I am miffed at this one.

The home is recently purchased, built in 1973, and is nothing fancy. I can't imagine that I would have some newfangled system installed at the time (or retrofitted). I was taking a break from troubleshooting my AC/heatpump problem, when I.....

I was installing a recessed can light over my shower. So I go to cut the hole from the attic (I am getting smarter so I mark it below, go into the attic and make sure I'm not going to hit a studs) . I think to myself as I am cutting, "geeze this is the hardest sheetrock to cut." Nothing is in the way though. The circle falls down and there is a tiny white wire across the hole. Dang, i think I cut the door bell. So I go down and look up and I have actually cut through 4 tiny wires (were talking a 6" diameter circle here) that are running in parallel grid. The wires were purposefully put there, ARE EMBEDED in plaster (downside, not above) that is attached to the sheetrock, either at the factory or afterwards (they are so perfect that it looks like something that came from the factory).

The are white with a blue writing that says E-33178 90C UL. I swear this looks like the type of floor heater grid. I have never heard of a heated ceiling. I called my uncle who has been building houses for 40 years and he had never heard of such a thing.

Can anybody give me any insight into this. Can I proceed and forget about it? Is this something for structural support or something that was installed and not hooked up. I can find no evidence of any type of thermostat and I have cut into the side drywall without ever seeing these wires.

Anybody???

 

I gave a response on your other thread as well.

This sounds just like what you thought it was, an electric heating grid. My dad has this in his house. Do you have t-stats in each room? This was usually controllable in the individual room and would have a t-stat for that.

If you don;t use it now, you aren't hurting anything other than you should make sure it is actually disconnected. It is line voltage and if it became energized, you may very well end up with one on those wires with voltage oozing out of it and into whomever is the unlucky person to touch it, or the light you are putting in, if it is not grounded by some chance.

 

This type of ceiling heat would have a dedicated circuit breaker. Have you checked the panel?

 

Somebody has not marked all the slots. It does not appear as if there is a dedicated circuit breaker for this. I have two 240 circuits that I can not identify. I think one is for an old baseboard heater, the other I am not sure.

I did test all the cut wires in the ceiling and none of the six open ones had any voltage going through it (one had 0.5 volts, which I think was from the fan that was spinning right next to it. When I turned the fan off, no more voltage). I would expect to see some sort of control for the thing, if it was hooked up. My guess is that it may have been an option on the house, but was not exercised or some supply house sent the wrong stuff and the builders just used it.

You got me. I seems like if ceiling heat was in that bathroom there would be some switches or tstats.

 

The wire you encountered is part of the radiant ceiling heat system. I found exactly the same wiring during the renovation of my condo. Technically, it is not installed as a grid. Normally it is installed by stapling it to the ceiling sheetrock after the sheetrock has been installed and then covered with about 1/8 inch of plaster (in my case one layer of coarse plaster covered by a smooth coat). The wire wraps back and forth across the ceiling and is routed around any ceiling fixtures. In my case it is then connected to a simple bimetal thermostat and the 210V service.

 

Welcome to the forums.

I see you dredged up a thread from the vaults.
We try to let sleeping threads lie.

Also...your electric service is 240 volts.