USB devices lose connection when switching on/off my desk light

Question

I got a very rare incident when I switch my desk light on or off: This is not happening every time, but like 1/10 times. For example, I have my phone connected and switch off my light… Windows instantly plays the sound of a disconnecting/reconnecting USB device and iTunes starts syncing again.

My desk light uses an 11 watt fluorescent “Osram Dulux S” energy saving lamp. When I switch it on, it flashes two times before it’s permanent. It seems, as if this issue only occurs after the lamp was on a longer period, as I cannot reproduce it by switching it on and off multiple times.

The desk light was formerly connected to the same multi outlet socket, but right now it is a few meters away plugged in, but still in the same wall.

Could be, that my problem is a bit off topic, but I thought, that some people here might also know something about electronics ;)

I built this computer myself, but I made a lot time and precision to build it, in order to do everything correctly.

What might be causing this issue?

Answer 1

It's not clear in the question but a comment from the poster mentions the light is plugged directly on the PC, probably on a USB port.

The light is obviously creating a power surge or a voltage drop which affects the other device. That lamp should not be used as it should have been designed not to cause such side effect knowing it would be connected to a sensitive electrical system.

If you really want to use it, you could connect the light to a USB hub that has it's own power source. It should isolate the electrical anomaly from the PC's USB. You could also use a phone charger that has a USB connector. To be safe, make sure the charger is rated at least 1A.