Hi,
From the Doorbell Switch picture, could SIFU around point out what color of wire for L & COM? 🙏


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Live wire will have power. Use a test pen.

to be really sure need to test on the spot, if unsure just get an electrician to do it, you don't want to get toasted just to save berpuluh ringgits.

Ok! So, use the test pen to test, if that's Live (light's on), then connect to COM?

Btw, L stand for Loop?

L is Live.
COM is Common or usually Neutral.

Door bell should have 4 wires. 2 for power and 2 for switch.

Switch wires u can test with a multimeter. Test pen will not produce anything but u can tie both wires together and use diode mode to test for short.

U just need to be careful with Live and Neutral wires only. Usually if followed the standard, neutral is black or blue and live can be yellow or red. Then again, some electricians too lazy and will use any wires. Just be careful.