I recently replaced the some floodlamps with LED lights. The problem is some of the LEDs are blinking or flashing even though the switch is off. Some do not blink at all. It happens all the time. Is it harmful or can it cause a house fire?
It appears to be a bad/weak/intermittent switch. I highly advise you to replace it!
SDsolar commented:In the comments to the answer is a link to a similar article where it is said that the ground wire was not at the same potential as the neutral, and that ungrounding it solved their problem. Not that it would seem an ideal solution, of course. And you might be right about an intermittent switch. But I'd suggest you flesh out your answer with examples to support your answer. – SDsolar yesterday
When you have a different potential between the neutral and load and ground and load, it would mean a measurable voltage between ground and neutral. That would mean that the potential in the neutral is being "bled off", resulting in a lower voltage being applied to the load.This will cause "non dimmable" LED lights to flash
It would seem in the above case, that "un-grounding stopped the voltage on the neutral line to stop being "bled off", leaving a greater potential (voltage) between the neutral and load...enough to stop the flashing. I would be curious where they measured the potential difference. If the switch were still attached, and they measured at the screw terminals, I would suspect the switch is at fault. I hope I am more clear now, SDsolar.