UPS in machine room . . ?

[mpmusicny]

Hi guys –

I have an electrical wiring question.

I’m in the process of renovating my composer’s room. In the past, I have run my entire rig off one UPS which I have up until now kept next to my computer and drives underneath my work desk. Draws only about 6 amps total. All the noisy stuff is now going into a small “machine room” next door, and I am wiring 2 dedicated receptacle circuits for the studio, one of which will include the receptacles on the other side of the wall in the machine room. Question – I also intend to have a floor receptacle under the desk so that all the wires coming to the desk, power, monitors, Firewire, USB etc can be run via conduit under the floor from the machine room = no mess on the floor. I want to do everything to code. Is it legit to run NM from the floor receptacle to another receptacle in the machine room which the UPS can then connect to – basically a permanent extension inside conduit? My instinct says this may not be good, but I know not why. Another option would be to have a second UPS under the desk and wire the floor receptacle as a standard outlet.as part of one of the 2 main circuits. Not a huge problem as the UPS itself appears to these ears to be all but silent, but it is more money, lost legroom under the desk, and won’t look so good . .

Is there a standard practice for this?

Thanks!

Malcolm

[aackthpt]

I don't know code much, so when I say I suspect there's a code-approved way to put an extension cord coming from the wall it's likely to be wrong. From what I read the issue is that you can't run stranded wire carrying 110 through walls (low voltage is OK). So I think if you put a single-gang box and in it wire-nut the romex to a stranded cable and wall plate (with appropriate strain reliefs) it might be OK. One thing I do know is that having a male-to-male extension cord is going to be code-illegal. That's because it's always female connections for power sources and male connections for power consuming devices, probably that is to avoid having bare/accessible terminals with 110 on them, which you would have with a male-to-male cable. Another reason you can't have a male-to-male cable is because someone might connect a generator to a wall plug to backfeed the system, which will cause the generator to explode once line power is restored (if the main has not been disconnected).

However the solution that I know for sure would be OK is to use this kit which is what the home theater guys use to mount a UPS in their equipment room with the projector on it. The outlet one of these goes near the projector and is wired back to this male plug one with romex. Back in the equipment room you just run a standard heavy duty extension cord from the plug one to the UPS and the UPS plugs to a standard outlet there (of course).

That one is obviously specialized for that type of use since it has the pass-through openings for the LV stuff too. I'm not sure if there is a way to do this for more outlets (I imagine there would be but if it isn't home depot type stuff I wouldn't be surprised if it were comparatively costly) but I don't see anything wrong with using a single outlet then a strip for all the gear as long as you stay within current limits for everything.

[mpmusicny]

Thanks, aackthpt

i do know that the floor receptacle will have to one that is rated as such - it has to be protected against dust and liquids entering it. this is not cheap, but looks like a perfect box. It can come with blank inserts which i can drill for the kinds of sockets i will need . .

http://www.tnb.ca/en/fichier/whatsne...u/SC668S_E.pdf

[ritelec]

Originally Posted by mpmusicny

Is it legit to run NM from the floor receptacle to another receptacle in the machine room which the UPS can then connect to – basically a permanent extension inside conduit?

Yes. It's not an extension chord, it's NM or NMB. And even if it was an extension chord, if it was in conduit would be ok. They don't want exposed extension chords going thru walls or floor to floor. Here's possible problems. If you run more than two (4 conductors with 2 grds) then you have derating factors to deal with. Also the size if the conduit for those conductors. Also mixing communication and power power together in the same conduit. Insulation would have to be rated for the voltage, not to mention interference or crosstalk. Fire stops (the red stuff) between rooms and or floors.

Edit: those floor boxes are nice...$$$. Concrete floor? commercial building? Your getting permits right??? ha ha ha ha.........I won't tell.ha ha ha ha...

[mpmusicny]

ritelec,

thanks very much for the input.

Point well taken on mixing up types. My plan was to run all computer cables and signal cables parallel but at a distance of some feet and then do a 90 degree turn when they reach the distance of the floor receptacle, so that voltage lines and everything else approach each other at right angles, but never actually cross.

