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fowlkesfamily 12-20-2012 09:10 AM

House Ground not strong enough
 
I installed an occupancy sensor in my laundry room. The light stays on continuously. After verifying that I had all wires correctly spliced and insuring that the ground from the sensor was run to the metal outlet box, I called the technical support (for the product). The technician verified my wiring connections. Then he told me that the reason the sensor would not shut off is because my house ground is not strong enough. I've been reading about house grounding problems, but have not found a good solution. I think I need to improve the ground connection which is located outside near the fuse box, but I do not know how to do that.

oh'mike 12-20-2012 09:25 AM

This sounds like you don't know a lot about household wiring.

has it occurred to you that the house ground might be just fine and the outlet you are using is simply a non grounded box?

Have you tested these connections?

What unit are you trying to wire? I know of no motion sensor that relies on a ground wire as a conductor---post a link,--Mike----

Dave632 12-20-2012 09:31 AM

I think I'd go looking for a poor/intermittent connection in the neutral wire. I agree with Oh'Mike, except for GFCI (and maybe AFCI), no device can use the ground connection... that's for safety only.

TTW 12-20-2012 09:40 AM

Oops, I re-read the OP, it's one of those things that replaces the light switch, not a plug in thing. My bad. Completely useless advice removed.


They would rather blame your wiring then their unit.

These are still handy, get one with a button to test your GFCI's


Oh, and these are handy, cheap, and will check for ground connection.


http://i1294.photobucket.com/albums/...tletTester.jpg

bobelectric 12-20-2012 10:04 AM

You aren't confusing neutral with ground,are you?

tylernt 12-20-2012 10:40 AM

Quote:

Originally Posted by bobelectric (Post 1076658)
You aren't confusing neutral with ground,are you?

My thought exactly. Those things often require a neutral, but a neutral often isn't present in switch loop light switches.

silversport 12-20-2012 11:04 AM

I have a leviton that requires a ground but not a neutral.

http://www.leviton.com/OA_HTML/ibcGe...minisite=10251

tylernt 12-20-2012 11:18 AM

Quote:

Originally Posted by silversport (Post 1076695)
I have a leviton that requires a ground but not a neutral.

Interesting. That's a neat engineering solution to the problem, though of course not compatible with GFCI (and I wonder if it might even a trip an AFCI -- depends on the mA the relay coil draws).

Well then, the OP may indeed have a grounding issue. Just because the device is in a metal box and the device is bonded to the box, doesn't mean there is conduit all the way back to the panel or that the conduit has good electrical conductivity.

fowlkesfamily, what year was your house built? Can you take a picture of the metal box with the sensor hanging out of it so we can see inside the box and all the wires?

rjniles 12-20-2012 11:58 AM

Sounds like "technical support" is using this device on the OP:

https://mail.google.com/mail/?ui=2&i....1.4&zw&atsh=1

Tobacco Smoke Enemas (1750s – 1810s)

The tobacco enema was used to infuse tobacco smoke into a patient’s rectum for various medical purposes, primarily the resuscitation of drowning victims. A rectal tube inserted into the anus was connected to a fumigator and bellows that forced the smoke towards the rectum. The warmth of the smoke was thought to promote respiration, but doubts about the credibility of tobacco enemas led to the popular phrase “blow smoke up one’s ass.”

This has been reintroduced in Washington D.C.

Oso954 12-20-2012 01:12 PM

The device operates as described by Technical Support. A high resistance ground might keep it from operating properly. A missing ground would definately effect it. But, it could also be a defective unit.

"except for GFCI (and maybe AFCI), no device can use the ground connection.."
You would be surprised how many devices leak small amounts of current to ground. Most do it for RFI suppression. Many electronic switching devices (wall warts, voltage converters, CFL ballasts, etc) use "a minimal amount of ground leakage".

electures 12-20-2012 01:45 PM

Occupancy sensors impose a small amount of current on the equipment grounding conductor. It is how they work and is the reason for the code change requiring a grounded conductor at every switch location. The current imposed by multiple sensors on the grounding systems of large buildings was causing problems with GFI breakers. Most, if not all, sensors will not function without an equipment grounding conductor.

Check you grounding connections.

AllanJ 12-20-2012 02:04 PM

Quote:

Originally Posted by Oso954 (Post 1076769)
"except for GFCI (and maybe AFCI), no device can use the ground connection.."
You would be surprised how many devices leak small amounts of current to ground. Most do it for RFI suppression. Many electronic switching devices (wall warts, voltage converters, CFL ballasts, etc) use "a minimal amount of ground leakage".

A ground fault circuit interrupter does not (should not) use the equipment grounding conductor. It senses the difference between the hot and neutral currents and trips if the difference is more than a few milliamperes. It does not matter where the difference current went if there was a difference.

It is not unusual for electronic equipment to have one or more capacitors between various parts of the circuitry and the chassis (for RFI suppression). The intent is not to put current on the EGC (back to the panel) but some 60 Hz leakage could occur. In addition, capacitance or inductance induced phantom voltage resulting in a minute current flow on the EGC can occur anywhere in the circuit.

fowlkesfamily 12-21-2012 09:48 AM

Quote:

Originally Posted by electures (Post 1076788)
Occupancy sensors impose a small amount of current on the equipment grounding conductor. It is how they work and is the reason for the code change requiring a grounded conductor at every switch location. The current imposed by multiple sensors on the grounding systems of large buildings was causing problems with GFI breakers. Most, if not all, sensors will not function without an equipment grounding conductor.

Check you grounding connections.

---------------------------------------------------------
Thanks electures (and everyone) for your responses so far. "electures" describes the occupancy sensor exactly like the tech support rep did.

Here is some more detail (and a recommendation I'll try tonight at home). The incoming house wire has 3 wires (red, black, and copper). I connected the red and black wires to the occupancy switch. The copper wire I connected to a ground wire from the occupancy switch, then connected both of these wires to the metal box using a pigtail (and a screw). The technician verified that I had the wires connected properly before telling me that my ground wasn't strong enough.

Friend's recomendation: A work friend recommended the following. Connect the ground wire (from the incoming current) to the ground wire on the outlet. Run a (temperary) copper wire, which connects a copper water pipe to the ground connection (from the switch and the incoming current). If the switch turns off (after the room is vacated), we have identified that the current ground is either not present or too weak for the occupancy switch to work.

BTW, I'll post pictures tomorrow if this doesn't work.

electures 12-21-2012 10:20 AM

Sounds like a plan. Keep us posted. You could also use an extention cord and use the equipment grounding terminal to trouble shoot your problem.

Speedy Petey 12-21-2012 11:17 AM

Quote:

Originally Posted by electures (Post 1076788)
Occupancy sensors impose a small amount of current on the equipment grounding conductor. It is how they work and is the reason for the code change requiring a grounded conductor at every switch location. The current imposed by multiple sensors on the grounding systems of large buildings was causing problems with GFI breakers. Most, if not all, sensors will not function without an equipment grounding conductor.

Check you grounding connections.

I'm sorry, but I don't buy it.
There should be NO current on the equipment ground, period, and I'm not sure what the EG has to do with the grounded conductor (neutral) being required in switch boxes. I can see your point only in that dumb people were using the EG as a neutral in places where a switch loop existed and an OC switch was install that required a neutral. This creates a tiny amount of circuit current on the EG systems which is NOT good.

The equipment ground and the neutral are two different things. I have never seen an OC switch that required an equipment ground to work properly.


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