Shop power - conduit & boxes or flush outlets and Romex?

[PNWguy]

I'm trying to decide between surface mount (conduit and boxes) vs flush mounted boxes with Romex in the walls when I build my new shop.

Flush mounted boxes and Romex seems cleaner, but surface mount & conduit would be so much easier to make changes to later.

Any opinions?

 

[Chilliwack Murray]

Depends on how you plan to finish the walls. If you put plywood or OSBs on with screws, it's no more work to make changes later.

Conduit on the surface will cost more up front and is more work. I really don't like having something to get in the way later of putting something against the wall or that can get knocked off or damaged.

Just my 2 cents canadian, so worth slightly less down there.

 

[Stuart in MN]

Also depends on how well you plan things now so you don't have to make changes later.

 

[PNWguy]

Depends on how you plan to finish the walls. If you put plywood or OSBs on with screws, it's no more work to make changes later.

Conduit on the surface will cost more up front and is more work. I really don't like having something to get in the way later of putting something against the wall or that can get knocked off or damaged.

Just my 2 cents canadian, so worth slightly less down there.

I'll probably use sheetrock, but will get a quote for OSB as well. I plan to put the bottom of the outlets at 4' 2", so sheetgoods can lean against the wall and not block the outlets (although there will be sheetgood storage under the stairs).

The 120v will be easy - every 6' or so. But the 240 will be harder to correctly guess the first time. Pay now or pay later...

 

[larry_g]

I have both. Lights and 120v is mostly in the walls, Romex. 240v and 3 phase are in conduit and easily moved, added, or changed as equipment set changes or moves.

lg
no neat sig line

 

[Kevin C]

I did conduit with flush mount. I ran 3/4" in a loops along the top of the walls and put a junction box at each drop. I spaced the sheetrock from the studs using 2" XPS foam.

That way never see the conduit, but I can still fish new wires to any outlet. Sheetrock fully supported on foam is pretty tough. I put it up with a combination of adhesive and long sheetrock screws. The foam is adhered and screwed to the studs, same with the sheetrock.

The stud bays have R13 fiberglass. I spent a bit on foam, conduit was cheap since it was a DIY. Notching the foam to fit over the conduit was a pain.

While it was a lot of work, being able to add in switched outlets and or add 240 volts sockets as needed has been great. The super insulation has worked out well, the shop is very easy to heat.

 

[ard]

I did conduit (actually EMT) inside the walls. Insulation and sheetrock. Flush plates.

If I need to add, I can pop on a 4" extension ring and add onto the surface. Havent needed to in 15 years.

 

[pjmariner]

I did a hybrid approach.

I did surface mounted boxes with romex. Part of the reason is I did not have space behind the wall sheeting to use the boxes I wanted, the sheeting is on face mounted 2x3, so there is only 1.5 inches between concrete walls and sheeting.

The main benefit is i can add new outlets/make changes using conduit very easily. I ran all the romex before hanging sheeting, and I put outlet everywhere I thought I needed them. If I decide to make changes later, I will add additional outlets using conduit. since the boxes are surface mounted I can just run conduit from nearest box to desired location.

I ran 2 circuits using 12/3 romex to each box, so I have separate 20 amp circuits at each location

you can see build here.
https://www.garagejournal.com/forum/showthread.php?t=397592&referrerid=358853

B83C9475-EA67-416A-93D4-2D8E61106D1B by https://www.flickr.com/photos/120925262@N04/, on Flickr

 

[Falcon67]

I used a bit of both. Just depends on your layout and how you plan to use the space.

 

[Radix2]

If you put in a ton of outlets - it is extremely unlikely that there will be any changes.

It is still cheaper faster and easier to put in extra Romex now than to put in conduit, I put in double gang boxes every 4-6 feet, every box can have either 120 or 240 20A outlets. Run some extra higher current runs if you think they are possible. 6,8,10 gauge Romex is still cheap compared to doing a bunch of conduit prep for it.

Worst come to worst, do as above and come out of the wall for the late additions.

 

[finn]

Romex in my garage at home, and conduit in my shop.

I prefer the conduit, surface mounted.

 

[PNWguy]

Thanks for all the great answers.

Radix2 - the 120 is easy, and I'll probably do something like you did with a double gang box every 6'. Knowing where all the 240 should go is a bit more difficult. Perhaps I'll just put one next to every other 120 box.

