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AssuredElectrical
AssuredElectrical, Master Electrician
Category: Electrical
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Experience:  Contractor-42+ Years in the ElectricalTrade
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Adding an occupancy sensor to a 3-way circuit. Manufacturer

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Adding an occupancy sensor to a 3-way circuit. Manufacturer did not supply any diagram for 3-way wiring. Occupancy sensor has 4 leads - ground, neutral, hot and load. Have seen some other manufacturer diagrams with similar sensors that are able to be wired 3-way. Ultimately need two things - need help figuring out which wire lead in house is load side and want to wire the occupancy sensor so that it turns on the light at any time, but the other 3-way switch can override it as "on" full time when turned on. Should be fairly simple, but I always get confused with3-way switches.

AssuredElectrical :

Hi, Welcome to Just Answer. My name is XXXXX XXXXX would be glad to assist.

AssuredElectrical :

What is the make and model of the sensor? With only 4 leads, sounds like a single pole and not a 3way.

Customer: Yes, I think it is a single pole.... Intermatic iOS-dpbif-wh.
Customer: Worst case scenario, I have no prob
AssuredElectrical :

let me look it up

Customer: Oops...I have no problem giving up the 3-way to install the occupancy sensor as standalone. Just have to figure out how to use the existing 3-way wiring (or how to undo it). This is for a garage, by the way.
AssuredElectrical :

ok

AssuredElectrical :

it is a single pole, so we need to get some more info on your wiring

AssuredElectrical :

At the location you wish to install this sensor, how many wires in the box? and what colors?

Customer: I have a multimeter and am pretty mechanically inclined. The box is a double gang box,there are 2 3-way switches in there for 2 different circuits. It is a basic 3-way circuit from all appearances - there is only one set of runners (black/red) going to other switch (near side door in garage, attempting to replace main switch which is by door into house with occupance sensor).
AssuredElectrical :

At the location you wish to install this sensor, how many wires in the box? and what colors?

AssuredElectrical :

all wires connected to the switch you are replacing and any wires that are in the same cables as those that attach to the switch

AssuredElectrical :

3 ways have 3 terminals, one black screw and 2 brass

AssuredElectrical :

need wire color on each

AssuredElectrical :

and at each switch

Customer: okay, on the main box (where I want to replace with occupancy sensor), there is a toggle switch with a brass and black terminal on one side and a brass terminal on the other side. the black screw is connected to the hot (black wire) and the brass screws, one on each side, are connected to a black and red runner that goes into the same sheathing/romex up the wall. on the side door of the garage, the switch is wired with two red wires and a black. the black and red that come from the same romex are wired to each side of the brass screws on that switch. the 2nd red wire is wired to the black screw.
AssuredElectrical :

ok, thanks

AssuredElectrical :

now, the whites that are in the same cable as the red and blacks, are they just connected to other whites in each box?

Customer: yes, all the neutrals are connected to the other neutrals in the box
AssuredElectrical :

ok

AssuredElectrical :

Switch you are replacing------The sensor Hot wire connects to the Old switch Hot (black screw). The sensor white connects to the the group of whites in the box (neutral). The ground of course connects to all the other grounds, and the sensor Load connect it to the red going between the 2 switches.

Customer: if you could please, when you get to giving a final answer/explanation, I use all of this as part of my learning process... if you could explain which is which is I can understand it from a reverse-engineering perspective (I am going to have to do this process again, but in reverse for a timer that I need to install), it would be much appreciated
AssuredElectrical :

If you will read what I posted

Customer: yes, got it -- makes sense
AssuredElectrical :

Ok.

AssuredElectrical :

Now, the other switch that will no longer be used

AssuredElectrical :

connect the red that goes between the 2 switches to the red on the black screw

AssuredElectrical :

Then cap off all the other on the switch

Customer: ok, so I am going to assume then the red lead that is by itself in the 2nd box is the lead that goes to the load, correct?
AssuredElectrical :

The red that is on the black screw is the load to the light

Customer: the one that I am going to connect to the runner from the 1st switch
AssuredElectrical :

correct

AssuredElectrical :

you are just connecting it all the way back to the sensor load wire

AssuredElectrical :

on 3 ways, the black screw will either have power or the light. You identified which one had power, so the red is to the light at the other end

Customer: ok great.
AssuredElectrical :

that is why it is identified, it is called the Common

AssuredElectrical :

The other 2 brass are called Travelers

Customer: ok, so I take it this is obviously standard in the electrician's world.. the black screw is either from the hot (power source) or wired to the load, correct?
AssuredElectrical :

correct. But dont think it is always that easy. Sometimes all the wires are in the same box. Then you send the power to the last switch and back again

AssuredElectrical :

There are many ways to connect the wires, but end result is---power on one switch black screw and the light on the other ones black screw

Customer: oh boy. yes, I've studied the diagrams... it all depends on where the electrician who installed placed the load... either inbetween the 3-way circuit or off of one or the other. thanks for the help -- sounds pretty straight forward.
Customer: if I could slap the guy who installed at this house, I would - he hooked up the garage and labeled it "cooktop" at the panel
AssuredElectrical :

You see mis labels all the time, here is a way to do a proper circuit directory on a panel

AssuredElectrical :

Full Size Image

Customer: just moved into existing house, 7 years hold, been here 1.5 months... obviously trying to have my way with the house. prefer occupancy sensors in places like the garage, timers on the outdoor lights, etc. have always manage to do fine on my own, but this house was built with about 10+ 3-way circuits... drives me NUTS!
AssuredElectrical :

they can be fun and sometimes down right tough

Customer: this info is going to go a long way for me :)
AssuredElectrical :

great,

Customer: appreciate the lesson :)
AssuredElectrical :

You are very welcome. Glad to be of service. If your are satisfied with my
assistance to your questions then, please do click the Accept for my time.

Customer: will do, have a good afternoon...
AssuredElectrical :

you too

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