Multiple Z-Wave Dimmers Dying Completely (no manual operation, either)

SYNOPSIS: I have one circuit in my house that has killed three Z-Wave 600 Watt dimmers (two Honeywell, one GE, all made by Jasco) in quick succession and I don’t know why. The Z-wave dimmer is on a two-way circuit that controls a pair of outdoor porch lights.

GORY DETAIL: I installed the first Honeywell (Jasco) Z-Wave Plus Smart Light Dimmer Switch (Model 39351) in August 2018. It worked reliably for about four months. Then, when were away in December, I saw “Not available” for that light in the Samsung Connect (Classic) app.

When I returned home, the blue LED light on the switch was out and the switch would not operate the light manually. I killed the breaker and left it off for a while. After restoring power, the switch didn’t come back on. The air gap switch doesn’t restore the dimmer.

I replaced the bad dimmer with an identical spare Honeywell dimmer. The blue LED came on, the switch was visible in the Connect app, the porch light came on, the switch operated manually as it should. After about two minutes of normal operation, the problem recurred: the outdoor light went out, the blue LED went off, it stopped responding to manual control, and it is not discoverable on the network. It just died quietly without any flash, noise or smoke. There was steady 121.6 VAC at the switch; no voltage spikes or reductions were visible in the house; none of the house lights were flickering. Power seems to have stable and well regulated.

Thinking that maybe I got a bad batch of Honeywell dimmers, I bought and installed a GE dimmer (also made by Jasco and identical to the Honeywell dimmers) at Lowe’s. Upon power-up, the porch light went on and the manual switch worked correctly. I was able to rename it in the Connect (Classic) app and save the name change. Three minutes after powering the switch, I went to the “Things” location in the app and saw it was “Not available" – the dimmer had died quietly just like the second Honeywell switch. The blue LED was out, the porch light was out again and switch was dead. Power was steady and there were no storms that might have caused spikes.

I have about 15 other Z-Wave devices in the house and all are working correctly and none have failed. Seven are wired-in switches and dimmers; four are plug-in switches; two are outdoor plug-in switches; and two are battery operated. I don’t think any of these other devices are on the same circuit as the failing dimmer switch, but I’m not 100% positive about that. Unfortunately, I don’t have my house circuit diagram with me at the moment, so I don’t know what else is on the circuit.

The circuit breaker providing power to the circuit is a tandem, so I suspect some circuit modification or addition has been done in the past (we’ve owned the house for 9 months). The breaker does not blow when the dimmer fails.

The switch is wired correctly to hot, neutral, load, and ground. The switch is in a three-gang junction box and there are three different circuits in the box. I’m quite certain that the correct neutral is wired to the switch, but not 100% positive about that. It could be I’m using a neutral from another circuit (bad practice for safety / backfeed reasons), but I don’t think that is the case. I don’t believe that should affect the dimmer as all neutrals are joined on the ground bus bar in the panel.

When we bought the house, this porch light was controlled by a Lutron dimmer/timer switch which I believe operated correctly there for years using the same neutral.

An electrician who has done work for me before has seen something similar with other electronic devices caused by water ingress into a circuit. I haven’t yet checked the porch lights for water. We DID have a huge problem with Christmas lights tripping off a GFCI this past season due to water ingress during rain storms.

Any idea what is going on here? This is really odd and frustrating behavior and I’m at a complete loss here. Anybody have an idea?

Jasco requested one that I send them one of the failed switches for inspection and that is underway.

Honeywell Z-Wave Plus Dimmer - Amazon

Honeywell Z-Wave Plus Dimmer - Jasco

I’m sure that’s very frustrating. :disappointed_relieved: If it doesn’t work manually, it’s an electrical problem, not a network problem. Water seepage seems like a reasonable guess, but you would just have to do the same diagnostics as if it was a dumb switch. Since the Lutron probably doesn’t require a neutral, it could even be that it is only the neutral part of the circuit that has the fault.

Thanks. Because the neutral is grounded at the panel, I don’t think it would be the problem. But I wonder how a small current leakage to ground on the load side would make this happen. It will be interesting to see what Jasco finds when they tear down the dimmers.

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Out of curiosity, what lights or other devices are connected on the load side?

I think I agree with Tony’s line of thinking…what are you controlling? I have a suspicion that is is an LED fixture that has a failing PSU that is frying your dimmer and/or isn’t designed to dim.

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Only two outdoor porch lights, one on either side of French doors. They are regular outdoor porch fixtures mounted on the wall. They had Frosted Candelabra LED Bulbs in the fixtures, but I changed those to Rough Service 60W incandescent bulbs after the first switch failure.

Switches #2 and #3 failed with the incandescent bulbs.

Robert, see my response to Tony. I also thought maybe the LED bulbs were causing the problem, so I switched to incandescent and still blew two switches!

The first switch ran fine with the LED bulbs for about four months. The original Lutron switch ran fine with the LED bulbs for some years (maybe ten).

The Honeywell and the GE switches both went out after just a couple of minutes operation with the incadescent bulbs.

Well, my next step would be to remove all lamps (bulbs) and then grab a multi meter. See if there is any continuity reading between the hot, neutral, and ground of that load. Anything less than infinity would be highly suspect. If that checks out, make sure there is no voltage between the neutral and ground when the circuit is live and the lamps are lit (do I have to mention to be really, really careful here??).

@JDRoberts @rjwerth @TonyFleisher – Gents, thanks for your help on this. I finally got around to trouble-shooting this last week. I had an electrician installing some new circuits and he took a look at the problem switch. He noticed the load-side had a pigtail connected to the switch and then the load wire split to to wires, one going up in the wall and one going down in the wall. The Up wire fed the two outdoor porch lights. The Down wire went to the crawl space and (we think) fed two step-lights built into the porch concrete steps. The two porch lights were completely dry. BUT, the gaskets on the 28 year old step lights had failed and they had lots of water and moss growing inside them. These step lights typically have snow on them throughout the entire winter, so lots of opportunity for water entry. I had pulled the translucent covers off the step lights last summer and I didn’t replace the gaskets, so this probably created a new water entry point into the lights.

To fix it, we pulled the Down (step light) wire off the pigtail and taped it off, then connected only the two wall-mounted porch lights on the wall to the switch. In other words, the switch is now only feeding the two wall-mounted lights. The wall porch lights have been running for four days now with no problems.

I’m kicking myself for not noticing that the load line split into two with one going UP to the porch wall lights and one going DOWN to the step lights cast into the concrete porch.

Thanks again.

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