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Thread: Relay-controlled vs. direct-wired lighting and NEC compliance

  1. #1
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    Relay-controlled vs. direct-wired lighting and NEC compliance

    I'm planning the wiring for a future house and wondering if I can comply with NEC by installing radio- and internet-controlled Sonoff relays at my ceiling and wall lighting outlets?

    This means there will be no wiring to any wall switches, and in fact there will be no traditional switches used to control the lighting in the entire house. Instead a wifi- and rf-enabled relay will be installed at each lighting outlet, and these relays will be controlled remotely. This will enable all lights to be switched on and off via several different methods:

    1- A smartphone app which has the ability to: (1) switch each light on and off individually; (2) switch pre-defined groups of lights on and off; (3) set timers that turn lights on and off on a regular schedule. This control method will work from any location where the smartphone has an internet connection.

    2- Non-traditional "remote control" wall switches that are simply stuck on the walls (with double-stick tape) wherever desired, including typical locations such as near doorways, and in non-typical locations (near the toilet, shower, next to the bed, etc.).

    3- Portable key fobs which send a RF 433Mhz radio signal to "flip the switch" at the correct Sonoff light relay.

    Other than possible NEC non-compliance, are there any reasons why this shouldn't work?

  2. #2
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    Correction: The Sonoff units are not relays, they are remote-controlled switched. Sorry about that.

  3. #3
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    Will this equipment work 50 years from now? Do you want some outsider to control your lights or other loads? Do you want your circuits "jammed" so they do not work? What happens if the Internet is down, or WiFi is not operating?

    .

  4. #4
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    What happens if the power flickers off and on? Will they retain their status, or go to a default?
    If I were going to do this (no way would I) I would put all the controls in one or two locations so if a different technology is chosen later, they can be more easily changed.

  5. #5
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    Interesting thoughts, thanks. I agree with these concerns so here's an alternate question:

    Is it possible (legal) to run 5vdc or 12vdc power via cat5 cable from normal wall light switches to low-voltage relays at my lighting outlets? I would still have to change faulty relays when they fail, but are there other cons to this approach?

  6. #6
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    Consider GE RR type relays. These are bistable electromechanical and operate at a nominal 24 V. Put the relays in gang boxes and not at the fixture. All hard low voltage wiring. Dimmers are a separate issue.

    My RR relays are over 50 years old and I have had few problems.

    .

  7. #7
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    Quote Originally Posted by owkaye View Post
    Interesting thoughts, thanks. I agree with these concerns so here's an alternate question:

    Is it possible (legal) to run 5vdc or 12vdc power via cat5 cable from normal wall light switches to low-voltage relays at my lighting outlets? I would still have to change faulty relays when they fail, but are there other cons to this approach?
    That's similar to what's already been done with the old smart home technology. All your switch legs go back to a panel and cat 5 goes out to all your switch locations.
    If Billy Idol or John Denver is on your play list go and reevaluate your life.

  8. #8
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    Note that the Sonoff does not have a NRTL mark, is limited to 10A, and has already had problems with melting. I would go with a recognized product from a reputable source.

  9. #9
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    When I was taking Robotics/Automation, one lesson I never forget from my professor was: you can do whatever automatic controls that will preclude human interaction, but always consider a certain way to be able to operate something (if at all possible) by going back to the old and time-tested and proven way that took us to the modern world. . . that is, to work it manually.

    This approach is common in avionics where in the event auto control fails there is a way to operate critical operation in manual mode.
    When my house was built (I bought it when it still being built) I got in touch with the builder to install all switch and device boxes that were oversized. My thinking was the same as OP. . .to have lights remotely controlled by relays or wireless.

    I didn't do it at the time because that wasn't included in the price and besides electricians were not trained to do this. Over the years that I've lived in the house I slowly made improvements that include the original concept of using relays and wireless.
    So now, most of my lights/appliances are either remotely controlled or wireless.

    It is still work in progress and my prep certainly paid off. I can switch from auto to manual mode by flipping a custom-wired transition switch.
    No need for an electrician in case any or all of them fail.

    As for NEC compliance...I don't subscribe to the idea that someone's creativity be shacked to limitations imposed by such entity.
    I've been trained to do things safely enough. I do use NEC reference in case ambiguities arise.

    Just my two cents.
    Last edited by myspark; 12-06-17 at 08:14 AM. Reason: Paragrahing

  10. #10
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    210.70 requires at least one lighting outlet that is wall switch controlled in habitable rooms and bathrooms. Occupancy sensor exception still requires manual override ability.

    I think most would want to have manual override or at least additional manually operated options for lighting.

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