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-   -   Is it legal to run wires on the ground, in conduit? (http://www.diychatroom.com/f18/legal-run-wires-ground-conduit-95749/)

Red Squirrel 02-17-2011 07:00 PM

Is it legal to run wires on the ground, in conduit?
 
I've been planing out my server room electrical a bit in my head and because the UPSes will be at the bottom of the rack, and the electrical panel will be on the wall behind said rack, it makes more sense to run the power down the wall then on the ground to the rack.

If I was to do this, using conduit, and it would eventually be covered (accessible) with some kind of raised flooring, would this be legal? The raised flooring would probably be something custom, maybe 2 inches off the ground. I'd probably use PVC conduit and run maybe 6 15 amp circuits through it. I did not research what the fill limit per conduit size is, so if that's too much then I'd just run multiple conduits as required. Just wondering if there is anything wrong with conduit on the ground like that. I'm guessing no.

If I was to run just the bare wires, then that would not be ok right? What about BX? I'm actually thinking of going all BX for this room just to shield the wiring as it's possible I have cat6 runs pass near electrical. Is BX ok in a conduit?

jbfan 02-18-2011 06:10 AM

Nothing wrong with running conduit on top of the floor.
I would run induvidual condutors, and not nmb.
Thhn/thwn would be the wires of choose.

Red Squirrel 02-18-2011 11:51 PM

By individual conductors, you mean individual 14/2 wires, or actual conductors? I can see this for a sub panel or what not, but can I actually do this for individual circuits? So I could just have like 6 black, 6 white and 6 grounds in there?

Also what is the best/legal way to go from conduit to outlet?

jbfan 02-19-2011 07:44 AM

6 blacks, 6 whites, 1 green
6 blacks, 3 whites, 1 green, and 2 pole breakers for a MWBC.
Don't use 14/2, use single wires.

darren 02-19-2011 11:46 AM

If you go with the single conductors you will have to use #12 to allow for derating in the pipe and a #14 ground if you use PVC. If you go EMT(which i would do) you do not need a ground.

So that would give you 10 conductors if you count the ground. 3/4" pipe is good for 11 #12 conductors(if you use RW90). If it were me I would up the pipe size to 1"(good for 19 #12 RW90) for any future additions and ease of pulling if it is a longer run.

Red Squirrel 02-20-2011 09:44 PM

For my application EMT would actually be nice, as it would also help shield the electrical wires to prevent interference with the possible cat6 that may pass near and give me that "industrial" look too. Only thing, I do need quite a few special tools for that right? Cutting, bending, threading etc?

Also whether I go PVC or EMT, when I get to the end of the conduit, how do I transition to individual plugs? Would I use a conduit jbox attachment, then wire nut to regular 12/2 then run to individual boxes?

Also if I go with bigger conduit, is it ok to use BX inside of it? That may be cheaper then EMT, and give me shielding capabilities as well. Or could I actually run the BX straight on the ground? (guessing no)

The run would actually be very short if I put the panel where I plan. Panel would be 2 feet or so from the rack, at eye level, so circuits would run down that wall, then on the ground, and to the rack then convert to individual outlets. I'm thinking 3 15a MWBC circuits using 12awg wire. I actually use 12awg for almost everything. If figure it never hurts to go a big bigger.

LyonsElecSupply 02-20-2011 09:51 PM

You have to derate your conductors once you go above 3 inside one conduit.

The NEC defines your derating based on CURRENT carrying conductors, which INCLUDE your neutrals AND hots.......

Also, run your cat 6 PERPENDICULAR to line voltage to limit interference.

A Squared 02-21-2011 12:20 AM

Quote:

Originally Posted by Red Squirrel (Post 594805)
For my application EMT would actually be nice, as it would also help shield the electrical wires to prevent interference with the possible cat6 that may pass near and give me that "industrial" look too. Only thing, I do need quite a few special tools for that right? Cutting, bending, threading etc?

