steel building wiring questions

[bdog]

I am going to wire my 50x50 steel building using 3/4" EMT. My question is the building has 6 - I beam main frame supports, one on each corner and one on each side in the middle. The base of the building has a base angle running along the floor, one 8" purlin 7' above the ground, and then one at the top.

I was planning on attaching the conduit and outlet boxes to the middle purlin on the building but I did not realize it was going to be 7' off the ground.

Any ideas? 7' high outlets do not seem like a good idea neither does putting them all the way down on the floor. My I beams are 25' apart so the emt can't span that without support.

 

[mrb]

you will have to have your horizontal run @ 7ft then drop down to boxes on the columns. If you require receptacles inbetween the columns, you will need to span from the purlin to the floor with a piece of unistrut, or fab a column or pedestal for the box to mount to, then drop down to it with your emt.

 

[mrb]

another thing you could do, is everywhere you need a receptacle, you can put a 4S box at the 7ft level, then have a cord pendant like the one pictured below hanging from it.

 

[Charles (in GA)]

another thing you could do, is everywhere you need a receptacle, you can put a 4S box at the 7ft level, then have a cord pendant like the one pictured below hanging from it.

At very nearly $50 apiece, I doubt he will want to buy very many of these.

Charles

 

[Charles (in GA)]

This thread discusses the same issues. I won't bother reposting my pics here.

http://www.garagejournal.com/forum/showthread.php?t=45591

Charles

 

[mrb]

At very nearly $50 apiece, I doubt he will want to buy very many of these.

Charles

was just a suggestion, and they can be had for much less than $50 ea.

 

[Aceman]

I personally can't stand steel buildings made that way. I don't know if folks are cheap or what when they order these buildings. Everyone including the builder know most folks buying these buildings for shop/garage use are going to have electrical, air, etc that'll need to hang somewhere around the 4' mark so why not throw up one more piece of z-channel at that height? Then they give you the deer in the headlights look when you ask them how I'm supposed to mount receps when there is nothing there....

Coincidentally, I just wired a storage building exactly like you described, they threw up a chinsy steel stud wall to span between the ground and that 7' z-channel. Then they sheathed the interior with white corrugated plastic. It was a bear screwing down boxes without crushing the corrugations. I had to straddle the ribs and use spacers on each side....hopefully never again.

 

[Charles (in GA)]

was just a suggestion, and they can be had for much less than $50 ea.

http://www.woodhead.com/data/current6657/multiple outlet boxes 902.pdf

http://cgi.ebay.com/Daniel-Woodhead...lectrical_Equipment_Tools?hash=item4149bbed16

http://www.toolfetch.com/Brand/Daniel_Woodhead/Lighting/840-3000.htm

http://www.kirbyrisk.com/index.jsp?path=product&part=1826589&ds=dept&N=13104&Ne=10000

http://www.kirbyrisk.com/index.jsp?path=product&part=508216&ds=dept&N=13104&Ne=10000

http://reviews.shoplet.com/Daniel-w...utlet-Box-Receptacles-3000/SEPTLS8403000/spdv

 

[mrb]

whats that? a list of woodhead boxes?

 

[Charles (in GA)]

whats that? a list of woodhead boxes?

No, basically just pointing out that finding one substantially below $50 is not easy to do. Some places are horribly overpriced, but you gotta go to Ebay to find anything "reasonable". We use these boxes on our extension cords at work and I thought it would be neat to have the same at home until I found out what they cost. Someone else may make them, but I would not know who, as I've never seen anything else like them.

Conform to all the rules on pennants (strain reliefs, supporting cables, etc) and the piece of uni-strut and a box and EMT begins looking real nice.

Charles

 

[Charles (in GA)]

I personally can't stand steel buildings made that way. I don't know if folks are cheap or what when they order these buildings. Everyone including the builder know most folks buying these buildings for shop/garage use are going to have electrical, air, etc that'll need to hang somewhere around the 4' mark so why not throw up one more piece of z-channel at that height?

Like everything else, it all costs money. I know one building manufacturer in Georgia (Bax Buildings) that uses C channel instead of Z material for wall girts and roof purlins, and even puts one at floor level rather than an angle like everyone else, but its like a Yugo compared to a Lincoln. It all adds up when you do this. Add one more z purlin to a 50 x 50 and thats about 200 ft more material, attachment clips, bolts, labor, etc. It all adds up. Not saying it wouldn't be nice, just that people don't like to pay for what they don't (structurally) need.

Charles

 

[rburke65]

Sort of like that welder question....8-2 wire or can I use 12-2!!! "just that people don't like to pay for what they don't (structurally) need." Same story.

