Christmas outdoor LEDs problem

ok, so way off topic.

i purchased a seasonal (not to be used outdoors for > 90 days) outdoor-rated (weatherproof, not waterproof) digital timer from costco last year.

plugged in numerous strands of my old-fashioned outdoor christmas lights, no problem.

this year i replaced the "old-fashioned" lights with strands of leds.

used the same timer.

the lights came on as advertised. they were scheduled to go off at 2200. to my great surprise and amazement, when i got up at 0500 the leds were, for lack of a better description, glowing. they were on, but not full strength.

the leds manufacturer says that's interesting, never heard that one before.

the timer folks say that they'll replace the timer but haven't an explanation.

my electrician says to just replace the unit. an electrical switch is either on or off.

i then plugged a strand of old-fashioneds into the timer and ran through a cycle overnight. they were not glowing in the am.

i purchased a new manual timer. plugged in the strands of leds. came on at the designated time, apparently went off at the designated time, and were not "glowing" at 0500.

the "glowing" was eerie, but not sure how safe it was.

any thoughts?

Normally an electrical switch is "ON or OFF" and the electrician is correct. Now walk over to the wall and ever so slowly (really slow) turn ON or OFF a light switch and watch the bulb. See it dim and then flicker before going off? That is the switch just starting to break contact. Electricity is arcing across the contacts providing a poor circuit contact to ground. That is why you hear the crackling noise behind the switch.
Now then, quit playing with the light switch! Didn't your parents teach you that was bad on the bulb!!!

Well it probably isn't a safety problem but it is a nice example of why LEDs are so much more efficient than standard incandescent lights.

The digital timer isn't completely breaking the circuit like an older mechanical timer would (solid state switching vs. relays). Most inexpensive digital timers bleed through a little current when "off". This isn't enough to light your older lights since they require more current to light - typically about 0.24 Amps for 100 modern "efficient" mini-lights. As a comparison LEDs run about 0.067 Amps for the same number of bulbs.

So if your timer is leaking something like 0.02 amp (1.2 watts) when "off" the LEDS will probably glow and while the older lights are "live" they won't light up. This can easily be checked with a digital volt meter but remember to play safe with electricity - at a minimum 120VAC smarts when you accidently join the circuit and the results can be much worse.

Personally I think the glowing would be cool.

- Eric

Electronic switches (like those in your electronic timer) are SCR's or triacs. Like any semiconductor they to have some off leakage. Just buy one of those mechanical timers that have the motor that turns the dial.

eric ~ thank you for the explanation. i was concerned about the safety aspect.

and yes, the glowing is very cool!