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I've just had a holiday lights company install some outside tree lights, and I found they had done it so that at several places the prongs of mains cable plugs had been left exposed, and carrying mains voltage. I've put a couple of pictures here: https://tinyurl.com/tk-wiring-pics (In the one with the voltmeter, that plug is just as it was left lying on the grass by the installer -- I didn't have to unplug it to get to the pins.)

enter image description here enter image description here

Is that permitted under the US NEC?

I know there is provision in the NEC for temporary (up to 90 days) installations, and the installer has told me that their setup is fine because of that. But that sounds a bit dubious if it implies you can leave 100V+ lying around in the grass for some kid to stand on.

Also, I think I found the reason it has happened, and that is that the installer has made up some of their own cables, and one of them has a plug at both ends (i.e. instead of a plug at one, and a socket at the other). As a result they have in a sense "reversed the direction" of plug-to-socket, and so instead of the usual power going into plugs and out of sockets, they have a big section of our yard lights where power is going into sockets and out of plugs (several of which are then exposed to the outside).

Seems very unsafe to me but, again, is that actually allowed by NEC under the temporary installation allowances?

JPhi1618
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tkp
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    I don't know enough to cite the NEC, but I'm pretty sure exposed, live, high voltage wires are never allowed for any amount of time. They're just being lazy, and they need to fix this ASAP. All the splices in that home-made cable need to be covered too so start looking for loose wire twisted together. – JPhi1618 Dec 15 '17 at 17:34
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    I agree, and since writing the above I've established that NEC section 590 is the relevant one. It seems quite clear that while many misunderstand this, it is not a shortcuts list. It provides for a couple of small relaxations in the use of NM and NMC cable, but other than that it's mostly saying that just because the installation is temporary doesn't mean you can ignore code. I'd still like to hear something definitive from someone who's up to speed on NEC 2017 though. – tkp Dec 15 '17 at 17:38
  • If they're plugged into a GFCI (they should be) that kind of stuff will cause the GFCI to trip with just a little moisture.... Dew, rain, snow,etc. It's very sloppy work. Nothing protects unsafe installations, even if they do fall under the 90-day temp rule. – Tyson Dec 15 '17 at 18:12
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    Seeing the second pic, I get it now... They are out of clamp on female plugs, so they are using male plugs to feed piggy back plugs. No this is NOT acceptable and is unsafe. – Tyson Dec 15 '17 at 18:23
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    why even have the clamp on connector, a couple wire nuts would be safer than this. – Jon Dec 15 '17 at 18:48
  • Have they finished the job and left it like that?? – agentp Dec 15 '17 at 18:58
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    Holy cow this is totally illegal for any and I mean any install in the U.S. there needs to be a socket not a plug to provide power to additional strings. 590.5 states the holiday lighting shall be listed and labeled, there is no way this is a listed product. – Ed Beal Dec 15 '17 at 19:20
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    I don't think the NEC or UL or any regulation is at all relevant for this one. It's a live, exposed hazard that could kill pets, children, or careless adults... even if the company could justify it under some loophole in the NEC, you would still be liable when it kills someone. – Robert Nubel Dec 15 '17 at 19:33
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    As if accidentally leaving something like this in place isn't bad enough, they lied and tried to tell you it was acceptable to leave 120V exposed. These installers are incompetent and deserve to be bankrupt. – Jonathon Reinhart Dec 15 '17 at 20:31
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    (basing on info provided in OP) KEEPS THOSE LIGHTS OFF!!! I have no words to describe what a f**** reckless job this is and have no idea how can someone sleep at night knowing he made it. Really. It can EASILY be cause of DEATH. And if you (and this is perfectly legitimate) have not enough DIY experience to realize this yourself my invitation is to call a certified electrician ASAP and even evaluate if to report whoever did this job to relevant authority. A kid picks that thing up and is dead. – Caterpillaraoz Dec 15 '17 at 23:58
  • Yes. Temporary installation or not, that could end up with someone temporarily in hospital or permanently in a grave. – rackandboneman Dec 16 '17 at 13:30
  • Thanks all. Very useful answers and comments. By way of update: the company did agree to fix the problem but without ever accepting it was a problem. Instead they said they'd replace it "if it makes you feel safer". Then, in a final act of silliness, when they did replace their dangerous home-made cable with several that were clearly shop-bought and well-designed, unfortunately they used one that had had its plug's earth pin sheared off. Of course since most of the installation was two-core and earth-less, that wasn't a problem in itself (although again, it may be out of code). (cont'd) – tkp Jan 03 '18 at 22:10
  • (cont'd from previous) Of course since most of the installation was two-core and earth-less, that wasn't a problem in itself (although again, it may be out of code). But since that missing earth pin essentially meant the ostensibly earthed cable had become unearthed one, I'd have at very least liked to see some really obvious warning so that no one would mistakenly use it in a different setup where an earth was in fact necessary. No such warning was given, adding to my overall suspicion that these guys know little or nothing about electrical safety. (cont'd) – tkp Jan 03 '18 at 22:13
  • (cont'd from previous) No such warning was given, adding to my overall suspicion that these guys know little or nothing about electrical safety. So it seems fairly clear that what I've experienced was not simply an unfortunate slip, but rather was part of a systemic lack of capability. Because of that, I now feel kind of obliged to report this to some authority, purely to help try to avoid it happening to someone also who might know a lot less about this stuff than I do (and I myself am no expert). Trouble is, it's not at all clear to whom, or how I should make that report (I'm in Austin, TX). – tkp Jan 03 '18 at 22:17
  • @Ed Beal (and others), thank you. Even though I've now read the most obviously relevant parts of the code, I couldn't figure out what the term "listed" meant. From what you're saying, it seems that what these guys did was not out of code only because their home-made cables were dangerous (since they would lead inevitably to a setup with exposed conductors). That I already suspected and it was what triggered my question. But what you guys are saying is that the company were also out of code purely because their home-made cables were indeed home-made (i.e. and not also listed). Urk! – tkp Jan 03 '18 at 22:35

