Christmas Lights! And Circuit breakers!

proXimity

So my dad always likes to put up a lot of Christmas lights, and this year, instead of running off pre-existing circuits that may trip when somebody uses a hairdryer, he decided to have a dedicated circuit installed for the lights, with it's own breaker.

Here's the curious part. When the lights are first turned on each night (with a remote thingie), they'll stay lit for maybe 10-30 seconds, then the breaker will trip. He'll then go down and reset the breaker, and then turn them on again. This time, they'll stay lit for the rest of the night, no problem.

The only explanation I can think of for this bizarre behavior is that the incandescent lights (there's not LED lights) draw more power when they're cold, and when they are heating up for the first time, they draw just barely over the breaker's limit, and trip it shortly after turning on, then when the breaker is reset, they're warm enough to not draw as much power and run fine. Is this what's going on?

Robman

I would suggest to your father that he install a second dedicated breaker and line for these exterior lights - you're probably running pretty close to the maximum supported wattage for the line and breaker, and that's a great way to burn down your house.

Improvolone

I would also suggest upgrading to LEDs because, good god

proXimity

Robman wrote: »

I would suggest to your father that he install a second dedicated breaker and line for these exterior lights - you're probably running pretty close to the maximum supported wattage for the line and breaker, and that's a great way to burn down your house.

That's what this is, a dedicated line just for christmas lights.

McViking

You're pretty much on the money, I think. According to the Wikipedia article, "The cold resistance of tungsten-filament lamps is about 1/15 the hot-filament resistance when the lamp is operating." Which means that there's an initial power surge while the filament warms up. For a 100W bulb at room temperature, the initial power surge is momentary, but I would imagine that for low-wattage Christmas lights outdoors in sub-zero temperatures, it may actually take a few seconds before they're sufficiently warm to reach full resistance.

Disclaimer: I am definitely not an electrical engineer nor an electrician.

TOGSolid

proXimity wrote: »

So my dad always likes to put up a lot of Christmas lights, and this year, instead of running off pre-existing circuits that may trip when somebody uses a hairdryer, he decided to have a dedicated circuit installed for the lights, with it's own breaker.

Here's the curious part. When the lights are first turned on each night (with a remote thingie), they'll stay lit for maybe 10-30 seconds, then the breaker will trip. He'll then go down and reset the breaker, and then turn them on again. This time, they'll stay lit for the rest of the night, no problem.

The only explanation I can think of for this bizarre behavior is that the incandescent lights (there's not LED lights) draw more power when they're cold, and when they are heating up for the first time, they draw just barely over the breaker's limit, and trip it shortly after turning on, then when the breaker is reset, they're warm enough to not draw as much power and run fine. Is this what's going on?

That's pretty much spot on, but it also means that you're still running way too god damn many lights off that breaker. You don't want those breakers to be tripping on a regular basis like that.

Note: I'm not a licensed electrical engineer or electrician, but I am studying it for my 3rd engineer's license.