Wiring Metal Shop

[cwsample]

I'm hoping all you more experienced builders can give me some ideas on how best to tackle this; this is my first shop build, so I'm trying to make sure I do it right the first time.

I have a 30' x 40' metal building with a free-span metal frame that has been spray-insulated. I'm trying to not do a lot of framing/plywood throughout, minus the bathroom in the corner. I've installed the panel, but I'm trying to figure out the best way to wire the rest of the shop. Since I don't have wood studs to drill through for my wiring, my first thought was to use either EMT or PVC conduit along the metal perlins, but then I don't have a way to support the boxes for outlets, switches, etc. Minus doing at least a stud or metal bracing for each drop, what would you all suggest? Pictures below for reference of my set up. Bathroom (including drops for 220v water heater and clothes dryer) is in the opposite corner of the panel, so I have a bit to run.

Thanks in advance for your ideas!

 

[readhead]

I'm not a fan of spray foam but that has to be the cleanest installation I have ever seen. Unfortunately not enough planning was done for the building to address your problem. In similar situations I have seen unistrut installed from the floor up to the first girt to install the boxes on like how the panel is installed. When I sell a building I include a girt at 4' above the floor which is handy for a lot of things including electrical work. Was a UFER ground installed? Of course the frame needs to be bonded also. Keep us posted on your progress.

 

[aka Larry]

Wow, that is _the_most_even spray foam installation ever!

 

[Gummi Bear]

Nice shop!

Definitely use EMT.

I wired my shop in EMT (I’m an electrician) and ran it on the face of the purlins. I basically ran a 1” all the way around for power, and dropped down to the 4’ level for receptacle locations. I can add circuits as needed.

For the ceiling, i ran a raceway system, and use MC for fixture whips.

Mount everything as high and tight as you can.



I went to the woods because I wished to live deliberately...

Henry David Thoreau

 

[trackwelder]

Just curious what you plan on doing in the new space? Myself I would want at least 8’ high plywood to protect the foam insulation, and provide a nailing surface for conduit, cabinets etc.

 

[sberry]

I wired my shop in EMT (I’m an electrician) and ran it on the face of the purlins. I basically ran a 1” all the way around for power,

I understand from an electricians point of view but,,,, I use all 3/4 for the large pipe and run another short pipe or 2 for more local circuits, welder and comp, might even provide their own pipe for those circuits.
A guy that does commercial will have the inch stuff but for diy types its just adding another size and box style.
I just went and looked at one today, guy was going to put a comp on other side of the shop away from the panel instead of in the mechanical room 3 ft from it. A whip will reach the box. It will put it in a room out of the work area.
It would get a little 3/4 here and mostly 1/2, I might splurge a bit on 4x4 boxes and get deeper ones as new gfci need the room. This size building could get by on a single welding outlet not too far from the panel, a section of 3/4 or 2 to get headed out of the panel and to a box and most the rest in 1/2 where a guy can buy a box of 100 connectors, common boxes he can use up and have a couple pieces left over to add stuff as needed.

 

[Norcal]

Nice shop!

Definitely use EMT.

I wired my shop in EMT (I’m an electrician) and ran it on the face of the purlins. I basically ran a 1” all the way around for power, and dropped down to the 4’ level for receptacle locations. I can add circuits as needed.

For the ceiling, i ran a raceway system, and use MC for fixture whips.

Mount everything as high and tight as you can.



I went to the woods because I wished to live deliberately...

Henry David Thoreau

If the fixtures are suspended by chains, stranded conductors are required, most MC cable has solid conductors.

 

[Gummi Bear]

If the fixtures are suspended by chains, stranded conductors are required, most MC cable has solid conductors.

Where did you get that idea from?

That may be a municipal requirement, but certainly is not in the NEC

I run solid MC to suspended fixtures all the time. Just zip tie it to the chain or aircraft cable supporting the fixture.

Stranded MC is available. I order it when specifications will allow me to use it (usually 1-3 days, it is in a regional warehouse). It’s really fantastic.



I went to the woods because I wished to live deliberately...

Henry David Thoreau

 

[Norcal]

Where did you get that idea from?