 

[bdog]

I just called the steel supplier and the 25' 6 inch c purlins are $25 each. One wall of my building is all doors so 6 purlins will do the trick. $150 and a couple hours work and I will have another purlin run @ 4'.

 

[Aceman]

I just called the steel supplier and the 25' 6 inch c purlins are $25 each. One wall of my building is all doors so 6 purlins will do the trick. $150 and a couple hours work and I will have another purlin run @ 4'.

Well there you go, good deal.

4 square deep bracket boxes work pretty good when you mount to the purlin. Run your pipe right on top of the purlin and box offset in and out of the bracket boxes.

The other way I've seen but haven't done because it isn't very convenient for pulling wire through boxes is they'll mount 4 sq boxes right to the face of the purlin. They'll leave just enough of the box sticking up above the purlin to 90 in and out of the back of the box. It can get pretty tight though trying to make a 90 fit behind the box when you're running 3/4 emt. You usually end up bending the tightest 90 you can and then chopping part of the stub off to make it work.

 

[sberry]

Purlins are in the roof, sheeting girts in the walls. Base channel is often used vs angle when there is inside wall sheeting going on.

 

[Charles (in GA)]

Here is what I did at the wall girt boxes mid way between the columns.

I used a thin 4 inch box and ran two separate circuits, two hots, two neutrals, two grounds and spliced everything in the box on top of the girt and ran pigtails from the splices into the box on the face of the girt. The two boxes are joined by a close ****** or a 1" ******. Later I went back and added the extension boxes because I did not like how much stuff was in the 4 inch box by itself (though I think it did calculate out as being Ok on the wires and cu inch).

The box is unused and I have the receptacles plugged with plastic childproof protectors, one is solid others are translucent, but the purpose is to keep dirt daubers or mud daubers from building in the ground pin holes.

I have to plug all my coiled up extension cords ends together and the same with air hoses. Also have the fire extinguisher hoses capped (caps come off easy, would blow off if used).

Charles

 

[Aceman]

Purlins are in the roof, sheeting girts in the walls.

I always get it backwards....

 

[bdog]

Purlins are in the roof, sheeting girts in the walls. Base channel is often used vs angle when there is inside wall sheeting going on.

Are you saying they call them different things based on where they are used? The purlins / girts on the walls and the ones used on the roof are identical on my building. They are all 8" C - purlins.

I was going to use 6" for the outlets because it is cheaper.

 

[bdog]

Charles - Are those outlets installed on a 7' girt? If so do you find it inconvienent? I am 5'10 and can reach it but it is a bit of stretch. Would be really difficult if something was up against the wall.

 

[Charles (in GA)]

Charles - Are those outlets installed on a 7' girt? If so do you find it inconvienent? I am 5'10 and can reach it but it is a bit of stretch. Would be really difficult if something was up against the wall.

I use the high up ones for stuff that is permanently plugged in, the lights and vac of the blast cabinet, the refrigerator, things like that. I have outlets on each of the columns, and in the corners, at a more normal height, about 4 ft if I recall. I only did the ones up on the girts in three places, the rest of the building the outlets are 20 ft apart as they are only on the columns. I also have outlets on the legs of the workbenches, which are freestanding, and from a junction box on the back of the workbench is a cord that plugs in an outlet. These are handy boxes which come with brackets and are screwed to the legs of the workbenches. I originally had outlet strips but they proved to be junk and I replaced them with the handy boxes on each front bench leg.

Charles

 

[sberry]

Are you saying they call them different things based on where they are used? The purlins / girts on the walls and the ones used on the roof are identical on my building.

Yes, a 2 x 6 may be used in a wall where its a stud and be a purlin in a roof.

 

[rburke65]

And if it still has the bark on it, its called a tree!!!I'm sorry....I couldn't help myself.

 

[Ign]

Hmm........my building was custom fabbed by a local guy. He suggested sheeting girts at 4' level and 8' level. 8' because people usually put up 8' interior sheeting to protect the first 8' of insulation (which I did) and 4' to provide another place to anchor the sheeting midway. The distance between the 4' and 8' also makes a great place to put windows.

I put up a 26ga propanel-esque sheeting inside and screwed all my boxes and EMT straps directly to the sheeting using tek screws (not standard self-tappers but tapered self-tappers which grab thin metal far better)

So..........I guess what I'm saying is that interior sheeting would make your life a lot easier, and personally there's no way I could have a fab shop w/out protecting the lower insulation anyhow.

edit: I'd also suggest using 1/2" conduit where you can; it's a lot easier to work with (can damn near bend it by hand) and will cut overall cost too. Personally I ran all my 220 in 3/4 and all my 110 in 1/2. Of course my 220 is 6ga, 50A