Z-Wave FGS-222 relay module - Popped and Tripped the MCB - Still works :/

[eveares]

So replaced the two old ugly X10 appliance light switches in my bedroom and installed a new Fibaro FGS-222 Z-Wave enabled relay module inside a 47mm dry-line back box along with a standard double switch for local control.

Pain in the *** to get it all in the back box and get the switch screwed on, but after a bit of fiddling and rearranging of the wires I manage it. Screws on relay module are also stupidly tiny and don't look like they will hold up for the job. (sure they will.

Being that I had cables for Feed In, Feed Out, Light 1, Light 2, I should of joined the feeds up outside the dry-line back box using a MFJB and had just a single feed into the dry-line back box - but managed to get it all in in the end as said.

Before screwing switch on:

View media item 98052
Anyway, screw the switch on, and re-energise the circuit. 6A Type B MCB immediately trips as I also hear a pop from my bedroom. RCD is unaffected.

I Immediate re-energise the MCB for a second time, this time everything appears normal; however I de-energise the circuit once again and check inside the switch to make sure everything is ok.

Below is what I got:

View media item 98053
Despite only tripping the MCB and not the RCD initially, and the black skid marks inside the back box; the module is fully functional and does not smell like burnt electronics at all.

Don't know where the short came from for sure, but there was one wire going to the switch from the module what looked slightly charged, so I of course replaced that and inspected around the charred area.

Maybe there was a short to the front of the earthed switch and the MCB tripped before the RCD could, and cleared the fault in the process.

Regards: Elliott

 

[deadshort]

Looks like you've been lucky ! the short must have been on the supply side of your expensive switch.

DS

 

[bernardgreen]

What a nightmare ! If you must have so much by the switch then at least leave the switch in a box by itself.

Put another back box above the switch for the "relay" andcover it with a blank cover plate

It isn't clear but I assume you do have an earth wire to the switches Earth terminal

and cleared the fault in the process

And may have damaged the unit in a way that it appears to work but may be over heating or otherwise.

Maybe the fault involved the wire that earths ( or did earth ) the metal switch plate. with that "fault " cleared ( earth wire blown away ) the switch plate is no longer earthed but hey the switch and "relay" still work.

 

[eveares]

Looks like you've been lucky ! the short must have been on the supply side of your expensive switch.

Indeed, at first I thought £42 had gone down the drain. Still can't work out exactly where the fault was, but as you said was likely upstream of the module. There is no charring on the module as can been seen.

Put another back box above the switch for the "relay" andcover it with a blank cover plate

Just filled in the plasterboard where the old X10 switch was as only wanted one visible switch.

It isn't clear but I assume you do have an earth wire to the switches Earth terminal

Yes of course. Can't do a L-N IR test while relay module is in circuit for obvious reasons. A R1+R2 test would also likely through odd readings back with the path through the module.

And may have damaged the unit in a way that it appears to work but may be over heating or otherwise.

Inspected, luckily the switch nor module does not feel warm....atm....but will keep an eye on it over the next week or so.

Maybe the fault involved the wire that earths ( or did earth ) the metal switch plate. with that "fault " cleared ( earth wire blown away ) the switch plate is no longer earthed but hey the switch and "relay" still work.

I know not recommended or reliable, but the R2 between the switch and my metal bedside fan (on different circuits of course) is 0.6Ω using my MM.

Can you get single back boxes deeper than 47mm?

 

[deadshort]

You could use a spacer frame the type you get with a dimmer switch to allow you to fit into a 16mm box.

Regards,

DS

 

[Iggifer]

Or
a) put a deep dry line box it
B) dress the cables a bit neater so there's room for the modules.

Wagos are great and all but I would not be trying to squeeze 3 x 6 ways in there as well as the module and switch. A small terminal block will be more than adequate and take up much less space

 

[eveares]

You could use a spacer frame the type you get with a dimmer switch to allow you to fit into a 16mm box.

But then it would not be flush.

a) put a deep dry line box it

Any known link to a dry-line back box deeper than 47mm?

Wagos are great and all but I would not be trying to squeeze 3 x 6 ways in there as well as the module and switch. A small terminal block will be more than adequate and take up much less space

Now why did I not think of that Will try that for any other similar switches in the future when there is more than two cables coming into the back-box.

 

[Iggifer]

I didn't realise it was a 47, looked like a 35 from the photo, but no, 47 will be the biggest you're gonna get.

 

[eveares]

I didn't realise it was a 47, looked like a 35 from the photo, but no, 47 will be the biggest you're gonna get.

inside a 47mm dry-line back box along with a standard double switch for local control.