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I can't even tell if this is a stupid question anymore.

I have a desk in the center of a 12′ × 13′ room, on which I would like to have a power strip to power a computer and other, less power-hungry devices. After my first, definitely stupid and dangerous idea (to run an extension cord under a rug), I started looking into the NEC and the UL White Book and the difference between "relocatable power taps" and "multioutlet assemblies" and now I feel like I have no idea what is safe.

Here's what I think I know:

  • Extension cords are not to be used as a replacement for permanent wiring. I want this setup to basically stay in place for the next one to five years, so extension cords seem to be out.
  • A power strip—erm, "relocatable power tap"—can maybe be used as permanent wiring if it contains a fuse or circuit breaker and if no tools are needed to remove it. But it still can't do things like go in walls (I'm a renter; I'm not looking to break through any walls anyway).
  • "Flexible cords" (which includes the cord of an RPT?) must not be attached to "building surfaces." (But does that prohibit attaching cords to walls/ceilings using hardware designed for this, like cable staples large enough not to put pressure on the cord, or ceiling hooks like what I see used with lamps sometimes? Neither of these methods require tools to remove; is that relevant?)
  • Power cords should not be covered because they are designed assuming they can be cooled in the open air. (But does that prohibit floor covers like this, or raceway sections like this?)

I should also note that my computer has a 1200W power supply, and while I've never actually measured it using nearly that much power, to have a margin of safety, I want to assume that it could basically start drawing 10A at any time. Therefore, whatever powers it should both be rated for that level of current (ideally the full 15A that the room's circuit can provide) and also be installed in such a way that resistance heating in the power cord isn't a fire hazard.

So it seems like I have three general approaches:

  • Run a power strip with a circuit breaker and a long power cord across the carpet up to my desk. Try not to trip on it. There is a virtue in simplicity, but hey, everyone trips sometimes.
  • Same as above, but cover it with something safely (i.e., by means that prevent tripping, damaging the cord, and up-to-15A currents causing anything to heat to an unsafe temperature). I'm not a huge fan of the floor cord protectors I've seen (they seem like they'll be obnoxious to move when vacuuming), but if it's the right thing to do, I'll do it.
  • Run a power strip with an even longer power cord (I'm looking at this one) up the nearest wall, across the (drywall) ceiling, and drop down onto the desk. Barring electrical issues, this is my favorite approach, but it leaves me with a lot of questions about whether there is a code-approved (or not technically code-approved but still assuredly safe) way to affix a power cord to walls and ceilings. The codes all seem to forbid this generally but things like that Wiremold raceway and ceiling hooks for lamp cords seem to indicate otherwise (and if those are safe, I don't see why appropriately-sized cable staples wouldn't be also). If the Wiremold raceway is the way to go, I also can't tell if there's a meaningful difference between just covering the power strip's existing cord with raceway versus doing a more extensive Wiremold installation, which seems to involve tapping into an outlet with a starter box, running a different kind of wire through the gateway, placing a receptacle... on the ceiling? And running the power strip down from the ceiling receptacle? Is that actually safer?

What should I do, and which of these various questions and concerns are actually safety issues versus misunderstandings or excessive pedantry?

(If relevant, I live in Connecticut, USA.)

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  • Is this a floor where you have access from below? Possible to add a circuit leg to a floor mounted outlet? – DaveM Aug 8 '20 at 18:27
  • @DaveM I'm a renter; modifying floor, walls, or ceiling beyond surface-mount stuff is right out. – hlim Aug 8 '20 at 18:32
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Appliance and extension cords are called cordage.

Use the right stuff

The issue with cordage as a substitute for permanent wiring of the structure is not a “don’t do it” issue: it’s a “use the right stuff” issue.

“The right stuff” is appropriate wires designed for permanent use in structures, including appropriate physical protection. For instance instead of stapling cordage to a wall, you should use surface conduit with THHN wires inside.

Of course, that requires a transition from the THHN to the cordage at some point. That happens at a junction box, e.g. with a receptacle in it; the easiest way to transition from hardwiring to cordage.

Consider a pendant for center-of-room power

A pendant is a piece of special cordage with high quality strain relief on both ends (think the Chinese finger puzzle webbing) that drops straight down from a box on the ceiling down to a junction box suspended in midair by the cordage. You then plug into that recep.

Probably best to use a fan-rated ceiling box. This can be a surface-mount box (you’ll need to find the studs) which in turn can be supplied via surface conduit such as Legrand Wiremold.

The suspended box would probably be a metal box rated for a fan, since they are tough and built to endure tugs on the pendant.

If you want to be very fancy, you can have the pendant lock into a locking connector like a NEMA L5-15.

That PC power supply is a terror

That “1200 watt” PC power supply is a gigantic beast made for gaming. The “1200 watt” figure is the actually useful DC output of the supply; it is NOT the AC mains input — that is affected first by the efficiency of the unit and by the power factor.