3 Answers3

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You are correct in assuming there should not be any live connections exposed in any situation. I suppose it should be said that this is a dangerous situation and could be fixed fairly easy with a set of wire cutters and some appropriate wire nuts. So call the installer and see if they want to make the repair. If they give you any static I would report it to the AHJ in you area and let them deal with it.

Regardless I would not recommend you turn these lights on until a repair was made. As I said before this is a potential fire and shock hazard.

Retired Master Electrician
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    Chances for recourse are probably slim with a fly by night "holiday lights company". Worth a shot I guess though, but I wouldn't have these people back on my property even if they paid me to be there. – Mazura Dec 16 '17 at 01:42
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It's incorporated by reference. The electrical code cites 110.3

listed and labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

Which punts the entire matter over to UL.

Let's test the theory that this is legal. They either bought this item off the shelf, or they modified it themselves.

If they bought it off the shelf -- then UL would have had to test, approve and list the cable with male NEMA 1‘s on both ends. I think we can reject that as highly improbable.

If they modified it -- then they would need to be doing so in accordance with instructions to do so, these instructions being approved by UL as part of the testing, approval and listing of that product. Now, can you imagine UL approving instructions that advise or fail to prohibit attachment of a male connector in more than one place? I am not a product manufacturer so I don't know the guts of the UL rules, but I don't see that happening.

Realistically, they modified it gypsy/illegal, which violates 110.3.

As a practical matter I would buy a bare NEMA 1 socket for about a dollar, and slip that over the bare contacts, tape it down with electrical tape (to make it obvious this should not be taken apart) and call it good. That is so stupid-easy I cannot believe the installer didn't just do that. Don't lop off an extension cord to do this, as the cut end will have hot and neutral about 1mm apart and could burn little fingers. Or big ones.

Harper - Reinstate Monica
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    Whoever did this should be reported to the local building department and Better Business Bureau if they don’t immediately fix it. – Mark Dec 15 '17 at 19:47
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    I once bought a rope light (for personal use) that had a male connector at both ends; I'm pretty sure it was just a manufacturing defect. Since I bought it during an "all sales final" January closeout, I popped the fuse from one end and confirmed that disconnected the hot prong, and then wrapped the whole thing in electrical tape. The fact that there's a male at both ends wouldn't imply the installer modified it themselves, but I don't think ignoring an obvious manufacturing defect is really any better. – supercat Dec 15 '17 at 20:15
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    In this case the company actually told me they had built the cable themselves. They said they were "home made" but I misheard them, thinking maybe they'd used a technical term meaning "cable with multiple plugs". So I asked them to repeat it and the guy said more clearly "H-o-m-e M-a-d-e; you know, we made it ourselves." And in fact there were two such home-made cables: one had a male at both ends; another, while having a male at only one end and a female safely at the other, also had 5 or 6 males along its length, as "tapping" points. So I had roughly one live exposed plug per tree. Ahem. – tkp Jan 03 '18 at 22:25
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Combined my comment and answer since the OP asked about NEC rules and holiday lighting .

Not legal at all!!! 406.7.A , in short says NO exposed current carrying conductors totally illegal this could never be listed! 590.5 states the holiday lighting shall be listed and labeled, there is no way this is a listed product.

Ed Beal
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    "Jumping to 406.7, we find there is a central theme to each of the specific paragraphs in this rule. The message here is that at no time will the exposed prongs of an attachment plug or flanged inlet be energized, unless properly connected to a receptacle or connector body." (and thus, no longer "exposed") –iaeimagazine.org – Mazura Dec 16 '17 at 01:58
  • IMO, this Q isn't in the purview of the NEC, but the company opened up that box themselves. I think they meant that because it's not permanently installed, they don't (have to adhere), which is true, but that doesn't make it permissible in the real world. “contractor will perform its work in a good and workmanlike manner.” that's the part they violated, if it's applicable in the first place - but you don't need a permit to hang Xmas lights, so... – Mazura Dec 16 '17 at 02:02