On Sun, 8 Dec 2019 12:44:17 -0800 (PST), Thomas
wrote:

Just put in a new led ceiling light in bedroom, 3 wires, the third capped and taped.
The leds glow with the wall switched off. How is that posible? Installed with breaker off, hand twisted nuts and tape. Does the light retain x for a time?

It may glow for a minute or so as the capacitors in the power supply
discharge but it should go out. If this is not just a regular snap
switch but some kind of electronic switching, there can be enough
leakage in the triac to keep it from going off or just make it flash.