That may be a municipal requirement, but certainly is not in the NEC

I run solid MC to suspended fixtures all the time. Just zip tie it to the chain or aircraft cable supporting the fixture.

Stranded MC is available. I order it when specifications will allow me to use it (usually 1-3 days, it is in a regional warehouse). It’s really fantastic.



I went to the woods because I wished to live deliberately...

Henry David Thoreau

It is in the NEC just unable to quote the article number right now.


410.56(E)

 

[Gummi Bear]

I see how you came to that conclusion. It’d make an interesting conversation with an inspector.

I think that is referring to something like chandelier wiring woven through a chain.

I don’t see anything about industrial strips that are chain hung. 410.24(A) could be an argument for MC to feed a fluorescent or LED strip.

I’ll ask around.


There’s a lot in 410 that is in desperate need of revision and clarification.



I went to the woods because I wished to live deliberately...

Henry David Thoreau

 

[Norcal]

I see how you came to that conclusion. It’d make an interesting conversation with an inspector.

I think that is referring to something like chandelier wiring woven through a chain.

I don’t see anything about industrial strips that are chain hung. 410.24(A) could be an argument for MC to feed a fluorescent or LED strip.

I’ll ask around.


There’s a lot in 410 that is in desperate need of revision and clarification.



I went to the woods because I wished to live deliberately...

Henry David Thoreau

There are no qualifying notes so IMO, it covers any fixture suspended by chain.

 

[Astross89]

I have no idea what this thread is about. But that spray foam..........

 

[cwsample]

Hah, I wasn't expecting to get so many comments on the foam. I'm very happy with how it turned out. Thank you for all the comments so far. As for the electrical project...

I decided on 3/4" EMT to run around the perlins, then just drop down when I needed an outlet. A 10' stick of 3/4" is about $5 each at Home Depot; the 1" stick was over $9 each. Buying a bundle of 10, that's a big increase. I will use the same struts that the panel has so it matches. I did 1 run today with 1 strut installation, and it seemed to go together fairly well. Time will tell as I get further into the install. I'll put some more pictures up once I get some more done.

The biggest hurdle so far has been the bathroom on the opposite corner from where the panel is. I think I am going to install a sub-main panel to run the water heater, clothes dryer, as well as lights and outlets in that corner. I have about an 80' run that I need to power about 100 amps. I'm thinking #4 wire should be enough, but the guy at Home Depot said I needed #3. There's a pretty significant cost between the two. Thoughts?

 

[Norcal]

4 AWG is not suitable for 100 amperes in your application, the Home Depot guy is right for a change.

 

[bjcouche]

In my shop I put a 30A subpanel just outside the bathroom. It was a cleaner install, but came out cheaper than running multiple cricuits all the way back to the main panel. In the bathroom subpanel I have circuits:
20A 120V for outlets
15A 120V for lights
20A 120V for electric baseboard heater
20A 120V for 120V point of use water heater (under sink)
Based on the loading and which loads are on which line, a 30A rated subpanel was fine.

Other things, what do you plan on covering the spray foam with? You do know it must be covered because it is not supposed to be exposed to UV right? One option I've heard of is a special type of paint..... I spray foamed my whole shop and then covered teh entire interrior with similar metal as the exterrior.

In the bathroom, I know you are in Texas, but unless you plan to keep the whole shop area heated above freezing... In my shop I don't heat the entire shop continuously. I keep the bathroom (also insulated) heated and all the water plumbing is kept inside the bathroom. So in your case it would be a combination bathroom / laundry room.

 

[Lelandwelds]

If you avoid peak hours,ma good electrical supply house can beat HD pricing. Why wasnt the place wired before the foam was sprayed?

I would cover that foam with sheetrock or sheetmetal or something that wont burn. My foam guy wasnt that good. They shaved off enough excess to fill a cargo van box and still had places so thin they had to spray a second time. He got so much on the floor that all the trades tracked it everywhere inside and out.

 

[75gmck25]

You could run 2-2-2-4 AL wiring to the subpanel and just use a 90 amp breaker in the main. The 2-2-2-4 would require fairly large conduit, but its such a common wire size that its usually quite a bit cheaper. You can still use a 100 amp sub-panel (lots of space for breakers), since current will be limited by the main panel breaker.

Bruce