Power is out, generator is on, lights on z-wave dimmers flickering?

So bad storm in NJ today, close to 2’ of snow. Needless to say, power is out, by my general (12kw) kicked on no problems. This is the first time I had to use it since upgrading all my switches to Leviton switches (rf+ series) and the seem to be acting erratically. All dimmers flickered, no matter the brightness level and regular switches seem to turn on and off sporadically. Can anyone even remotely take a guess on what’s going on and is there a way to fix it or can I just not use my lights when I’m on backup power.

There are a few reasons for this. The most likely explanation is that the generator is a MSW (modified sine wave, aka “rounded square wave”) and/or may not be outputting a stable 60hz frequency. I would suggest measuring the AC voltage to see if that’s stable too.

It’s likely just a typical, normal dirty MSW generator which don’t play well with sensitive electronics.


Thanks for the feedback Steve. The generator is throwing a battery error as well. I have a maintenance contract on it, so they will be out tomorrow. I’ll have them check the voltage and frequency while they are here. Is there anything I can do to the correct the issue? Like inline power conditioner?

I know it’s been awhile, but quick update. The battery error was just a general maintenance thing. Apparently, the company I use for generator service uses it as a service reminder notification.

Anyways, I lost power today for a few minutes and when it came back up my lights were all flickering again. This was on regular power, not generator. The dimmers were literally strobing. I turned the breaker on and off for the hell of it and it instantly fixed the problem. I only thought of it as the clock on my stove sometimes gets out of whack with power outages. It actually runs faster than it should and I have to reset the breaker to fix it.

Still have no idea what is causing the issue with the lights, I have to see if resetting the breaker during an actual outage would fix the problem.

I would call your power company or get an electrician. We had similar events in an old house years ago. Tree roots had damaged the neutral line in from utility. That problem wasn’t fully revealed until the electrician added proper grounding (rods) to the house as a first step to resolve odd flickering and other problems we were having.

In fact right after the grounding rods were installed and circuits powered on, the neighborhood Comcast box that was in my front yard and grounded to my house, went up in smoke and flames. It was a pretty exciting day. Power utility dug up my driveway and fixed everything at no cost to me, but didn’t reimburse for the kitchen oven control board which was also fried.

Once all fixed, the utility guy said “always call the utility first when you notice problems with your lights or power”. Could have avoided paying the electrician for grounding.

Pretty sure it has nothing to do with my utility power and everything to do with the generator screwing with the z-wave dimmers. This is a 10kw natural gas fed generac. I figured the power isn’t as clean, but had the technician test everything when he was doing general maintenance on the unit. Clean 60hz, no not sure what is causing the issue. Like I said, as soon as I reset the breakers it was working fine. Just have to test it when I’m on generator power. Maybe it has something to do with the transfer switch.

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One cheap test you could run is to rent or borrow a “pure sinewave” generator. If you know someone with an RV, they probably have one. Also, are the bulbs LED or incandescent? It they are LED, try an incandescent. LED’s can be picky on wave shape and level.

According to my generac manual…

“Superior harmonics and sine wave form produce less than 5% Total Harmonic Distortion for utility quality power. This allows confident operation of sensitive electronic equipment and micro-chip based appliances, such as variable speed HVAC.”

So, it shouldn’t be causing any issues. The bulbs are all LED on leviton z-wave dimmers and switches.

I encountered the same thing - power went out, generac went on, and lights were flicking even after utilities came back. After turning off and on the main breaker, the light returned to normal.

The difference is that: my dimmers are Wemo Dimmer Swich, which control 9 LEDs and CFLs - they were all flickering. On the other hand, others are working fine, including Cree Connected Bulb, Hue Bulbs, and other non-dimming z-wave and Zigbee outlets.

The problem is probably with dimmers themselves. Though why it requires a main breaker ‘reset’ is very troubling.

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I know this is years old so for you may be irrelevant. But I fixed mine and maybe someone else can benefit from my work. That said, I read this trying to solve my similar issue with my 9500 Watt portable Generator and my Wemo dimmer controlling LED bulbs. Nothing in this thread helped my situation. Further research indicated that these GFI protected generators create a neutral ground loop when connected with a house transfer switch as the neutral is connected back through to the house service panel which is also grounded. That is exactly what my use case is. A portable generator with a 50 amp 220 VAC connection to a Transfer switch tied into the house electrical service. Running the Generator unmodified made every dimmer controlled light bulb flash at a high rate. The same kind of bulbs in a Wemo on / off switch worked fine as did the C by GE bulbs in various lamps. My APC smartups and a backups connected to computers and other home devices were not happy either.
I found documentation for the transfer switch and the generator. The transfer switch document told of a ground neutral loop and the generator (Westinghouse W9500DF) user manual described how to modify the alternator wiring to prevent it. The manual also warned that doing so would disable the built-in GFI protection for the 20 amp outlets on the generator which is concerning if the generator is to be used by itself to power tools or the like.
I followed the instructions for my generator and removed a ground to neutral jumper. Having done so and testing, I discovered that my Wemo dimmers were no longer flickering when run on the generator power. further scrutiny of the dimmer lights showed that at 100 percent brightness, there was still a barely detectable flicker and at about 80 percent power was reduced beyond what I could see. My UPS devices were better but still not satisfied. I noted that the generator was out putting a AC frequency of 62.5 to 63 Hz. The UPS displays 60.0 Hz on line power. So its accurate enough. Using that frequency display I tweaked the governor until the generator was outputting AC at 60.0 Hz plus minus half a Hz. Seems that is as good at that machine gets. But it was good enough to satisfy the UPS devices. Problem solved.
I ought to note that I have a foundation in mechanics, electricity, electronics, and information technology. I know what I can do and just as importantly what I shouldn’t. The modification procedure was straight forward using only a 1/4 in drive and metric sockets but the potential for huge damage if done incorrectly is there. If in doubt, your better off having the modification performed my a service technician. Good judgment comes from experience and experience from poor judgment.

@Jerbear - hoping maybe you can offer me some additional advice, as your post is the only helpful thing I’ve read that closely resembles my current situation. I have a DuroMax XP13000EH generator and I’ve had it professionally converted to run off natural gas. I went to test it out today and noticed all of my LED recessed lights in the house were flickering. They’re running on GE Z-Wave smart dimmers. Connected through my Samsung SmartThings hub. I looked into the bonded neutral issue you described in your post and ended up removing the jumper from mine as well in hopes that it would resolve my issue. However, still no luck. I think they flickered even worse afterwards (but could be in my head). I don’t have a transfer switch. I have an interlock kit with a dedicated generator breaker installed directly in my electrical panel. All of my smart dimmers work fine on metered electricity from the utility provider. So I’m not sure why such a drastic difference running them on the generator. If it helps, I did notice the display on my generator said frequency was 63Hz. Could that be causing huge issues since it’s not exactly 60Hz? I wasn’t sure if 3Hz made a huge difference or not. Any help or troubleshooting tiles would be greatly appreciated.

Update on what I have learned since that post. My smart dimmers use LEDs. The fixtures had LED bulbs in them before I added the dimmers. I have no experience on incandescent bulbs with smart dimmer and generator. I am using WEMO smart switches and dimmers and also C by GE smart dimming bulbs in lamps. A have added surge protection to my main service panel and to the Reliant 50 Amp manual transfer switch. I have learned that the bounded neutral deal only matters to GFI circuits as a bonded neutral generator when connected to the house panel which is also grounded allows some return current down the generator to house ground which the GFI is sensitive to. I got a suitable 50 Amp unwired plug and bridged the Ground to Neutral to rebound the generator if it gets used stand alone. I figured the big plug because I won’t be using that one for power tools in the yard.
Like you my standby portable generator (Westinghouse 9500DF) was factory regulated no load at 63Hz as indicated by the generator front panel display and by my computer smart UPS. BTW 63 Hz caused the UPS to fail over onto battery. All my WEMO dimmers flicker even if the generator frequency is higher than 60.1 Hz. The C by GE smart bulbs do not flicker. LED bulbs do not flicker that I can see.
I got the house running on generator and loaded it up. There is an RPM limit stop screw which is easy to adjust plus the Generator has a frequency counter display which I used to turn the RPM/Frequency down to <= 60 Hz. The WEMO dimmer flickering was 99% eliminated. Can be frustrating because these machines operating frequency is load and temperature dependent. I observed frequency increasing a little after startup as it got up to operating temperature. This frequency thing is a moving target. What I have settled for is to tolerate an operating frequency of 58Hz - 60Hz. To get to that I started after warm up at about 60.5Hz which flickers the dimmers if they are on but after loading the generator up it settles in at <= 60Hz. Your results will vary I fear. The other WEMO On/Off switches do not flicker. Mechanical switched lights do not flicker. I wrote to WEMO with my observations. Who knows if they will do anything with that.