As regards derating, i must admit this was something i had not considered. the UPS has multiple outputs with different functions ( 1 master, 5 full battery back up, a few just surge protected) and i had assumed i could run 12 gauge NM through multiple conduits to utilize as many outputs as possible. can you explain to me why i could run into derating problems in a set up like this?

Thanks for confirming that it's doable though - I guess the outlets (well actually inlets) at the UPS should be marked so that strangers understand that it's not a regular outlet, and that plugging something into it is not going to get you any power. . . actually stricyly speaking, should they be recessed male sockets?

on a related note, I am wondering wether it's necessary to make the power feed for the UPS a separate circuit with isolated ground - any thoughts on that?

thanks!

Malcolm

[ritelec]

I meant not in the same conduit mixing the wires.

2 conduits are good.

Is the ceiling underneath a plenum ceiling?

You could also do MC and plenum rated low voltage (no conduits).


Conductors crossing........ it's good practice to keep the low communication, cat5, etc.... and high voltage space 6 to 8 or more inches apart and cross at 90 degrees.........but just to let you know, I've seen the two running together and twisted all together in many a drop ceiling with no issues.

Sorry still not following you on your game plan.
Derating factor......current carrying conductors in raceway 4-6= 80% 7-9=70% 10-20=50%.............Thats the reason why the thhn/thwn stranded wire is used in conduit. the wire in NM is rated as thw. So #12 thhn is rate at 30 amps thw is rated at 25 amps , by time you start useing derateing, you can put more thhn's in the conduit.

Nutty but if you had 4 current carrying conductors in a 3/4 inch pipe those conductors would have to be derated to 80% of its ampacity. If you had those same 4 conductors in a 4" conduit, you would still have to derate them to 80%. Also, running the NM (wire with the jacket around it) in conduit will have a different ampacity value because the conductors aren't able to breath as single wires in the conduit can and your taking up room (internal diameter) in the conduit with all that plastic.

UPS feed with isolated ground. I don't see why you would need that. But I would suggest Balanced clean power. Furman IT 20. Feed it with a circuit and feed all your gear from it. I run all my stuff and several amps from one 20 circuit to the furman. Install the ups and house power to feed the furman and furman to your gear (no clicks pops hummss...silence)(I may put a ups inline with mine someday but currently I've have no problems with outages).
Furman IT-20 II Balanced Power Conditioner IT-20 II B&H Photo

[mpmusicny]

Cool, thanks ritelec,

So (oversized) thhn through multiple (oversized) conduits is the way to go, i think I still need to research the nature of the interface panel into which the UPS outputs would connect, and from which the individual lines head out too the floor receptacle..

The floor is a concrete slab with subfloor resting on what appear to be 2x3 joists - the spaces between the joists insulated with foam. The holes for the conduit will have to be drilled through the joists i fear.

thanks for your advice . .

Malcolm

ps private studio - permits yes, wiring myself, sign off by electrician before inspections . .

[ritelec]

Originally Posted by mpmusicny

So (oversized) thhn through multiple (oversized) conduits is the way to go, i think I still need to research the nature of the interface panel into which the UPS outputs would connect, and from which the individual lines head out too the floor receptacle..


ps private studio - permits yes, wiring myself, sign off by electrician before inspections . .

Nothing has to be "oversized" (unless your running very far away and there may be voltage drop, which I doubt).

Would you really need to try and make use of all the outs of the UPS?
Maybe just take one out that will give you power from the UPS (house power) and switches to UPS power on outage.

permit/you do work/signed off by electrician/inspection.........
how abouts -
Scope work with electrician/permit/you do work/signed off by electrician/inspection.........

[mpmusicny]

ritelec,

your input is very much appreciated.

I had what i think is a moment of clarity this morning. The APC UPS I have is less than $200. It is also silent, at least to these ears, except when it kicks into action during an outage, at which point i don't really care. I will wire the floor receptacle as a standard circuit and have one UPS in the machine room and another by the desk. Beyond anything else, This will avoid a "what the hell is this?" moment with an inspector, and probably look a little better to any future buyer of my house.

Thanks!