A step you MUST TAKE with relays in humid environments

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I’ve got a Shelly +1 relay in a bathroom light fixture. The WAF has been dismal. She kept insisting the lights would flicker on and off like crazy and then go off while she is in the shower - but this happens randomly - not for three months, then 2 days in a row.

It never happens to anyone else and we could not figure out how to replicate it.

I replaced the fixture, the light switch, the wiring in between and the outlets in the bathroom. Still not resolved. An electrician came into our home and rechecked all the wiring, said it was well done and even admired the ferules used. He even stood in the bathroom with me with the shower running and could not replicate the issue.

I figured it out and it should always be taken into account with Shelly relays in humid bathrooms.

Determined to find the issue, I sat in the bathroom letting the shower to run for my a long time - and it happened again. Turns out the wife takes longer showers than the rest of us.

Any relay is highly sensitive to humidity and I found a quick inexpensive fix. Get a Ziploc bag and put several dessicant packets (from vitamin/medicine bottles) in it. Then put the Shelly in the bag as well, and pull all the wires into one corner of the bag and wrap electrical tape tightly around that. When putting the bag into the fixture, have the Shelly on one side of the bag and the desiccant packets in the other side of the bag, then fold it over to keep the Shelly and the desiccants away from each other. (There’s probably no problem with them touching but I’m just playing it safe, especially if a desiccant bag absorbs enough moisture to get wet - which should never happen in a sealed bag anyway.)

I sat in the bathroom running the shower with nothing but hot water and tolerating a long unwanted steam bath - until we ran out of hot water - and did that three times with no issue. Problem solved.

(The leak sensor did sound an alarm because the whole room was drenched - but that’s another story!)

Very inexpensive fix for a gnarly problem - but will have me in the doghouse for a long, long time!

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Nearly all electronic products have a “non-condensing” humidity specification. Shelly is no different:

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Another way to fix this is to conformal coat the PCB. Clear (no glitter) nail polish works well.

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@tom_l I believe your solution is the most robust but I didn’t want to take apart the shelly -

Also with regards to my solution - to make it really work as I see after a long time the dessicant being saturated if the bag is not a 100% complete seal - (which it isn’t as there is a gap between the bundled wires coming out of the bag - to then carefully seal that entire bundle of wires at the end of the bag with a nice big glob of silicone waterproof sealant that goes between all the wires. Sloppy but it works. Just be sure the bag doesn’t get any holes in it, if any tape touches the bag don’t pull it off :slight_smile:

Unrelated I guess but one thing I prefer is to always put the shelly’s in places where it is easier to replace the shelly. For example in places where appearance does not matter much such as the basement or garage (nowhere else for me), I have a hole in the receptacle for the wires to the shelly to go through. Then the shelly just hangs outside the fixture. 30 second replacement for a relay that would have to be replaced every 2 years or so instead of fussing around.