Flickering Light

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Sparky1981

Sparky1981

PE
Location
Denver, CO
Occupation
Electrical/Lighting Engineer
I have a rental property with an issue. I am headed to the property next week to dig in more but wanted to pick your brilliant brains here first. Here is the issue. There are three rooms at play here. The kitchen, connected to a dimmer. The dining room, which is a fan/light connected to a switch, opposite side of the wall from the kitchen dimmer. And a half bath, switched, room directly across the hall from the kitchen. Small space and most likely these are all on the same circuit.

The issue is when the switch to the dining room fan/light is on, just this, the light is fine. When the kitchen light dimmer is at 75%, the dining room lights on the fan begin to flicker. I am talking a hard flicker, more of a strobe. But this stops when the half bath light is turned on.

My question to you is what are possible issues you see? I believe the lamps in the fan/light were changed by another tenant to LED or CFL. I am going to change these to incandescent. Still a bit bizzare they strobe since they are switched and the dimmer is for the kitchen but perhaps there are some harmonics getting to the fan lights when the kitchen is dimmed making the LED in the fan freak out. Any thoughts would be most helpful.
 
My experience with this is to use a different brand dimmer or even possibly change the brand of bulbs in the fan (especially if they are LED) some of these drivers for LED get real fickle when noise is induced on the line coming from various apparatus such as some dimmers, load cut-out units, etc
 
Sparky1981 said:
I have a rental property with an issue. I am headed to the property next week to dig in more but wanted to pick your brilliant brains here first. Here is the issue. There are three rooms at play here. The kitchen, connected to a dimmer. The dining room, which is a fan/light connected to a switch, opposite side of the wall from the kitchen dimmer. And a half bath, switched, room directly across the hall from the kitchen. Small space and most likely these are all on the same circuit.

The issue is when the switch to the dining room fan/light is on, just this, the light is fine. When the kitchen light dimmer is at 75%, the dining room lights on the fan begin to flicker. I am talking a hard flicker, more of a strobe. But this stops when the half bath light is turned on.

My question to you is what are possible issues you see? I believe the lamps in the fan/light were changed by another tenant to LED or CFL. I am going to change these to incandescent. Still a bit bizzare they strobe since they are switched and the dimmer is for the kitchen but perhaps there are some harmonics getting to the fan lights when the kitchen is dimmed making the LED in the fan freak out. Any thoughts would be most helpful.
Click to expand...

I agree with the others on this. Before you start tearing wiring and splices apart the first thing I would do is replace the dimmer with a std. switch and see what happens. If you still have flickering change at least one of the bulbs to an incandescent. If you still have flickering I would delve further into possible loose connections.
 
That’s the part that is so weird. The dimmer is not connected to the lights flickering. The dimmer is connected to the kitchen lights, which are incandescent, and don’t flicker.
 
The lights are dimming on the ceiling fan?
how new is it?
New ceiling fans with watt limiters don’t really like anything but incandescent bulbs. They strobe bad.
the watt limiter switch is chattering causing the strobe I believe. I take fans down, remove the watt limiters and put them back up quite often. Problem solved.

could be something else though... change the three bulbs to incandescent first, see if problem goes away. If it does, it’s a watt limiter in the fan.
 
Sparky1981 said:
That’s the part that is so weird. The dimmer is not connected to the lights flickering. The dimmer is connected to the kitchen lights, which are incandescent, and don’t flicker.
Click to expand...

I’m hearing you, I am on board with it being possibly a watt limiter control in the fan along with led bulbs reacting erroneous to noise put on line by the dimmer in the kitchen. I may add that this could even further be exacerbated if this rental is still using K&T wiring and the polarity is backwards.
 
Townhome was built in the 80s so no K&T wiring. I will be there next week. I am hoping the lamps in the fan are LED and changing them will fix this. Otherwise I am totally lost and will probably need to hire somebody to start taking lights and switches out to check the wiring.
 
If the bulbs in the fan are non-dimmable LEDs, then another suggestion is to replace them with dimmable ones (even though they are not the ones being dimmed). Non-dimmable bulbs have cheaper switching supplies in them that can't tolerate the ragged waveforms and harmonics of a dimmer output. But they would also be more susceptible to any noise put on the branch circuit by the dimmer in the other room.
 
If I lived there for sure. But I just want it to work and do it cheap. If my tenant wants to change to LEDs from there that’s on them. I just want something that works.

I am pretty sure an old tenant, not understanding lighting most likely put in a cheap non dimmable LED that is being sensitive to the dimmer in the kitchen.

Just as a thought exercise why does turning on the bathroom make the flickering stop? I have my theory just curious what you all think.
 
Sparky1981 said:
If I lived there for sure. But I just want it to work and do it cheap. If my tenant wants to change to LEDs from there that’s on them. I just want something that works.

I am pretty sure an old tenant, not understanding lighting most likely put in a cheap non dimmable LED that is being sensitive to the dimmer in the kitchen.

Just as a thought exercise why does turning on the bathroom make the flickering stop? I have my theory just curious what you all think.
Click to expand...

Turning on the bathroom light now again changes the characteristics of the entire circuit attenuating the condition which is questionable to the bulbs flickering in question. Maybe for example, the bath light bulb may be led or cfl and have a capacitor within it may quench the effects that the kitchen dimmer may be emanating, or maybe even circuit wire length and impedance, reactance, capacitance.
Fun times indeed!
 
190929-1344 EDT

Look at the voltage waveform with a scope. Also test the LED on your bench with various noise sources, and see if you perturb the LED.

.
 
It was the lamp. The LEDs put in the fan were made in China with no manufacturer. The only marking I saw was the lamp base and CCT. I put it on a dimming circuit, thing went nuts. Was a junk lamp.

This is why I love electrical! A dimmer for one room was able to dirty the power in another room causing the cheap lamp to strobe.

Mods can close this if they want.
 
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