Green Building Forum - strange electrical failure Tue, 19 Dec 2023 04:19:41 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 strange electrical failure http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303771#Comment_303771 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303771#Comment_303771 Fri, 06 Oct 2023 14:49:06 +0100 djh
About 12:50 there was a loud pop and my computer went off. On investigation just one RCD and an associated MCB were tripped in one CU. The MCB is labelled correctly as "porch socket" and has a light and a Raspberry Pi powered from it. After a quick look around I turned the RCD back on. It stayed on and power came back where it was off. After another minute or so I turned the MCB back on. It too stayed on and the pi in the porch came back on. So I have no explanation for why the power went off!

Any thoughts?]]> strange electrical failure http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303772#Comment_303772 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303772#Comment_303772 Fri, 06 Oct 2023 16:31:01 +0100 WillInAberdeen
Mouse bit into a cable and was fried? I found several, mummified, they always look so surprised.

Drop of rain got into something, caused a spark to earth, evaporated?]]> strange electrical failure http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303773#Comment_303773 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303773#Comment_303773 Fri, 06 Oct 2023 17:07:28 +0100 djh Posted By: WillInAberdeenLightbulb blown?Dunno yet. The light is motion sensitive and only operates in the dark.

Mouse bit into a cable and was fried? I found several, mummified, they always look so surprised.
Not that I can see. I can't see any damage or extraneous creatures.

Drop of rain got into something, caused a spark to earth, evaporated?
No rain, but maybe moisture is a possibilty. It evaporated pretty quickly though.

Thanks for the ideas. Keep them coming :bigsmile:]]> strange electrical failure http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303776#Comment_303776 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303776#Comment_303776 Fri, 06 Oct 2023 18:54:15 +0100 DamonHD
Maybe just a transient on the incoming though?

Rgds

Damon]]> strange electrical failure http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303779#Comment_303779 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303779#Comment_303779 Fri, 06 Oct 2023 19:52:28 +0100 djh
Our PV comes in through the same CU, but it's not fed through an RCD. I forget the reason but I think the microinverters are pretty safe. There's two RCDs in that CU; one for three bathroom heater circuits and the other for a miscellaneous selection of things that happens to include the porch circuit. Just the latter tripped.]]> strange electrical failure http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303783#Comment_303783 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303783#Comment_303783 Sat, 07 Oct 2023 11:06:32 +0100 WillInAberdeen
@Damon, solar panels are prone to earth leakage trips because they look like big capacitors (big charged glass plates, mounted parallel to big grounded plates, such as a wet roof). Charging and discharging this 'capacitor' means the reactive current returning from the PV doesn't exactly match that supplied to it, which the RCD interprets as an earth leakage. Or there may be DC leaks at wet connections etc

The RCD might also be tripping because the inverter electronics store and subsequently release charge, as DC or as high harmonic frequencies, so the currents flowing in the live and neutral don't exactly match at all times.



Most houses have 'Type AC' RCDs fitted, but these are effectively banned under the new regs as they only work with pure 50hz AC and can be defeated by DC or harmonics. New RCDs are mostly 'Type A', but expensive 'Type B' should now be used for PV/EV/heatpumps etc with big power electronics. Maybe swapping out the RCD would help?]]> strange electrical failure http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303787#Comment_303787 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303787#Comment_303787 Sat, 07 Oct 2023 16:44:01 +0100 djh Posted By: WillInAberdeen@DJH, the more recent regs say householders have to be protected against shock if they bash a nail into any cable in their house.Our house was not built under those regulations! But in any case the downlead from the PV panels is SWA (in a conduit externally) and internal wiring is in the centre of the walls in designated directions from surface fittings.

AFAICT all the RCDs in the house appear to be Type AC (it's annoying/stupid that they don't say the type on them but just have little pictographs that you have to look up!) but we haven't seen any problems from our induction hob or washing machine or dishwasher. Maybe that was the reason for not fitting one to the PV.]]> strange electrical failure http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303794#Comment_303794 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303794#Comment_303794 Sat, 07 Oct 2023 19:44:42 +0100 owlman Posted By: djh
But in any case the downlead from the PV panels is SWA (in a conduit externally)

I assume you've got micro inverters?]]> strange electrical failure http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303797#Comment_303797 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303797#Comment_303797 Sat, 07 Oct 2023 20:48:13 +0100 djh Posted By: owlman
Posted By: djh
But in any case the downlead from the PV panels is SWA (in a conduit externally)

I assume you've got micro inverters?
Yes, as I mentioned up thread. :bigsmile:]]> strange electrical failure http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303801#Comment_303801 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303801#Comment_303801 Sat, 07 Oct 2023 21:39:34 +0100 owlman ]]> strange electrical failure http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303837#Comment_303837 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17988&Focus=303837#Comment_303837 Tue, 10 Oct 2023 23:32:35 +0100 Jeff B Posted By: WillInAberdeen@DJH, the more recent regs say householders have to be protected against shock if they bash a nail into any cable in their house. Usually this means every circuit is now put on a RCD including the PV. AIUI you are still allowed to protect the cables against nails by armouring or by burying them deeply in the wall or mounting them on the surface in plain sight, in which case RCD isn't required.

@Damon, solar panels are prone to earth leakage trips because they look like big capacitors (big charged glass plates, mounted parallel to big grounded plates, such as a wet roof). Charging and discharging this 'capacitor' means the reactive current returning from the PV doesn't exactly match that supplied to it, which the RCD interprets as an earth leakage. Or there may be DC leaks at wet connections etc

That's interesting. I have had a microinverter based solar PV system since 2011 (21 panels/microinverters). Up until about about 4 years ago we had suffered a total of six microinverter failures. Thankfully the cost was covered by a special warranty (10 years cover). With hindsight we realised that these events always coincided with the RCD tripping out in cold and damp winter days. Apparently the microinverters do not like being switched on and off and a local electrician suggested removing the RCD because, for the reason you say, i.e. if cables are surface mounted, (which mine are) then an RCD is not required. We have not had a single microinverter failure since!]]>