I know the wall occupancy sensor wont work properluy without a good ground. I have bathrooms and 2 separate OS switches with ground attached and I went back to search each J box leading up to switch but I cant find anything loose. If I attach to neutral I can get them work come on but not function with mottion. I have power and ground connected to each OS switch but its not working properly. I have installed these OS switches before but I assume its a wiring problem because its happening to both at same time. Does everthing the switch is operating also need to be properly grpunded also? I havent checked that yet. Basically I can get OS switch to work with ground but I can get it to function with neutral.
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wall occupancy sensor not working
- Thread starter mannyb
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gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
191004-0944 EDT
mannyb:
You need to play with things, experiment, and take them apart. Learn how complex devices you work with function.
A motion sensor contains some circuitry to sense motion, some timing function, and some output device to switch the load.
The circuitry in the device needs power to operate.
Your device likely has three wires, excluding an EGC. You refer to ground. What does ground mean? It should mean EGC, and EGC is not where you should derive power from, but some manufacturers do.
These three wires would be the hot (ungrounded power lead), a grounded power lead (you may call this neutral, and possibly shouldn't), and the switched power output wire. If the box is metal, then an EGC should connect to it. Your load (light) to be switched will be between the switched power output lead, and the grounded power lead.
The electronics in a motion sensor requires some small amount of power to operate. Where does this come from? The two power input leads. Some manufacturers used the EGC instead of a grounded power wire, because of the small current required, and many times existing switch boxes don't have any grounded power wire.
Take one of your motion sensors and test it on the bench. Apply power to the two input leads, and a 100 W incandescent between the output lead and the grounded power wire. Does the motion sensor work? If so the motion sensor is probably OK.
What kind of power switch is in your motion sensor? If electromechanical, then it will click when the state changes. If solid-state you won't hear anything. An electromechanical switch (an ordinary relay) should switch virtually any kind of load within its rating. Solid-state may not.
If you are depending upon the EGC conductor for the grounded power lead source, then you need to know if it really is grounded. The simple way is to measure the voltage between the hot input to the motion sensor, and the lead that should go to the grounded power wire. If this is anywhere above 90 V for either state of the sensor, then I think you have adequate power to operate the sensor.
If in your application the load is not an incandescent, then add in parallel a temporary 100 W incandescent, and see it it works.
.
mannyb:
You need to play with things, experiment, and take them apart. Learn how complex devices you work with function.
A motion sensor contains some circuitry to sense motion, some timing function, and some output device to switch the load.
The circuitry in the device needs power to operate.
Your device likely has three wires, excluding an EGC. You refer to ground. What does ground mean? It should mean EGC, and EGC is not where you should derive power from, but some manufacturers do.
These three wires would be the hot (ungrounded power lead), a grounded power lead (you may call this neutral, and possibly shouldn't), and the switched power output wire. If the box is metal, then an EGC should connect to it. Your load (light) to be switched will be between the switched power output lead, and the grounded power lead.
The electronics in a motion sensor requires some small amount of power to operate. Where does this come from? The two power input leads. Some manufacturers used the EGC instead of a grounded power wire, because of the small current required, and many times existing switch boxes don't have any grounded power wire.
Take one of your motion sensors and test it on the bench. Apply power to the two input leads, and a 100 W incandescent between the output lead and the grounded power wire. Does the motion sensor work? If so the motion sensor is probably OK.
What kind of power switch is in your motion sensor? If electromechanical, then it will click when the state changes. If solid-state you won't hear anything. An electromechanical switch (an ordinary relay) should switch virtually any kind of load within its rating. Solid-state may not.
If you are depending upon the EGC conductor for the grounded power lead source, then you need to know if it really is grounded. The simple way is to measure the voltage between the hot input to the motion sensor, and the lead that should go to the grounded power wire. If this is anywhere above 90 V for either state of the sensor, then I think you have adequate power to operate the sensor.
If in your application the load is not an incandescent, then add in parallel a temporary 100 W incandescent, and see it it works.
.
The OS switch has line load and an EGC on device. I have power but I was told it needs to be properly grounded to operate. I traced the ground all the way back to panels and xfmrs and I located a bad connection inside the xfmr and also discovered they didnt install bonding inside the xfmr. This actually was the problem the devices now work. I figure the small problem was part of a bigger problem up stream
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