab broken out. The receptacles are installed next to the Metal Halide lights they power and allow for some rather unique lighting configurations.

MWBC cause all kinds of GFCI issues unless you are planning on installing GFCI receptacles at each outlet position. If you don't do this, you end up splitting the MWBC into two separate runs with their own neutrals at the point where the GFCI recpeptacles are installed, as their downstream loads cannot share the neutral past the GFCi receptacles. GFCI DP breakers also have issues with MWBC and its just not worth the hassles.

As mentioned, 240v circuits are rather unique in their demands and it is usually best to simply run dedicated circuits for this.

In some states or locations, multiple 240v receptacles are not allowed on one circuit anyhow. (this is, in part, why we need to know more or less where you are located). Some places may not allow MWBC for general use either.

Charles

 

[olytdi]

Nothing beats excellent layout planning. If you know where your equipment is to be used, you know where to install the associated receptacles. Hanging conduit would provide the greatest options for reconfiguring if needed.

I would think that welders would constitute the equipment most likely to need movement about the shop. As such, I mounted my two 50A welding receptacles at opposite sides of the building and have extension cords to accommodate welding outside/inside...where ever. Presumably your heater and compressor will be fixed in location? That would leave basically your mill and lathe. Can you plan-out a permanent location for these as well??

 

[Plumcrazy]

I live in Perkasie PA. The shop is 38'x20'. Block foundation, stick frame. Reno plans are for drywall walls and ceiling with as much insulation as I can fit. , 6" at least.
It's a detached building on my property. It has its own 200a service, in other words I get 2 electric bills.
Most of my projects currently are automotive related but who knows, ten years from now my passion may be with cabinet making. It's really a great space that up until now was always partitioned off and broken up strangely. This Reno is going to leave the space wide open, painted, properly lit, and hopefully properly powered for a serious home shop, whatever that may bring
Cheers

 

[olytdi]

Small world, Plum. I lived in upper Bucks County for 10 years prior to my move out west.

Sounds like a fun project!

 

[CNGsaves]

So much easier to plan ahead and make those decisions now while walls are wide-open to studs. Guessing and putting off hard decisions until later, will lead to work-a-rounds (ie a mix of in-wall wiring, and later surface mount conduit if you didn't plan ahead).

+1 to put in multiple conduits (even if to empty box, except for pull rope) for only those truly unknowns in future (ie lathe not bought yet, etc). However, pre-wire the known equipment in-wall with dedicated runs and "overwire" with higher capacity gauge wire to allow flexibility.

Recommend using SketchUp software which if FREE that many GJer's have used to dream up how shop would be finished and where equipment would go.

Alternatively, could go simple "musical chairs" with paper drawing of shop layout to scale and have paper cutouts of equipment to scale and move around in different scenarios that you think will match how you use the shop. The extra welder plug near outside garage door is an example of that scenario.

 

[dfiler2]

I have gone through the same decision making process recently. I tried to draw out and plan for every scenario I could think of, the right number of outlets, outlets in the ceiling, future tool upgrades, do I want cat-5 run to both far corners etc..etc.....I started talking to people who had built shops in the past few years and the one thing that was mentioned over and over was surface mount EMT for electrical. They are able to make changes easily , and most have made a few changes after getting into and using their shop. It allows for future changes of tools and location of tools. I am just working on getting the walls covered and then will start the wiring. Just working in the building now has me changing my mind about the location of some outlets. Plus now I will not be held up by the electical inspection. Might be something you want to consider.

 

[C96]

I have gone through the same decision making process recently. I tried to draw out and plan for every scenario I could think of, the right number of outlets, outlets in the ceiling, future tool upgrades, do I want cat-5 run to both far corners etc..etc.....I started talking to people who had built shops in the past few years and the one thing that was mentioned over and over was surface mount EMT for electrical. They are able to make changes easily , and most have made a few changes after getting into and using their shop. It allows for future changes of tools and location of tools. I am just working on getting the walls covered and then will start the wiring. Just working in the building now has me changing my mind about the location of some outlets. Plus now I will not be held up by the electical inspection. Might be something you want to consider.

↑↑ I totally agree with this ↑↑

It’s virtually impossible to plan for equipment you don’t even know you want or need yet. As soon as you get something new or just decide to rearrange things the entire layout becomes pretty much a waste. You end up with extension cords or exposed conduit on the walls anyway.

The EMT gives you the option to expand and or rearrange outlets without a great deal of trouble.