 

[nadogail]

For the shop I built for a tenant in a rental house, I used surface mounted PVC.

Quick, Cheap & Easy.

 

[PNWguy]

I did a hybrid approach.

I ran 2 circuits using 12/3 romex to each box, so I have separate 20 amp circuits at each location

you can see build here.
https://www.garagejournal.com/forum/showthread.php?t=397592&referrerid=358853

PJ - nice work on turning a fairly bad spot into a good shop.
I'm confused about how you wired the double gang boxes. Is it normal to share a neutral between two circuits? I'm not an electrician, but something tells me that sharing a neutral would overload the wire if you were running a high amp load on both circuits.

I had double gang boxes with two circuits in my last shop, for the same reason you do. I'm also one of those OCD guys who couldn't handle the color change, so I made the left side the same circuit on every box, and the right side the other circuit. I did it with two runs of 12-2. That shop was much smaller, and copper was cheaper. Since my new place will be much larger, the idea of running 12-3 like you did is appealing

 

[Milton Shaw]

In my 28x32 shop I ran 3/4 EMT to the center of each wall and put 4x4 boxes with two 120 volt circuits and double GCFI's in that box feeding outlets to either side of the box, about every 36" down the walls. That way the tripped GCFI is not more than about 15 feet away. Additional EMT was run for 240 outlets on each wall. Walls were then insulated and sheet rock added. This was nearly 30 years ago now and I have had to run only one additional EMT since then to connect Light circuit to motorized valve on compressor outlet to switch air with light switch. Air and whole house vacuum outlets were also added behind sheet rock, I do have 4" PVC for dust collection down one wall and under floor for woodworking hobby.

 

[Kaizen]

I will be utilizing every square inch of my walls for either cabinets or hanging stuff so i'm putting up AC plywood where i can screw anywhere i want. I'm also sure that i won't get my layout right the first time so i want to be able to have flexibilty in the future. So i'm going all external emt with surface mount boxes. I will most likely run the main trunks up at about ceiling height and then drop down to outlets. An unplanned side affect was i could insulate and sheath the intoior walls and put up cabinets without needing to do the electrical inspection. This is giving me the ability to use my shop with extension cords and some insight into what works and what doesn't. Only thing i've found can be an issue is drops of emt in a bank of cabinets.

 

[Radix2]

PJ - nice work on turning a fairly bad spot into a good shop.
I'm confused about how you wired the double gang boxes. Is it normal to share a neutral between two circuits? I'm not an electrician, but something tells me that sharing a neutral would overload the wire if you were running a high amp load on both circuits.

I had double gang boxes with two circuits in my last shop, for the same reason you do. I'm also one of those OCD guys who couldn't handle the color change, so I made the left side the same circuit on every box, and the right side the other circuit. I did it with two runs of 12-2. That shop was much smaller, and copper was cheaper. Since my new place will be much larger, the idea of running 12-3 like you did is appealing

When you share a neutral it is called a multi wire branch circuit - mwbc. You feed the circuit with a two pole breaker, since the two 120v circuits are out of phase, if you where to actually pull full current on both circuits at the same time, the neutral current would be zero! ( the neutral carries only the difference between the phases). By running a mwbc, at each box you can have either of two 120v circuits, or a 240v circuit. This is how I ran mine as well, gives maximum flexibility at each box. If you by 240v duplex outlets, you can even use normal wallplates.

On caveat is you need to use gfci outlets at every 120v position unless you complicate the wiring more. Or expensive double pole gfci breakers.

 

[Crazyjake8493]

I prefer surface mounted conduit and boxes for two reasons. One, you can get a better sealed building envelope without holes in the wall for boxes. And two, it’s easy to add or change things down the road as you get more tools or equipment.

 

[pjmariner]

On caveat is you need to use gfci outlets at every 120v position unless you complicate the wiring more. Or expensive double pole gfci breakers.

I used a GFCI dual pole breaker, was about $90 for my panel, but then i was able to use contractor packs for all the outlets, which cost next to nothing.

 

[Kaizen]

.



On caveat is you need to use gfci outlets at every 120v position unless you complicate the wiring more. Or expensive double pole gfci breakers.

Gfci required because of the shared neutral or cause it’s a garage? Can’t put one and have all downstream protected?


