surface wiring

[Tom Godley]

One section of my shop has no power -- it is SIP building so surface wiring is the only way to go.

My plan is to run a wire out to a new surface mount sub-panel and go out from that point.

I have worked with both metal conduit and plastic conduit over the years -- I am leaning toward the metal for this project.

I am also trying to decide on the outlet layout. I have seen some who have wired with outlets every 10 feet or so -- some even using twin boxes giving 4 spaces at each location.

I did see one shop that had duplex boxes with a 110 duplex outlet and a single 220 outlets together -- this struck me at the time as a good idea - not so sure now.

I understand that more is better -- but am trying to get an idea on spacing. Often 10 feet is used only because that is the length of the pipe used?

I was going to place the outlets at about 52 inches high - but was also wondering about those used for larger tools and what height would be best.

For those who have done this - any good ideas on what you have done that you like or dislike?

[Rod Sheridan]

Hi, I have 4 inch square boxes at 6 foot intervals in my shop, using 1/2" EMT.

The boxes are fed from one 2 pole 15 ampere breaker that provides a single 15 ampere circuit at 240 volts and 2 15 ampere circuits at 120 volts.

This supplies all my 240 volt machinery (most 3HP), and all me 120 volt machines and portable tools.

There is also a single 15 ampere 240 volt circuit for my cyclone.

In your case, now that 20 ampere T slot receptacles are available, use a 20 ampere feeder and install a 20A 240V receptacle, and a 20A T slot 120V receptacle in each 4 inch box.

It's a great way to wire a shop............Rod.

[Jim Becker]

My preference is for metal conduit for this, despite plastic being easier to deal with. Since you can buy components including bends just as you can with plastic, you can put it in place without having to learn how to bend conduit if you want. Place your outlets for convenience but I have found that it doesn't necessarily pay to have a million of them--more is not necessarily "better", in other words. I keep a short extension for those few hand-held electrics with short cords and since most of my hand-held electrics are Festool, they plug into the vac which has a very long cord. (requires a real 20 amp outlet unless you use an adapter)

I'm personally not in favor of putting 240v machine circuits in the same conduit/boxes as the 120v circuits, largely for flexibility over time. I like bringing these out to large J-boxes and running individual drops from there so that as time passes and new/different tools come into play, it's easy to move a circuit and most of these are dedicated to a particular tool. These drops in my shop are all in vertical conduit down the wall to an individual box. This method also makes it easy to have more than one position for a 240v circuit for sharing of some tools that one could never operate simultaneously--branching in a big J-Box is easy to do and to change. Now, if you want to get fancy, you could use a raceway on the wall to make for easy changes, too, but that can add to the cost substantially over just plain conduit.

As to height, 52" can be convenient in general, but might not be what you want for specific tools. There may be some cases where a ceiling mounted strain relief, twist lock setup might be the right solution for something out in the middle of the shop. In other instances, I've found that a normal 18" level outlet is convenient for some things, too, so I have both low and high outlets in my shop.

Note that my comments are all from a practical standpoint...and in no way address electrical code, etc.

[Von Bickley]

My shop is wired with 1/2" EMT. I know some people will say that you should use 3/4" but I personally like working with 1/2" better. I used mostly 4" boxes and installed 2 duplex receptacles in each box. I installed my 220 volt outlets in separate single gang boxes (handy box).

A lot of people will say to mount your boxes at least 48" high so you can lean plywood against the wall and still be able to get to the receptacles. I mounted my boxes about 44" high because I personally like that height. Just a personal thing. I have plenty of receptacles so it's not a big deal with me.

I have a 400 amp service on my shop with a 200 amp panel designated for mostly "shop stuff". You will also want to have your lighting on separate circuits. :)

[Tom Godley]

I have used the plastic for outside projects around the the house quite often - enough that I invested in a heating blanket to save the cost of buying the 90's - it also gave me the ability to make strange bends and offsets.

My feeling with the metal was that it would be easier to attach to the flat surfaces in the shop - not sure of the cost difference? I do have a simple bender that you attach a pipe (handle) to - but I have not used it in years and I remember a "learning curve" with the thing.

I just never sat down and tried to do a lay out!

I want to keep the wall space open for future cabinets -- both above and below - trying to keep it simple.

When you start to think of running lines for compressors and duct collectors -- it can get busy

[Chris Damm]

I used plastic conduit and mounted a duplex box about every 5' (conduit is 10' so cut in half). Every wall is on a separate 20 amp circuit. This has worked very well for me. I also mounted the bottom of the outlets 50" off the floor even though my wall space is covered with machines. I like surface mounting because it is so easy to change and you will want to change it!

[Rick Moyer]

Good thread that I will be watching as I am in the same situation. I will likely be using plastic as my BIL has a bender. I like the "every 5 ft" idea to save cutting. Q: Do most prefer to run electric down the middle of the ceiling and then branch off from there, or down one or two sides? Not sure I'll run air as my compressor is portable, but the DC duct work will come into play with the electrical. All ideas are appreciated!

[Myk Rian]

The boxes are fed from one 2 pole 15 ampere breaker that provides a single 15 ampere circuit at 240 volts and 2 15 ampere circuits at 120 volts.

I've seen this done at work. The problem was having a 240 volt potential between 2, 120 volt receptacles. The electricians had to rewire the entire shop to get rid of that problem.