View Full Version : Home Electrical Phenomenon

10-13-2008, 09:04 AM
I've got one of those gremlins at the house that continues to baffle me. I haven't taken the time to pull open/apart the wiring because it's not that big a deal for us, but it always makes me laugh when it happens.

Here's the deal. I've got an overhanging back porch that was added on to the house by the PO. They added a new ceiling fan and light, tapping into the existing back porch light that came with the house originally. The back porch light is controlled by a switch, which is supposed to turn on both the back porch light, and the new fan/light combo.

In the summer months when it is hot out, the switch turns on the back porch light, but the ceiling fan/light combo never comes on. I can pull the manual cords all day long, and nothing happens.

Recently, as the weather turned colder, I now turn on that same switch, and sure enough the fan starts spinning on high, and the ceiling fan light comes on. The cords on the unit work to turn off/on the fan and light. This same phenomenon also happened last winter - albeit inconsistently.

So I'm assuming I have a short in the fan wiring somewhere, probably in the junction box where they tapped into the existing house wiring for power. But why does the fan work only when its cold outside? What physics are in play here to make the wires short out in hot weather, and functional in cold weather? :confused:

10-13-2008, 12:26 PM
Rather than a short, you probably have an intermittent open. I have seen terrifying things when opening electrical boxes where POs have ventured without qualification. With apologies to Mr. Biden for stealing his earlier comment, electrical work is not an entry level position.

You probably have a nut loose in your electrical box. From having had a nut loose in your electrical box. Kill the breaker, open the box, take the lineman pliers and tighten the twists. Don't be surprised to find they used a ground for the neutral or have white to black tied together for some reason that only made sense to the PO.

10-13-2008, 02:29 PM
You may find that the PO tapped into the system without adding a box - I've seen Romex wire just twisted together in the walls. It's possible your house shifts and changes shape a bit during colder weather and pulls on a wire, establishing contact.

You need to investigate this sooner, rather than later, from a safety standpoint.

10-13-2008, 02:41 PM
Do you have aluminum wires?

10-13-2008, 03:48 PM
All of the wiring I've seen thus far in the house is copper and looks good, although its anyone's guess as to what was used to extend the circuit out to this fan. I'm hoping it'll be a simple and obvious fix once I open up the box and clean up the existing connections.
But it's the weather related on/off that had me curious.

10-13-2008, 04:28 PM
Highly doubtful they could have used aluminum to extend your wiring, it would most likely only be the main house wires... I think it was outlawed around 1975? But I'm guessing there's a loose connection, and it's in the box behind the light that works all the time, where it connects to the feed to the ceiling fan. My hunch is that one wire is coiled around another wire, with a tiny gap inbetween- like a corkscrew around a stick? When it gets cold, the outer coil shrinks, and the connection is made... that could be potentially worse with AL since it's got a higher coefficient of thermal heat & expansion, which is why it got outlawed. it's a great conductor, though!

10-14-2008, 08:01 AM
Not as good as copper by any means though.

My bet is that the PO wrapped the wires together, probably used an extension cord, and 'insulated' it with electrical tape. :eek: