LEDs, Dimmers, & Arc Faults

[Cutima]

I've posted here before and received help, so I'll give it a whirl again. I have an issue that has stumped three electricians and possibly the folks at Lutron. I have Ensenior brand LEDs installed in my house with reverse-phase dimmers from Lutron controlling them. When I use the LEDs on low power, AND I have a set of undimmed LEDs on a second circuit, AND I have a heavy load (fridge, coffee maker, air fryer, iron) on a third circuit, the third circuit always trips the arc fault.

Previously, I was experiencing trips on a circuit that had a heavy load on it (air fryer, coffee machine, fridge, etc.) in conjunction with a second circuit where the canless LED lights were attached to a forward phasing dimmer. Lutron suggested I use a reverse-phasing dimmer, which fixed the problem between the two circuits. They were familiar with this problem. However, now when I add that third circuit (basically when I turn an LED light on in a room without the dimmers like the bathroom) the second circuit--the one with the load--automatically trips.

I know the conventional wisdom is to check for shared neutrals, but this is a new build with a new panel and new wiring. Additionally, one of my electricians installed a plug right outside my panel with nothing else but that receptacle on the branch circuit. This circuit will trip if there's a heavy load on it in one of the above situations. I am assuming there's no way that this circuit could possibly have a shared a neutral with any other circuit due to it having its own dedicated wire coming right out of the panel.

Any suggestions here on what the interference might be? I realize that this forum is for certified electricians, but I would love to provide some advice to my electrician. I don't think he'll be coming here on his own.

 

[LarryFine]

Troubleshooting is a process of elimination.

Have your guy try temporarily replacing dimmers with switches, moving breakers to other phase, etc.

I would also contact the LED bulb or light maker. They should have a list of compatible dimmer types.

 

[synchro]

... I have Ensenior brand LEDs installed in my house with reverse-phase dimmers from Lutron controlling them. When I use the LEDs on low power, AND I have a set of undimmed LEDs on a second circuit, AND I have a heavy load (fridge, coffee maker, air fryer, iron) on a third circuit, the third circuit always trips the arc fault.
... However, now when I add that third circuit (basically when I turn an LED light on in a room without the dimmers like the bathroom) the second circuit--the one with the load--automatically trips.

If you turn on the LED light in a room without a dimmer first before turning on the other two circuits (the ones with dimmed LEDs and a heavy load), does the arc fault breaker still trip?
Also, do you have the particular model name and/or part number of the Lutron reverse-phase dimmer being used?

 

[Fred B]

What panel mfg. is installed? Had issue with a Siemens dual function AFGF breaker that was tripping under similar circumstances. Contacted Siemens. The result was related to the dimmer had a noise return that was causing the loaded circuit to trip. It didn't matter which circuit that had the load, the Rep indicated that the noise signature from the one circuit only would cause issue when the other circuit had over a 1-3Amp of draw. (Breaker AF function only looks for the arc signatures when a set min load on the circuit.) Issue he said would not be limited to a dimmer, sometimes a wall wart too would introduce enough noise to be an issue. Can actually hear the noise from the dimmer or wall wart with the receiver of a "fox and hound" tracer.

 

[kwired]

The problem is pushing this AFCI technology and at same time increasing the number of user devices with high speed switching components that won't necessarily play well with the AFCI's, or even many GFCI's don't play so well with them either, and there is no coordination between manufacturers and/or listing requirements they need to follow to assure these things will work together.

 

[Cutima]

If you turn on the LED light in a room without a dimmer first before turning on the other two circuits (the ones with dimmed LEDs and a heavy load), does the arc fault breaker still trip?
Also, do you have the particular model name and/or part number of the Lutron reverse-phase dimmer being used?

No. The LEDs without the dimmers never make the arc fault pop by themselves. It needs to be when there is another circuit with dimmers and a third circuit drawing power. Even odder is that it seems to be only on the 4-inch version of these thin LEDs that are causing the issues. I have 5 rooms where LEDs are used without dimmers and it seems that only the three rooms with the 4-inch version of these LEDs seem to be causing the issue.

The dimmer that I changed to was a Lutron Skylark Contour reverse phase. I had the forward phasing version of this dimmer on all my lights before, but with that version things were popping all over the place. Any time any set of dimmed LEDs woudl go below around 75%, it would cause other arc fault breakers to trip throughout the house when there was a heavy load on them.

 

[Cutima]

What panel mfg. is installed? Had issue with a Siemens dual function AFGF breaker that was tripping under similar circumstances. Contacted Siemens. The result was related to the dimmer had a noise return that was causing the loaded circuit to trip. It didn't matter which circuit that had the load, the Rep indicated that the noise signature from the one circuit only would cause issue when the other circuit had over a 1-3Amp of draw. (Breaker AF function only looks for the arc signatures when a set min load on the circuit.) Issue he said would not be limited to a dimmer, sometimes a wall wart too would introduce enough noise to be an issue. Can actually hear the noise from the dimmer or wall wart with the receiver of a "fox and hound" tracer.

I have a Siemen's panel with a combination of CAFCI breakers and regular breakers. This seems similar to what I have. Small loads do not make the circuit trip, but anything with a moderate draw, even a baby bottle warmer, will trip when the dimmers are working below 75%. What did you do to fix it? The people at Lutron seemed to be familiar with the issue and offered the reverse-phase dimmer as a solution. It has helped, but not totally fixed the problem.

 

[synchro]

If you turn on the LED light in a room without a dimmer first before turning on the other two circuits (the ones with dimmed LEDs and a heavy load), does the arc fault breaker still trip?

No. The LEDs without the dimmers never make the arc fault pop by themselves. It needs to be when there is another circuit with dimmers and a third circuit drawing power.

To clarify my question, I was asking whether it mattered what order you turned on the three circuits. And specifically, if you first turned on the the LEDs without a dimmer, and then turned on the other two circuits, would that make a difference. Other turn on sequences could be tried as well.
Perhaps the turn on sequence doesn't matter, but if it did, it might offer additional insights.

 

[Cutima]

To clarify my question, I was asking whether it mattered what order you turned on the three circuits. And specifically, if you first turned on the the LEDs without a dimmer, and then turned on the other two circuits, would that make a difference. Other turn on sequences could be tried as well.
Perhaps the turn on sequence doesn't matter, but if it did, it might offer additional insights.

Gotcha. I have checked the order a bit. The effect can always be reproduced when I turn the LEDs first and then add the load on the third circuit. As soon as the appliance starts up, it will automatically trip. However, If I have the appliance on and then turn on the LEDs, it will not always trip. Sometimes, as soon as I turn the light on, you'll hear the click, but other times I'll get a good 20-30 minutes of usage before anything trips

 

[ptonsparky]

Sounds like you need to get rid of the dimmers entirely or have you tried that already?

 

[Cutima]

Sounds like you need to get rid of the dimmers entirely or have you tried that already?

I could... there's no trips if the dimmers are at 100% all the time. Which I would assume also points to the idea that there's not shared neutrals or nails gone awry in wiring. But, I'd rather not have to do that. Whole house would look like a supermarket.

 

[synchro]

Perhaps you could get your electrician to temporarily add a small incandescent light on the dimmer circuit. Sometimes dimmer circuits are less stable with an LED light when dimmed down because these lights are drawing a small amount of current through the dimmer, especially near the zero crossings of the line voltage. Just speculating, but perhaps such an instability could be interpreted as having the current signature of an arc by the breaker and then tripping it. And maybe some of the switching frequency content of the non-dimmed LED lights is being conducted to the bussbars of the breaker panel and over to the dimmer, and then pushing it over the edge into instability. It wouldn't necessarily cause observable flickering if the instability was at higher frequencies.

Also, the dimmer you have requires a connection to the circuit's neutral conductor. I'm not sure if the dimmer would be functional without this connection, but even if it's functional a neutral might be needed to reliably detect waveform zero crossings. And so it could be worthwhile to verify that the neutral is connected to the dimmer.

 

[ramsy]

Additionally, one of my electricians installed a plug right outside my panel with nothing else but that receptacle on the branch circuit.

Load feed a Lutron AFTR2 from that receptacle to protect downstream loads, alowing replacement of Siemens AFCI w/ regular breaker.

(Siemens) Rep indicated that the noise signature from the one circuit only would cause issue

Lutron seemed to be familiar with the issue

Lutron AFTR2 also has no ground fault feature, like your full-size Siemens AFCI does.

 

[Cutima]

Perhaps you could get your electrician to temporarily add a small incandescent light on the dimmer circuit. Sometimes dimmer circuits are less stable with an LED light when dimmed down because these lights are drawing a small amount of current through the dimmer, especially near the zero crossings of the line voltage. Just speculating, but perhaps such an instability could be interpreted as having the current signature of an arc by the breaker and then tripping it. And maybe some of the switching frequency content of the non-dimmed LED lights is being conducted to the bussbars of the breaker panel and over to the dimmer, and then pushing it over the edge into instability. It wouldn't necessarily cause observable flickering if the instability was at higher frequencies.

Also, the dimmer you have requires a connection to the circuit's neutral conductor. I'm not sure if the dimmer would be functional without this connection, but even if it's functional a neutral might be needed to reliably detect waveform zero crossings. And so it could be worthwhile to verify that the neutral is connected to the dimmer.

This might indicate a little bit why it happens more with teh 4 inch lower wattage LEDs. In regards to using the neutral wire, I definitely am using them in the reverse-phase dimmer, as that is needed. It looks like the new LEDs given to me by Ensenior, might actually be playing nice. No trips in 3 days. I was told that they are "optimizing the power signature" by customer service. Whatever that means, they might have fixed the driver a bit to deal with this. If not, I'll be back looking for someone to perhaps provide some assistance on a ferrite choker or something that would get rid of that noise on the panel.

 

[kwired]

Perhaps you could get your electrician to temporarily add a small incandescent light on the dimmer circuit. Sometimes dimmer circuits are less stable with an LED light when dimmed down because these lights are drawing a small amount of current through the dimmer, especially near the zero crossings of the line voltage. Just speculating, but perhaps such an instability could be interpreted as having the current signature of an arc by the breaker and then tripping it. And maybe some of the switching frequency content of the non-dimmed LED lights is being conducted to the bussbars of the breaker panel and over to the dimmer, and then pushing it over the edge into instability. It wouldn't necessarily cause observable flickering if the instability was at higher frequencies.

Also, the dimmer you have requires a connection to the circuit's neutral conductor. I'm not sure if the dimmer would be functional without this connection, but even if it's functional a neutral might be needed to reliably detect waveform zero crossings. And so it could be worthwhile to verify that the neutral is connected to the dimmer.

How about minimum load capacitor?

 

[mtnelect]

Troubleshooting is a process of elimination.

Have your guy try temporarily replacing dimmers with switches, moving breakers to other phase, etc.

I would also contact the LED bulb or light maker. They should have a list of compatible dimmer types.

I call it the "Scientific Method" ... I use it all the time.

 

[ptonsparky]

I call it the "Scientific Method" ... I use it all the time.

Shotgun diagnosis. Shoot parts at it until something hits the target.

 

[Cutima]

How about minimum load capacitor?

What's your theory behind this? I'll bring it up to the Lutron guys since they make one. Are you thinking that that the low wattage needed for the LEDs produces a certain signature or noise that interferes with the arc faults?

 

[LarryFine]

What's your theory behind this? I'll bring it up to the Lutron guys since they make one. Are you thinking that that the low wattage needed for the LEDs produces a certain signature or noise that interferes with the arc faults?

I'd say that an incandescent bulb tends to make the LEDs track the dimmer output better.

I put one in a chandelier, and the 11 LEDs dimmed perfectly; without it, bright or off only.

 

[kwired]

What's your theory behind this? I'll bring it up to the Lutron guys since they make one. Are you thinking that that the low wattage needed for the LEDs produces a certain signature or noise that interferes with the arc faults?

Well both the dimmer and the LED can produce high frequency noise with the high speed partial wave switching going on. I don't know if a capacitor would help or not, it will add more load with less loss since it is not a resistor though there is still some resistance loss in a capacitor as well. That added load is linear load just like a resistor is. AFAIK they were intended to smooth out the dimmer output to limit variances in the LED output more so than to address any input side of the dimmer issues. Adding a resistance load instead of the capacitor would do the same but would have more energy losses than a capacitor.