   X (actual power drawn) x efficiency% x PF% = useful power out.  

The “850 watt” power supplies actually draw 10 amps. So I could see a 1200 watt supply drawing 16A or 17A.

I would revisit the necessity of such an ostentatiously large power supply.

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  • What makes cordage not appropriate in this case? Is it a safety issue or something else? I could imagine, say, that electricians use THHN because it's thinner or cheaper than cordage of the same ampacity, maybe because cordage has to be made idiot-proof in a way that concealed wiring does not. I'm just not sure how concerned I need to be about doing this the way an electrician would—ultimately what I actually care about is being safe. If a cord on the floor is less safe than a cord draped over a nail in the wall, but the nail in the wall is technically a code violation, I'll go with the nail. – hlim Aug 8 '20 at 22:07
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I would use a cable protector.

It is true the NEC doesn’t want cords used for permanent installs but a movable desk is really not permanent even though it is going to be there beyond the 90 day temporary rule. I would use something like Electra duct a plastic ramp like cover to protect the cable and prevent tripping. There are many other types like, pedestrian cable covers, and durable cable ramps. I just searched for power cord floor covers. And found the above examples.

In commercial facilities they use a hard wired version that has the cord covers for both power and data the only difference is there is a box extension to connect the assembly that then goes on the floor to the wall sections.

As your desk is not a permanent fixture even though being in place more than 90 days the cord protector should be fine for your use I would suggest a heavy 12 awg cord since you plan on a heavy load, if you have a 15 amp breaker 14 awg would be ok.

The place I normally see problems is at the receptacle where a cheap $1.00 contractors grade receptacle is used and possibly back-stabbed.

A spec grade receptacle like a back and side type using the clamps would be better. These receptacles have better contacts and a higher withdrawal force reducing overheating problems at the plug.

The last thing I thought of was a 90 degree cord cap this replacement plug plugs in like normal but the wires exit at 90 degrees to the wall so there is no side force on the contacts. I use these in offices for this reason and when the office personal move things around these hold up to something being pushed into them breaking the receptacle and plug.

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  • You don’t get charged for carriage returns on here... – Solar Mike Aug 8 '20 at 17:35
  • How do I tell if the cord protector is safe for a cord carrying 15A? I thought part of why cords can't run under rugs is because they need to be air-cooled, especially at higher loads; many of those cord protectors don't look like they would give a 12 gauge cord much breathing room. Any thoughts on the wall/ceiling mounting approach? Is that just a bad idea in your opinion? – hlim Aug 8 '20 at 17:46
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    If you look at cordage it has a higher ampacity than the same size nmb. If you look at what 14 awg is ok for in a residence just look at the * and references reducing the capacity of 10, 12& 14 gauge wire being limited but in a control panel the values are 6 to 10x as high so will there be a problem NO , as I said the connection is the problem not the wire 14 awg in a control panel tops many times higher than the breaker value if the wire is protected as the devices I mentioned. – Ed Beal Aug 8 '20 at 19:45
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Posting this as an answer to be able to use an image, but this is what Ed Beal was referring to (concept, not the brand). Lower picture is what it looks like flipped over, showing the track that the cord snaps into.

enter image description hereenter image description here

You can get them at office supply stores or on-line.

The Code is for premise wiring that would stay with the building when you leave, not how you set up and use things while you are there.

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  • Yup, I've seen these. Maybe this should be a separate question, but I need to know if they're really safe for cords that will be carrying up to 15A. As I understand it, the reasons for not putting cords under rugs are two: foot traffic can damage the cord, and the cord can overheat. These protectors look designed to address the first, but are they better than rugs with respect to the second? I know we're probably only talking about 10W or so of heat (for 10 ft. of cord containing two 14 gauge conductors carrying 15A), but if it's an issue for rugs why wouldn't it be an issue for these too? – hlim Aug 9 '20 at 13:32
  • @hlim PVC insulated cable can stand 70C (about 158F) for hours on end. If the cord doesn't feel hot, it's fine. – Simon B Aug 9 '20 at 15:59
  • As I understand it the issue is not really heat, you can't legally put extension cords under rugs and carpets because you cannot see them to inspect them for damage, i.e. the insulation wearing through. With these, you can just flip it over to check the cord. Not that anyone really does that, but thems the rules. – JRaef Aug 11 '20 at 22:43
  • Also, you CAN get what's called "FCC" wiring (Flat Conductor Cable) to go on floors and under carpet, but even then, it's approved for use under carpet SQUARES,ostensibly because you can remove the carpet squares to inspect the cable. It has to have a metal shield over the top of it (under the carpet) to protect it from physical damage. Hardly anyone uses that though, too many conditions of use. – JRaef Aug 11 '20 at 22:44

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