Power surges from rapid on/off?

March 24, 2012 11:58 AM

Does flipping a switch on and off rapidly damage electrical equipment?

My grandpa did this in succession because he keeps on forgetting that one of the light switches in my room controls one of the power outlets that I use to charge my phone and laptop. Instead of just remembering that the light switch controls the power and not only the lamp that is connected to one of the sockets in the outlet, he decides to flip the switch on and off over and over like 5-6 times in quick succession while my phone is charging.

Will this damage electronic equipment? If I have a surge suppressor power strip (which I have plugged in, with all my stuff connected to it), will it prevent anything like this from occurring?

posted by antgly to technology (12 answers total)

It's conceivable, but it isn't a very high risk. Not that it's a good thing, but it isn't the catastrophe you're imagining.

Put a piece of duct tape on the switch so that it can't be flipped easily.
posted by Chocolate Pickle at 12:29 PM on March 24, 2012 [2 favorites]

In short, no, not a bit.

When you flip a switch, there's nothing in the power system of the house or the grid that will cause any sort of spiking. Transformers (like wall warts) are designed to be switched on and off, and would certainly be designed to accomodate any sort of internal voltage spikes. There is a tiny, tiny chance that the electronics heating and cooling slightly could reduce their lifespan, but the electronics themselves would likely corrode first. At the very worst, it could confuse the software in the phone that displays whether it's charging, but that'd be a really weird bug, and not at all likely. And like, maybe he's wearing out the wall switch a bit?

In fact, the only detrimental thing he's doing is annoying you. :)
posted by TheNewWazoo at 12:33 PM on March 24, 2012 [1 favorite]

Since it's just the chargers you're cycling, not the devices, no, not really. No more than plugging it in does, anyway. If it were a desktop, it might be different. And the surge protector won't do anything, since it's not causing power surges. To ensure continuous power flow, you'd need a UPS, which is overkill for the remote possibility of damage.
posted by supercres at 12:37 PM on March 24, 2012

If it would set your mind at ease, maybe you could plug your stuff in a different outlet.
posted by box at 1:09 PM on March 24, 2012 [2 favorites]

My brother used to come into my room when I was a teenager all the time. He'd flip the light switch on and off and on and off and on and off and on and off. After some months of doing this, my touch lamp (which was plugged into the outlet that was connected to the light switch) burnt out.
posted by aniola at 1:09 PM on March 24, 2012

In your case, no. It's power cycling the chargers which are made to cope well with that kind of thing. The power to your devices is evened out by the battery so your actual device doesn't even see it. (Other than changing an icon that says "charging" or "not".)

There are cases where rapid power cycling can cause problems. For example with incandescent light bulbs but that's because they're heating and cooling (expanding and shrinking) dramatically which will shorten their lives. But outside of incandescent bulbs, there's not a lot of danger.
posted by Ookseer at 1:11 PM on March 24, 2012

You want some cheap plastic switch guards.
posted by thejoshu at 1:21 PM on March 24, 2012

Lots of devices experience the most stress at the time they're switched on. Doing this to a tube TV or a large electric motor or a server rack would probably shorten their lifespans. Doing this to a couple of battery chargers probably causes no harm at all.
posted by hattifattener at 1:35 PM on March 24, 2012

Anecdote from years ago: A physician at a medical school where I worked in the mid 1980s once became so frustrated with his IBM PC that he did exactly that, and the power supply blew.
posted by davcoo at 4:36 PM on March 24, 2012

PCs of that era used analog power supplies. Modern computers (and charging bricks for phones, etc.) use switching supplies. It's an entirely different approach, and they don't act the same under stress.
posted by Chocolate Pickle at 5:54 PM on March 24, 2012

PCs of that era used analog linear power supplies. Modern computers (and charging bricks for phones, etc.) use switching supplies.

No, all Apple and IBM PCs used switch mode power supplies starting from the original IBM PC and Apple II. All power supplies, switching or linear, are analog designs.
posted by JackFlash at 6:51 PM on March 24, 2012 [1 favorite]

When you flip a switch, there's nothing in the power system of the house or the grid that will cause any sort of spiking.

TheNewWazoo, you're apparently unaware of line reactance... The spark you can see in the dark if you flip (many) power switches with their covers off proves there is spiking.

supercres has it: Since it's just the chargers you're cycling, not the devices, no, not really. No more than plugging it in does, anyway. If it were a desktop, it might be different. And the surge protector won't do anything, since it's not causing power surges. To ensure continuous power flow, you'd need a UPS, which is overkill for the remote possibility of damage.

Some electrical devices could suffer, but not a computer (not even a desktop, as their internal power supplies buffer the spikes fairly well).

An example of a possible problem from those on-off spikes (from aniola):
My brother used to come into my room when I was a teenager all the time. He'd flip the light switch on and off and on and off and on and off and on and off. After some months of doing this, my touch lamp (which was plugged into the outlet that was connected to the light switch) burnt out.

Those have fairly sensitive detection circuits in them; thus, susceptible to spikes.
posted by IAmBroom at 1:54 PM on March 26, 2012