Electrical Circuit Tripping

[Greenmantle]

I have two consumer units. Each has about 10 RCB circuit breakers.
Bottom does sockets.
Top does lights and ancillaries.

The bottom one tripped 3 times yesterday and once today. None of the individual RCB breakers were tripped just the main unit switch.

The things that were plugged in and switched on were:
broadband router, network switches x 3 and wireless access points x2
laptops x 2, floor standing fans x2,
American fridge freezer, cooker range (not being used), smart meter monitor, Myzappi car charger (not being used).

I originally thought it was one of the fans since this issue only started last two days but now I am thinking it maybe the fridge freezer start relay.
Does anyone have any suggestions?

[119]

Freddie freezer wound be my guess.

Probably been working overtime these last few days!

[dhutch]

Greenmantle said:

I have two consumer units. Each has about 10 RCB circuit breakers.
Bottom does sockets.
Top does lights and ancillaries.

The bottom one tripped 3 times yesterday and once today. None of the individual RCB breakers were tripped just the main unit switch.

The things that were plugged in and switched on were:
broadband router, network switches x 3 and wireless access points x2
laptops x 2, floor standing fans x2,
American fridge freezer, cooker range (not being used), smart meter monitor, Myzappi car charger (not being used).

I originally thought it was one of the fans since this issue only started last two days but now I am thinking it maybe the fridge freezer start relay.
Does anyone have any suggestions?

Presumably the 'main switch' is an RCD, hence likely a fault to earth somewhere.
Slightly odd to have sockets on one, lights on the other, usually you would have half and half for better diversity/redundancy.

First thing to mention is unplugged is different to switched off, as typically the switch isnt only on the live and it could be a fault to neutral.
Second things that will get mentioned is the refrigerators are one of the key things than cant develop earth leakage faults, so dont rule that out.
Its currently dryish in most places, but if you have outdoor sockets or lights, maybe running a pond pump or something, thats another key one.
Spark ignitors on gas hobs are also not uncommon, the button fails, hob gets washed, etc. Or else ours just randomly trips always, we use a gas match now!

But otherwise its just a case of unplugging things and seeing if it stops, and or switching whole circuits off at the MCB and trying that, one of the reasons its a shame you dont have some sockets on the other board/RCD.. Although again the MCB is only on the live, you may or may not be comfortable taking the front off the consumer unit and pulling the circuits neutral wires out but thats the next step.

The other option is to get some RCBOs, if you board can take them, which gives circuits their own RCD protection and hence can narrow down the trip.

[Greenmantle]

Thanks for both replies. A fault to earth is highly likely. The house is 25 years old and I have lived in it all that time. The electrics have been rock solid.
Since my OP I have been just keeping a note of the time and date of each trip.
It averages out to 2 / 3 trips per day.
At one point I was convinced it was something external going on (at the substation) since I recorded three consecutive trips at 00:20.
I have scrubbed that one out now.
Anyway, last night I turned off all the circuits apart from 3 (kitchen, my bedroom and loft / alarm). It still tripped but at 04:30.
I'm going to price up swapping all circuits for RCBOs since I can do that myself (big switch at meter box will be OFF when I do this).
The leading culprit is still the American fridge / freezer which I will be able to shutdown next week and move contents to the half fridge that I don't use.
Hopefully I will have an update by Wednesday.

[eliot]

Greenmantle said:

I'm going to price up swapping all circuits for RCBOs since I can do that myself .

Changing the MCB's for RCBO's on an RCD fed consumer is wrong and I assume you aren't a qualfied spark.

If it's 25 years old - get the whole thing replaced with a regs compliant metal consumer unit with per circuit RCBO's and a surge protection (which of course you should use a spark for)

[Mr Pointy]

Greenmantle said:

Thanks for both replies. A fault to earth is highly likely. The house is 25 years old and I have lived in it all that time. The electrics have been rock solid.
Since my OP I have been just keeping a note of the time and date of each trip.
It averages out to 2 / 3 trips per day.
At one point I was convinced it was something external going on (at the substation) since I recorded three consecutive trips at 00:20.
I have scrubbed that one out now.
Anyway, last night I turned off all the circuits apart from 3 (kitchen, my bedroom and loft / alarm). It still tripped but at 04:30.
I'm going to price up swapping all circuits for RCBOs since I can do that myself (big switch at meter box will be OFF when I do this).
The leading culprit is still the American fridge / freezer which I will be able to shutdown next week and move contents to the half fridge that I don't use.
Hopefully I will have an update by Wednesday.

The fridge/freezer contents should be fine over night if you don't open the door so you could turn it off for 8 hours or so & see if you get tripping or not.

[TwistingMyMelon]

ANything with water would be my first port of call so Fridge Freezer...

[dhutch]

Mr Pointy said:

The fridge/freezer contents should be fine over night if you don't open the door so you could turn it off for 8 hours or so & see if you get tripping or not.

This is true. Especially if you have some coolbox blocks in the top drawer. And unplug it, don't just turn it off.

As said, shame there isn't a sockets circuit off the other board/rcd.