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I currently have an armored cable 12/2 with green (ground) leading to a light switch, running outside the wall (simply runs from the light fixture to a surface mounted box where the light switch is). I will convert this light switch to an outlet light combination. That means I need a 12/3 cable. Unless for some reason I'm able to use the green as a neutral or hot return.

In case I really need a new cable (12/3): I assume I can't use NM cable. This is a New York city 13-floors building built in 1965. Correct? I've found Service Entrance Wire, Portable Power Cord and Armored Cable. It's unclear to me the specific purpose of the SE Wire and Portable Power Cord. It seems a little hard to find Armored Cable 12/3 - for some reason they are not cheap as 12/2, so that's why I looked into other options.

Any insight is appreciated, thank you!

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  • Your cable is metal-clad cable, not armored cable (MC, not AC), BTW Apr 16, 2020 at 1:12
  • Does power come in at the light switch or at the fixture? Apr 16, 2020 at 1:13
  • @ThreePhaseEel Power come in at the light switch. How do you know it's MC, not AC? It's very hard for me to distinguish them and my research showed it is AC based on looks and general availability.
    – igorjrr
    Apr 16, 2020 at 1:38
  • It's MC because it has a green ground wire in it -- the only time a green ground wire is found in AC is if you are looking at HCF-AC cables used for hospital wiring. Apr 16, 2020 at 1:47
  • @ThreePhaseEel Wow, didn't know that, thanks! Funny that a large home improvement store labels Armored Cable both AC and MC. Maybe MC is a subset of AC...?
    – igorjrr
    Apr 16, 2020 at 1:50

3 Answers 3

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Portable power cord is for appliances. You know it from every plug-in appliance you have ever owned. It is illegal to use in installed wiring (NEC 400.8).

Service Entrance wire is for connecting services from the transformer to the electric meter in places that are not NYC.

You can use armored cable, FMC flexible metal conduit, EMT hardshell conduit, IMC or Rigid pipe-threaded conduit. Your call. If it is surface mounted, I find EMT generally provides a more elegant installation. The stuff is a learning curve, but it's real nice when done.

As an NYC dweller, there is no reason for you to own any kind of non-metal cable: not NM, not UF, not SE anything, not MH. The only wires to own are AC and THHN.

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  • Thanks! When you say "as an NYC dweller" you say based on the electrical code for the city? Or a personal opinion (mixed or not with code)?
    – igorjrr
    Apr 16, 2020 at 1:41
  • Another question: I'm surprised you find EMT more elegant. I find armored cable better since it comes with all the wires and is thick enough just for it, no wasted space. Would you be able to provide some points why you find EMT better than armored cable? If this is running long wires across living room (for example) then I agree EMT has more a "serious"/elegant look. Only because armored cable is not plain/smooth (but flexible and better to work in specific installations like mine). I can always cover the armored cable with a cable cover and paint. Any thoughts? Thank you!
    – igorjrr
    Apr 16, 2020 at 1:47
  • @igorjrr I have always liked EMT over armored cable. As far as elegant, EMT just looks better exposed. It's straight, doesn't sag between supports , actually looks like a work of art when done correctly and can be easily painted. As far as more practical, it's way cheaper to install and pull wire than armored cable is. If you need to add a wire, you just pull it in the EMT. If you had EMT installed, you'd be spending a few bucks on wire instead of replacing the entire run. Just my humble opinion.... you stay safe out there.
    – JACK
    Apr 16, 2020 at 12:59
  • @igorjrr Because of NYC electrical code. Armored cable always looks chunky like it's squirming up the wall. Gives "inside of a Borg cube" vibe. But I guess that's an aesthetic choice. Obviously it's easier to install, but also less versatile. Apr 16, 2020 at 21:15
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First off, you can not use the green, ground, wire as a neutral. You are right about not being able to use NM cable in NYC. It is allowed in certain residential applications in other parts of NY but not in the city. 12/3 with a ground armored cable is what you need. Most home stores will sell a 25 ft reel. 14 gauge wire is also not allowed in the City so don't try to bring some in.

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  • Is DIY electrical work even allowed in NYC?
    – jwh20
    Apr 15, 2020 at 21:51
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Assuming there is a switch controlling the existing light, eliminate that switch and just connect the 12/2 straight to the new light + outlet, then put a new switch out there by dropping a piece of conduit straight down below it to another surface mount box..

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