Hi, looking for ideas please Recently had a kitchen extension, electrician extended kitchen ring (added a couple of sockets) , new appliances, extra lighting. He has added a new MCB to the consumer unit for the kitchen lighting. All safty tested and signed off with certificates 3 weeks ago the RCD tripped, lived here 15yrs and this has never happened. Sometimes have MCBs trip when a lightbulb fails but the RCD has never tripped. I reset it but couldn't spot an obvious reason so thought nothing more (not quite understanding the difference between RCD and MCB at that point). 2 weeks later happened again only this time it tripped 3x in about 15mins and then was fine 1 week later same again for 2 nights running, each time it is happening in the evening at roughly the same time (9ish) . Each time only device that has been on is the television but have all the other usual stuff plugged in on standby. Kitchen lights have been off each time. All new appliances seem to be working fine. Fridge/freezer does not seem to be tripping it when the motor kicks in The fact that this is happening at around the same time each night makes me think it is something on a timer. The only items are the heating which wasn't doing anything at that time and (if the picture shows) there is a 24hr timer switch above the consumer unit. This is for some outside floodlights which we never use. The 2 gang switch you can see switches them on and off , they are left off. The timer switch is also set to off but after the electrician had been one day the floodlights were switched on so I presume he had been seeing what they did. Switched them back off again. All the "pins" on the timer switch are set off as well. The other thing about this timer switch which I have only just noticed (having ignored it for 15years) is whilst it makes a mechanical ticking noise as if it should be working the dial does not actually move/the clock does not go round. You can manually move it but when left alone the time does not move on Could this be it? Is there something in the switch which would still trigger a problem at around the same time each night despite the clock not moving and it's own MCB (marked "outside")not tripping and the lights not switching on? Presumably something may have been disturbed when he added the new MCB or sitched the lights on for the first time in years. If I switch the lights on nothing trips Electrician is coming back to look at things but just looking for ideas
When your electrician added new lights, which side of the board has he added the lights to? was it the rcd side(left in your picture) or the non rcd side (right hand in your picture)
Ok so it sounds very much like an imbalance of the neutral, however this cannot be determined by this post alone as it needs deeper investigation, here are a couple of examples of what I would be looking at though just for fun. Have any of the new lights been joined into the original lighting somehow? borrowed neutral or jumped switch live in a switch, 2 gang switch that used to be a 1 gang switch, possibilities are endless. Neutral being wired into the wrong Neutral bar, not uncommon. Faulty appliance although highly unlikely, socket ring extended? Sounds like a likely cause depending on how this has been done. Could even be down to the RCD failing and on its way out,. I suspect not here though.
yes, lights have been joined into existing. Original switches are same but new switches added, ring for sockets has been extended. I have one of those plug in socket testers and all are reading fine. He tested and signed off circuits but I'm not sure what that involves. Think it's odd that it is always around the same time each night over a 10 minute period. Everything seems to work fine rest of day
There is your problem, the lighting in your picture shows the lighting is wired into your non rcd side, his lighting has been wired with a new breaker in the rcd side, you have got a Neutral imbalance on your lighting circuit causing the RCD to trip. You cannot mix up lighting circuits this way or you get what your experiencing now,
One of those plug in testers are good to see if your socket is correctly wired only, will not show anything else up but it is a useful tool.
electrician been, he tested the outside floodlight circuit . Got a reading of ?34 or 0.34??? think he was on neutral and earth when he tested it. Sorry I'm not sure what he was testing exactly but he reckons it's the likely fault. He disconnected the MCB which has disconnected the timer as well as the lights and an outside socket. There is some moisture in the lights but this is not new (though there has been quite heavy rain the last couple of weeks) . He reckons this is the best way as to test and find a fault can take hours so see how it is for now. Can't explain why it wold be around the same time every night if the timer switch wasn't working but we'll see what happens I guess
It could well be your outdoor lights, although why is it taking out your rcd when the lights looking at your board are on the non rcd side?
Complete shot in the dark from a chippie but do the pir's have a light sensor on them that activates around 9pm when it gets dark.
They do activate in the dark, or in the day if set for daylight operation. I think it was the outdoor lights that was causing it.
sorry, they aren't PIRs. They are huge floodlights. Apparently when the house was built 30 years ago it was a show house so they are for lighting the house up to show it off. Ridiculous things, never been used. Run from the timer (which as I say doesn't go round but makes a sound as if if should be going round) and further switched with that 2 gang box above the timer.
On the same circuit (which isn't operated by the timer) is an outside socket which appears to be working fine when I plug things into it however during the build they used a dumper truck to take out tons of earth and would have been back and forth right over where the cable is buried. ? Possibility. Though why it should only trip after dark at a similar time is beyond me
yep. There were plenty of dodgy things when we moved in, most of the rest sorted but only discovered today the socket was wired to this 16A circuit. Would run a hedge trimmer OK but rarely used it and they put a new outside socket on the extension as is in a better position. That said it did trip a few times when they plugged their cement mixer in during the build
Good lord, seems very odd but then if it was a show house it may have been a temporary socket for something and forgot about,
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