lw395
Well-known member
As stated in post #4
Also when using a LED on a mains circuit you need to select a LED with a high reverse breakdown voltage.
Most LEDs have very low reverse voltage ratings, 5V is quite typical.
It's normal to use a few components around them for a mains indicator.
If you buy a packaged 'Mains LED indicator' it might be capacitively coupled and not work with DC.