Shelly Bypass Exploded

  • I had 3 Shelly bypass installed for a Shelly 1L and Shelly Dimmer 2 connection without neutral.

    Today one of the Shelly bypass exploded while lights were turned off. I have now uninstalled the other two and I will not install these bypass devices in the future, as I have lost confidence in the devices.

    Anyone experienced the same issue?

  • which bypass was destroyed? the one on Dimmer2 or the one on the 1L?

    Is there more information? Sketch / photos of the wiring, connected loads, etc.

    On a Shelly 1L.

    I didn’t take any pictures of the mess, just cleaned it.

    Wiring was done according to the instructions (bypass between phase and neutral feeding the load), everything was working fine for weeks until this happened out of nowhere...

  • Exactly the same thing just happened width me. :(
    I used shelly bypass with shelly 1L. One switch, two lights. The setup was working for weeks, and now it just exploded.. :(

  • Open a ticket be allterco.



    9x Shelly 2.5 ; 18x Shelly1; 2x Shelly 1L mit Bypass und Einschaltstrombegrenzer; 2 x D/W2; 2 x Shelly Plug S, 1x shelly dimmer und 1 Shelly H&T über Cloud, APP und Alexa gesteuert.8o8o8o

    9 x Shelly 2,5 und 4 x Shelly1 fremd verbaut, inkl. Cloud und Alexa Sprachsteuerung.

    Jeder so wie er kann!  :D

  • Any safer alternatives for this device?

    Shelly Bypass temperature always 80+C and i don't like something is so hot in my ceiling.

  • I testing 1L with Fibaro Bypass 2.

    24h passed, everything looks fine. No flickering, no freezing.

    Fibaro Bypass 2 temperature is room temperature. Looks much safer.

  • not sure why 1L needs bypass anyway.. its just an on / off relay... bypass is useful in dimmers when load is too small but for on/off relay like 1L i dont think its needed anyway.. unless i'm missing something

  • Hi

    Per my understanding it needs a bypass on small loads (<20W) because it doesnt have its own N and it feeds off the small current running through the load. If the load is to small you need to increase the current using the bypass. If you wire it so it has its own N, then you dont need the bypass.

    I think a resistor should also work as a bypass, provided you use one, with high enough power rating to safely disipate the heat.

  • Slightly different but on the same scary note.

    I have had 2 Shelly 1L’s explode in the last 24 hours. Both wired correctly and had been working without issue for a few hours, if relevant (as I think in my case it may be) they were wired to 2x 35w Florescent tubes. Neutral line wired.

    Both were working via manual switch and app, one went up in smoke after reapplying power to the mains ring after having had the trip switch off while doing some completely unrelated work elsewhere in the house, I flipped the fuse back on and noted puff of smoke from the switch.

    Replaced it with new and again all working via switch and app. Tested several times without issue, on about the 5 or 6 switching via the physical switch it went bang and scared the life out of me, tripped out the main building and is a charred black mess.

    Just to point out I am an auto electrician by trade so not an electrician but more than competent at wiring, but more importantly before anyone suggest this was a wiring and or connection issue on both occasions the Shelly and switch was already wired and had been working correctly initially until it decided to blow up.

    I wonder if they don’t truly support fluorescent tubes as the other 1L,s I have running led bulbs I have never had an issue with.

    But my thoughts on removing all hardwired Shelly devices from my house is growing as I don’t currently feel safe with these still connected.

  • Hi and welcome to the forum.

    if relevant (as I think in my case it may be) they were wired to 2x 35w Florescent tubes. Neutral line wired.

    Why a bypass? :/

    You need a bypass only if

    • load is to small
    • you have no N

    Both you haven't. ;)