I personally like the look of exposed EMT in a shop environment, but then I also like exposed black pipe for compressed air lines too.

 

[1Garageman]

↑↑ I totally agree with this ↑↑
I personally like the look of exposed EMT in a shop environment, but then I also like exposed black pipe for compressed air lines too.

Me to! It adds character to the room, but also helps you trace lines, see where they lead to, and much easier to fix if something happens to the line, or pipe!

 

[Plumcrazy]

Greetings,
Thanks for the replies. Definitely gave me something to think about. I like the idea of EMT but at this point I'm not going to install any. The plan is to install 2 50a 220 lines diagonally opposite in the shop. I'll then add 5 maybe 6 dedicated 30a 220 circuits. Most machines power cords are 10 ft or so in length so I should be able to reach an outlet without too much compromise.
Thanks again

 

[conceptmachine]

I'm building a machine shop right now. I'm going to have ceiling outlets so i don't have cords laying all over the place like I do in my current shop. Might want to look into that.

 

[CNGsaves]

I'm building a machine shop right now. I'm going to have ceiling outlets so i don't have cords laying all over the place like I do in my current shop. Might want to look into that.

^ ^ That is creative "thinking outside the box" along with some shops that are so dedicated to their function that floor mount electrical boxes might be considered.

Planning ahead is tough but sounds like OP has a gameplan. Good luck.

 

[RickP]

I live in Perkasie PA. The shop is 38'x20'. Block foundation, stick frame. Reno plans are for drywall walls and ceiling with as much insulation as I can fit. , 6" at least.
It's a detached building on my property. It has its own 200a service, in other words I get 2 electric bills.
Most of my projects currently are automotive related but who knows, ten years from now my passion may be with cabinet making. It's really a great space that up until now was always partitioned off and broken up strangely. This Reno is going to leave the space wide open, painted, properly lit, and hopefully properly powered for a serious home shop, whatever that may bring
Cheers

That sounds like a great shop - congratulations on tackling the full reno and doing it right! I like your idea of several 220v outlets around the shop - it doesn't cost that much and adds flexibility.

How are you running your compressed air lines? I like black pipe, but I also have one line that I wanted to run behind the drywall, so I used a RapidAir kit. It makes for a nice clean installation. $78 on Amazon

 

[FrankTheTank88]

Strated reading thru this but just my advise, mount the pannel in a way you can bring more runs of surface mounted EMT back out of it so you can add receps 120/240v where and when you need them. If it is flush mounted, mount some surface 1900 boxes which wire ways into the pannel that you can brake out of at a later date with EMT

 

[Plumcrazy]

Thanks again for all the replies. I've got the demo done and I'm down to the studs. One thing I never budget enough time for is debris removal. When your working alone man you spend a lot of time just getting rid of the old. I'm worn out!
Anyway as much as I like the functional idea of surface mounted conduit I'm reall looking for a clean install. I want everything to be "bright and white" the only thing I'm going to surface mount will be the air lines. I'm only planning on three drops so it shouldn't be too noticeable.
In the interest of a clean install is there any reason I can't plug my compressor, heater and what not in as opposed to "hardwiring". I thinking if I can plug a welder in, why not? If I bought factory made 50 amp "stove" cords would I be violating any codes?, any machine operating deficiencies I'm not aware of?

 

[brewchief]

Thanks again for all the replies. I've got the demo done and I'm down to the studs. One thing I never budget enough time for is debris removal. When your working alone man you spend a lot of time just getting rid of the old. I'm worn out!
Anyway as much as I like the functional idea of surface mounted conduit I'm really looking for a clean install. I want everything to be "bright and white" the only thing I'm going to surface mount will be the air lines. I'm only planning on three drops so it shouldn't be too noticeable.
In the interest of a clean install is there any reason I can't plug my compressor, heater and what not in as opposed to "hardwiring". I thinking if I can plug a welder in, why not? If I bought factory made 50 amp "stove" cords would I be violating any codes?, any machine operating deficiencies I'm not aware of?

There is a horsepower limit on plug and receptacles that may require you to hardwire the compressor.


You can run conduit behind the drywall, if you have unused runs just put a blank cover on the box until you need it.

 

[Rennkafer]

I'm at the same stage as the OP in that I have to do sheetrock, wiring, and air lines in my shop. I'd already thought to do the wiring surface mounted in conduit, but it seems like that would entail doing the air piping first and then bending the conduit over it (which seems like a huge pain).

How have you guys handled this?