New Electrical Question!


Old 02-05-01, 09:00 AM
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I picked up a real nifty motion detector light switch for the garage. That way I can drive in to a lit garage, instead of getting out and fumbling for the switch (eventually I'll get a garage door opener, but that's way down on the to-do list). Well, the switch that is in the garage is a double plate that also has the switch to turn on the outdoor light.
When I carefully looked at the wires, the hotwire for the outdoor light has some insulation peeled back, looped around the screw of the garagelight switch, and then it goes on to the switch for the outdoor light. This is I'm assuming to make the outdoor light go on when the garage light is turned on, but it seems rather risky to me.

Does this sound safe to any of you? Or should I wrap that up with electrical tape and continue with installing my motion detector (which I want far more than my outside light to turn on)? Please advise.

PS. Can you tell I'm a new homeowner??? Thanks!
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Old 02-05-01, 10:58 AM
Join Date: Sep 2000
Location: Fayetteville, NY, USA
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Hi Jen. No, I couldn't tell at all that you were a new homeowner. And I won't tell anyone else.

First we should define out terms. If you bought a motion-only switch then it can only be used indoors in a heated area. Shouldn't matter if it gets chilly for a moment when the garage door opens, as long as it is normally even luke warm in there. These things will mess up if installed where it's normally cold.

If I have presented any conflicts with the one you bought, you will need a combination motion/photo cell switch. I installed this type on the outside of my garage and it turns on the outside spot, inside light in the garage, and the light over my rear entry to the house (detached garage). It lights everything up when we pull into the driveway. Really handy thing to have.

Anyway, from that you can decide if you have the right switch type.

As far as you existing wiring status, this isn't properly done. I believe the person who wired this switch system is powering both switches from one "hot" wire, then a second conductor on each switch goes to each separate light system. That second wire is dead when the switch is off, the other one is live all the time.

Normally you should have a power wire coming in to the switch box. This is the main incoming power wire, and should be black usually. Here's where a volt meter comes in handy. Anyway, onto this one black wire there should be two black wires approximately 10" long, one going to power up each of the two switches. This group of three wires is called a "pigtail". Then a second wire on each switch goes to each separate light system.

I hope that makes sense. If it operates correctly right now, and one switch turns on the inside lights and one switch turns on the outside lights then it's functionally wired right, just wrong method. With the power off disconnect that funky wire that is attached to both switches, and connect the two 10" pieces described above, then connect one to each switch on the same screw the old funky wire went on.

If you think you need a motion/photo switch instead, post a reply and we'll help you hook it up. Good luck Jen.

Old 02-05-01, 04:36 PM
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Question Answers and more questions

First question, the garage stays the same temp all the time (chilly). It's not insulated and so the outside temp is about the inside temp. The detector is motion/temp, but it should be fine.

I'm not sure I explained the switch in the best fashion.

There are two switches on the plate. Both have wires going into them. However, the hot wire for the outside light makes a detour, loops around the switch for the interior light, and then proceeds to the outside light switch. The interior light's wires go into the back of the interior light switch. If you removed the outside light wire's curve around the screw on the interior light switch, it would be all normal and fine. It's seems they tried to make the outside light hot wire do double duty.

I wish I could draw this, but does this make sense?
Old 02-06-01, 10:35 AM
Join Date: Sep 2000
Location: Fayetteville, NY, USA
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Still not entirely clear. I think you mean that you have only one hot source wire in that double box that holds the switches. They used that funky looping technique to run two lighting curcuits off a single incoming hot wire instead of pigtailing as I previously described. Basiclly a regular (not 3-way) switch has an incoming power wire and an outgoing wire to the fixture(s) which is dead when the switch is off and live only when the switch is on. Do you follow that?

It doesn't make sense to me when you seem to say that each switch has its own 2 wires PLUS the outside switch sends yet a third wire to the inside switch. And I'm further confused when you say that if you removed the looped wire between the outside switch and the inside switch that everything would work fine. Wouldn't you be removing the power supply from the inside switch?

Please reply and we'll talk further.


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