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[Radix2]

Gfci required because of the shared neutral or cause it’s a garage? Can’t put one and have all downstream protected?


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Not related to shared neutral - general code req.

If you want to simply run 12-3 down the wall, you cant protect downstream outlets.

Of course you can still do the downstream if you create the protected circuit with a run of 12-2 from there, but then you need to do the other phase, and can't run 240 off of those feeds, so if you want that, more wire.

hence my comment - there are two simple ways to do the MWBC - either use a GFCI breaker, or use GFCI outlets. - then all you need is 12-3 down the wall and can get 2 different 120v circuits or 240v at any position

(I actually did the complext method using wiring and few GFCI outlets, but I am more comfotable with the wiring complexity than most would be.)

 

[PNWguy]

When you share a neutral it is called a multi wire branch circuit - mwbc. You feed the circuit with a two pole breaker, since the two 120v circuits are out of phase, if you where to actually pull full current on both circuits at the same time, the neutral current would be zero! ( the neutral carries only the difference between the phases). By running a mwbc, at each box you can have either of two 120v circuits, or a 240v circuit. This is how I ran mine as well, gives maximum flexibility at each box. If you by 240v duplex outlets, you can even use normal wallplates.

On caveat is you need to use gfci outlets at every 120v position unless you complicate the wiring more. Or expensive double pole gfci breakers.

Radix2 - thanks for the detailed answer. I had no idea.

 

[TractorJeff]

I thought you couldn't use a shared neutral anymore?
I thought I read that somewhere?

 

[Bert_]

I thought you couldn't use a shared neutral anymore?
I thought I read that somewhere?

It's fine and legal, it just has more complications then it used to. Handle tied breakers is one and it can be complicated in situations that require gfci. What you can do in that situation is multi wire to the first outlet then run separate neutrals from there. Anymore it only makes sense where there is a long run to the set of outlets / load.

 

[Norcal]

The first thing with garages is that GFCI protection is required for all 15A, & 20A, 120V, receptacles, if 12/3 NM or any other type of multiwire circuit is used then it gets trickier, either a 2-pole GFCI circuit breaker has to be used, or GFCI receptacles at every location, use a multi-wire feed to the first outlet install GFCI receptacles & keeping downstream hots & neutrals separate from the 2.

 

[7635tools]

What’s wrong with conduit in the walls? Romex is garbage in my opinion. Glorified extension cord in the walls. Conduit is better in every way. It’s not that much more to do it. You’ll be glad you did when it’s time to add/change things later.


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[Norcal]

What’s wrong with conduit in the walls? Romex is garbage in my opinion. Glorified extension cord in the walls. Conduit is better in every way. It’s not that much more to do it. You’ll be glad you did when it’s time to add/change things later.


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That is my preferred way, but a little planning should mean that changes are not necessary.

 

[rd65]

I just finished my electrical in a pole building. I ran romex in attic to junction box where it turned to thhn in conduit. Walls are plywood (not much more $ than osb). 2 20amp outlet circuits. Tamper resistant outlets-code w/ GFCI breakers. My layout is basic, ez conduit work. I've never done electrical and it seems to have worked out.

 

[Kaizen]

What’s wrong with conduit in the walls? Romex is garbage in my opinion. Glorified extension cord in the walls. Conduit is better in every way. It’s not that much more to do it. You’ll be glad you did when it’s time to add/change things later.


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Running horizontal is a pain and unnecessary labor expense. If you are laying block or concrete wall then ya.


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[Stuart in MN]

I'm curious how many people actually make a lot of changes after the initial install...if you plan it out right I would be surprised if you have to.

As for the comment about nonmetallic (Romex)...so does that mean 90% of the homes in the US are using garbage?

 

[racin72charger]

I’m doing all surface mount emt for all the outlets. I did romex in the ceiling for the lighting. I prefer the “industrial” look of the emt personally.

 

[Bert_]

Guessing 120v outlets isn't the problem but rather 240V stuff for equipment. Hard to plan for equipment you don't have or haven't even thought about yet. It can be done to some extent in a home shop because most equipment gets used one at a time so circuits can be shared.

Conduit is great because even 30+ years later changes can be made without opening up walls. I know I can't plan 30 years into the future. Again it is less of an issue in a home shop because it's not that big of space and so it isn't that hard to just run a new piece of romex.

