The items involved are:
A duplex remotely controlled by and on-off/dimmer switch.
A string of 200 LED Christmas lights plugged into one of the duplex sockets.
As string of 60 LED Christmas lights plus a string of 100 incandescent
miniature Christmas light plugged into the other duplex socket via an
extension cord with an in-line switch.
Now, here's the strange event:.
The dimmer was set to about 90 volts (by accident, forgot to reset when we
plugged in the Christmas lights). When the switch on the extension cord is
turned off, the remaining set of 200 LED lights dims significantly. Why?
When the duplex outlet operates at full voltage this doesn't happen.
Don't know exactly, but I'd figure it has to do with power factor
Wait a minute ...
Are you saying that the remote is a dimmer? Does it do this by
controlling dimmer circuitry which is actually in the receptacle?
Otherwise it sounds like a neat trick to me. But assuming the actual
dimmer circuitry is in the receptacle, the fact that a remote is
involved is not relevant.
Most dimmers assume the power factor doesn't matter, which is true for
incandescent lighting. But the transformer/rectifier which feeds the
LEDs has a strong angle to its power factor. So the incandescent
lights absorbed part of the power factor mismatch. When you turned off
the incandescents, the power factor mismatch to the transformer became
much more significant. Yeah, I'm waving my arms around and haven't
figured it out exactly.
When the dimmer is at full voltage, it is essentially shorted and does
not alter the power factor.
The duplex outlet is about seven feet above the floor and is typically used
to power lights above or on the fireplace mantle. The hardwired dimmer is
located remotely (a few feet away) at normal switchplate height. During the
holidays a couple of Christmas light strings replace the usual mantle
The LEDs draw very little power, apparently not enough for the dimmer
to behave "properly". A clue to this is that there are low load dimmers
I wouldn't worry about it.
I think that may be the answer. It seems to make sense (to me, at least)
that having low load, diode limited light strings in series with a device
that truncates the wave form could some type of unusual triggering in the
dimmer. It would be interesting to introduce an incandescent light into the
arrangement to see what effect the increased load would have. Lest anyone
continue to think I'm attempting to dim LED's, that proposal would be just
for investigation purposes.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.