You can cut EMT easily with a hacksaw (make sure you ream the cut so there are no burrs ) and you don't thread EMT, so the only special tool you might need would be a bender. Even that you can might get around by using ell connectors. A bender for EMT costs about $45 at Home Depot

nap 02-21-2011 12:20 AM

Quote:

Originally Posted by LyonsElecSupply (Post 594811)
You have to derate your conductors once you go above 3 inside one conduit.

The NEC defines your derating based on CURRENT carrying conductors, which INCLUDE your neutrals AND hots.......

Also, run your cat 6 PERPENDICULAR to line voltage to limit interference.

he's in Canada. They might have the same rules but it would be based on the CEC (or whatever code they use in red's neighborhood), not the NEC.:wink:


Red, even if you use emt, I still recommend an egc (ground) conductor.


and for emt, no threading. a whacksaw, something to ream the ends of the pipe, and a bender.

To go from conduit to an outlet, you use a connector that attaches to the box and the conduit fits in it.
http://www.o-digital.com/uploads/217...w_Type_441.jpg

Red Squirrel 02-21-2011 08:22 AM

Hmm that's good to know, I was getting confused with rigid steel conduit. So the EMT pipe just fits in there, and I use the screw to tighten it and other end in box/panel like clamps.

For what it's worth I might go that route then, and buy the bender. I was picturing EMT as being the bigger pipe, but I forgot there are single circuit EMT as well which will probably be easier to work with. I could put my 4 wires (MWBC) in there and go from panel straight to plug box and have 3 seperate runs. Now that I think about it since the plugs will be on the ground I should probably upstream GFCI protect those by making them pass through GFCI outlets. (cheaper then breakers) before going down.

Anyone aware of any codes here in Canada about having plugs on the ground?

slickwilliam 02-21-2011 08:43 AM

The OP did mention a server room. Typically, server rooms are built for (among other things) ease of adds, moves, or changes. Not knowing how large or dynamic your environment will be, I would nonetheless recommend using sheathed flexible metallic conduit (a.k.a., Sealtight, etc.), especially if you anticipate putting it under a raised floor. The ability to scoot outlets around as things change is great!

Our whips are almost all Sealtight with three L6-20s at the load end. That puts six current-carrying conductors plus the ground in the tube, an easy pull even when using 10ga THHN. (And I also recommend 10ga because you'll have the option of either 20a or 30a (L6-20 or L6-30) circuits. Of course if you're running 110v circuits (not recommended for "real" servers), this'll change somewhat.

Red Squirrel 02-21-2011 10:54 AM

This is a home server room so once I have the power drops, not much will change. I may add a few 30a circuits in the future if I get a UPS that requires a 30a plug, but that's about it. Actually going quite overkill for this, better too much power then not enough. Most if all will be 120v circuits as while lot of equipment can run at 240v, all can run at 120v, so easier to just have all 120v. Of course this could also change at some point. Any advantage to running stuff at 240v?

A Squared 02-21-2011 12:51 PM

Quote:

Originally Posted by Red Squirrel (Post 594955)
Hmm that's good to know, I was getting confused with rigid steel conduit.

Ignoring flex conduit and PVC conduit, there is EMT (Eletrical Metallic tubing) , IMC (intermediate Metallic Conduit) and RMC (Rigid Metallic Conduit)


EMT is the lightest, you could dent EMT pretty easily by smacking it with a hammer. It's assembled with slip-on connectors. Rigid is the heaviest and uses threaded connections. IMC is in between the two in heaviness, and uses either slip on or threaded connectors. EMT and IMC can be bent with hand benders, although you need a 3/4" EMT bender to bend 1/2 ' IMC. Rigid Conduit requires a bending machine.

SD515 02-21-2011 02:15 PM

1/2" through 1" Rigid can be bent with a one shot hand bender. May not be any fun, but it can be done.

slickwilliam 02-21-2011 07:02 PM

Best reason to run things at 208 (or 220, whatever) is less current draw. That means less voltage drop on longer runs and thinner power cords on the servers -- 14 or 16ga rather than 12 or 14ga. When you've got a biggish bundle of cords in the racks, thinner cables makes a big difference. But for your application, it wouldn't matter much.

Sorry, I run a data center and when someone mentions server room, I get all excited... :thumbup:


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