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What does the NEC say?

Discussion in 'Landscape Lighting' started by Lite4, Jan 7, 2014.

  1. Lite4

    Lite4 LawnSite Gold Member
    Messages: 3,187

    Can anyone tell me if there is an NEC code listing against running 16/2 back behind a fascia to a low voltage, LED fixture installed in a soffit. The premise would be to power a low voltage fixture in a soffit from a main home run wire running in a gutter. I have never been clear on this and I know it happens all the time. Just wondering if there was a code listed that refers to it in some manner.

    Thanks (see illustration)

    can light in soffit.jpg
  2. Classic Lighting

    Classic Lighting LawnSite Senior Member
    Messages: 512

    I have always been under the impression that any LV wire that enters the structure has to be in conduit. However, I am unsure of a particular NEC listing.
  3. Lite4

    Lite4 LawnSite Gold Member
    Messages: 3,187

    there seems to be a grey area about this. I see LV thermostat wire open, and stapled to roof trusses all the time without conduit. I'll no doubt need to ask an inspector but thought someone here may have crossed this bridge with one already.
  4. The Lighting Geek

    The Lighting Geek LawnSite Senior Member
    Messages: 886

    I believe you are to use a wire rated equal or greater than the circuit breaker on the transformer up to 12" from the fixture. I learned this at the last AOLP seminar about NEC code. We have since changed ALL of our wiring in trees and structures from 16 to 12 accordingly. You don't want to have a cigarette lighter in a structure should the circuit breaker not trip with a partial short.

    I don't know about conduit or not. Bob should know. :)
  5. Lite4

    Lite4 LawnSite Gold Member
    Messages: 3,187

    Thanks Tommy, I wondered about that and it makes sense. I guess that eliminates using any fixtures that have wire leads less than 12/2 (which is pretty much all of them).
  6. Viewpoint

    Viewpoint LawnSite Member
    Messages: 80

    Changing all the wire isn't necessary if you use in-line fuses rated at or below the rating of the wire you're using. Put in an access point (hub or emitter box) with an in-line fuse rated at just above your load, not to exceed the rating of the wire. If you've got 3 LED downlights @ 6w each running on 16ga wire (total load 1.5A), put in a 2A fuse. It's well below the 13A rating of the 16GA wire and will blow the fuse before the wire has a chance to warm up. And it's cheaper than replacing runs of wire.

    This also applies to the fixtures with 25' leads of 18/2 or 16/2. Just fuse it below the rating of the wire either at the hub, or at the transformer.

    Transformers (like many Unique models) without secondary protection should be fused the same way. Great transformers, but technically if the only protection is the 7A fuse on the 120v side of an 840w transformer, you wouldn't be able to use anything smaller than 4GA wire (rated at 70A)! I know no one out there is doing THAT on a regular basis. Especially since you couldn't fit it in one of the lugs on the terminal strip. Simply put your in-line fuse at the terminal strip (or lead wires on older models) and you're covered. No more melted wires. This is the fix I've used on all the systems I've encountered with this type of setup.

    This also goes for any wiring on the structure. Fire 6" under dirt, no biggie. Fire on house, biggie. CYA by using fuses rated at the next size up from your load, as measured with your amp clamp (not calculated...use field-tested numbers).

    As to the wire in gutters, I have heard (depending on the source) that the gutter can be considered an open air chase, and the downspout can be considered a conduit. That may just be because that's what I wanted to hear though. ;)

    Please let me know if/where I got this wrong.
  7. RLI Electric

    RLI Electric LawnSite Senior Member
    Messages: 381

    In regards to the fixture wire question. 210.19(4)Exception@ brings you to 240.5 which is a table of fixture wires.
    20 amp circuit on 18AWG up to 50 ft. or 16AWG up to 100 feet.
    Basically, you are protected by the fact that the lamp limitation of the socket keeps you from overloading a fixture whip. According to the inspector who I spoke with for further description, the fixtures would not pass UL if this was a blatant violation of safety.

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