Emt in the wall makes for a very nice install and isn't as hard as you might think. It does take more time than romex though, but not any more time than running on the surface. If cost were not a major concern I would do it more often, I actually kind of like doing it. I have repulled wiring and added circuits in buildings so old they were wired in rigid before emt was even invented. Now that would have been hard work, wiring a whole school or something, and threading all that conduit by hand!

 

[7635tools]

I'm curious how many people actually make a lot of changes after the initial install...if you plan it out right I would be surprised if you have to.



As for the comment about nonmetallic (Romex)...so does that mean 90% of the homes in the US are using garbage?

In my opinion yes it’s garbage. Would you run extension cord in your walls? Romex is not much different.


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[Bert_]

In my opinion yes it’s garbage. Would you run extension cord in your walls? Romex is not much different.


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Would you use romex for an extension cord? It is different.

How about MC? after all its practically the same thing, all it has is that flimsy aluminum jacket...

 

[7635tools]

I'm curious how many people actually make a lot of changes after the initial install...if you plan it out right I would be surprised if you have to.



As for the comment about nonmetallic (Romex)...so does that mean 90% of the homes in the US are using garbage?

Wrong. This is not a house it’s a garage/shop. I’ve added several machines over the last few years and have had to rearrange equipment to accommodate. A shop is always evolving.


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[7635tools]

Would you use romex for an extension cord? It is different.

How about MC? after all its practically the same thing, all it has is that flimsy aluminum jacket...

Extension cord and romex are very similar in construction. It’s insulated wire with a outer plastic jacket. Other then one being stranded and the other solid I’d say they’re very similar. MC cable is a step up but still inferior to conduit.


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[86turbodsl]

I put outlets every pole on my pole barn, in the wall in romex. That'll never change. On 240v machinery that moves around, i just run conduit as needed. Hybrid and best of both worlds, cuts down on cost and is still flexible.

 

[Git]

I had a good laugh at 'romex is garbage'

Anyways, you mentioned you want to place the outlets about 4' 2" up. Think about this - lay your first row of drywall (or OSB) horizontal, and then leave a gap of a couple of inches inbetween the next row. This 'gap' will be where you run your garbage (I mean romex wiring) in the wall. Then use some sort of trim board to cover the gap - and you can even mount a box horizontally to the trim board if you wanted

Here is an example of what I am talking about. I have what I call 'cleat wall' installed on two walls in my garage. They are strips of 3/4" plywood, about 3 1/2" wide with the top edge cut to a 45 degree angle to hang things on. The cleats are wide enough to handle a single gang outlet but if I wanted to make any changes, all I have to do is unscrew that cleat from the all and I can access the wiring behind it

Just another thought on how to do it

 

[PNWguy]

I had a good laugh at 'romex is garbage'

Anyways, you mentioned you want to place the outlets about 4' 2" up. Think about this - lay your first row of drywall (or OSB) horizontal, and then leave a gap of a couple of inches inbetween the next row. This 'gap' will be where you run your garbage (I mean romex wiring) in the wall. Then use some sort of trim board to cover the gap - and you can even mount a box horizontally to the trim board if you wanted

Here is an example of what I am talking about. I have what I call 'cleat wall' installed on two walls in my garage. They are strips of 3/4" plywood, about 3 1/2" wide with the top edge cut to a 45 degree angle to hang things on. The cleats are wide enough to handle a single gang outlet but if I wanted to make any changes, all I have to do is unscrew that cleat from the all and I can access the wiring behind it

Just another thought on how to do it

Romex is total ****. Every house I've ever lived in has burned down.

I love the idea for hiding the wires behind a cleat. Very clever and solves some of the issues.

 

[PNWguy]

Guessing 120v outlets isn't the problem but rather 240V stuff for equipment. Hard to plan for equipment you don't have or haven't even thought about yet. It can be done to some extent in a home shop because most equipment gets used one at a time so circuits can be shared.

This is exactly what I'm thinking of.
My father is 80 and starting to slow down. Since my shop is (will be) heated, and his isn't, I expect some of his equipment to migrate to my shop. But I'm not sure what will be first - the mill and lathe that we own together? The welding gear? Sheet metal tools?

Unless I run 240 everywhere, I'll probably be making changes in the future. All the calls of "just do a little planning" are kind of annoying.