A new smart meter is tripping RCD for 7 hours every night & I have a theory

[fearny26]

Hi guys I have this problem that I've been trying to figure out all week.

On friday I had a 5 tail economy 7 smart meter installed and every night at 2 am the RCD trips and you cant reset it until 9 am so the problem is obviously to do with the off peak supply coming on. Theres only 1 rcd for the whole circuit (i know, its an old setup) and 2 wylex fuseboards for on peak and off peak.

Now i was sure it had to be a problem with the meter setup because Ive never had faults before and I had the RCD tested on monday and thats fine. The energy company say its a problem at my end so I checked the EICR from 2018 and i saw that they didnt check the off peak board because i guess they were there in the day. So I figure maybe theres a fault on the off peak board then but why has it only shown up now? The board has been on but ive never used the storage heaters so its usually switched off at the board although I've never used any of the circuits I assumed the board functioned as the RCD had never tripped.

So, when they replaced the electric meter they also removed these old heating contactors that switched on the off peak supply and now all the meter tails come directly from the meter to the henley block and then to the RCD and fuseboards.

So my theory is that in fact both the off peak board and the heating contactor switch were faulty and so the off peak board was never live and thus the fault not detected, but with the new meter and the contactor removed the off peak board is receiving power for the first time and the fault is now present and trips the RCD for the 7 hours each night.

For reference the on peak board supplies everything in the flat bar the storage heater which I have never actually used.

There is nothing in the property switching on at that time and the off peak board is in fact switched off at the breaker, I've also tried unplugging and switching every isolator but the fault remains so I believe the faulty board could still be capable of tripping the RCD

I moved to the flat 11 months ago and had no problems previously whatsoever

I am sorry if its not explained well this is my first property and I am learning about all this for the first time and I'm just looking for some help because I'm having no power each night for a week now and the energy company cannot/will not help so any answers on here Im grateful for

I've attached a photo of the two wylex fuseboards and the RCD and henley block. Also are the old and new meters, my meter is top right with 2 tails going straight in and 2 feeding the old heating contactor that I think was broken in the bottom right

Thanks
Jake

 

[littlespark]

Any forum members down that way? I bet one of our experts could find the fault it in 10 minutes.

the eicr should have picked up faults on both boards. It’s mainly a dead test and visual inspection. The fact that the off peak board was off shouldn’t have stopped them.

is it tripping with the off peak mainswitch off?

 

[James18288]

Unfortunately it’s nothing to do with the supplier/DNO as the fault is on your equipment.

It’s hard to see from your photos. What have you been provided meter wise? Do you still have 2 seperate, or are both tariffs supplied from one? do both boards share one neutral from the new meter? Does the RCD provide additional protection for both consumer units or just the main CU?

My money would be on Some sort of neutral issue, possibly neutral has been split after the RCD. Looks like one has been terminated in a Henley next to the meter. I’d check where the neutral from the meter runs for a start and if/where it splits.
but without decent knowledge and an MFT it will be very hard to diagnose.

 

[fearny26]

Any forum members down that way? I bet one of our experts could find the fault it in 10 minutes.

the eicr should have picked up faults on both boards. It’s mainly a dead test and visual inspection. The fact that the off peak board was off shouldn’t have stopped them.

is it tripping with the off peak mainswitch off?

I've got a spark coming tomorrow hopefully to try disconnecting the off peak board see if that stops the trip

The only reason I wasn't sure about the EICR is because in the testing page it notes "off peak supply unable to live test" for the tests 1 to 3

Yes the off peak board is switched off when the RCD trips. I cannot reset the RCD for the 7 hour period each night which is why I think it has to linked to the off peak meter supply, could there be a bad meter tail perhaps and not the board?
[automerge]1598633758[/automerge]

Unfortunately it’s nothing to do with the supplier/DNO as the fault is on your equipment.

It’s hard to see from your photos. What have you been provided meter wise? Do you still have 2 seperate, or are both tariffs supplied from one? do both boards share one neutral from the new meter? Does the RCD provide additional protection for both consumer units or just the main CU?

My money would be on Some sort of neutral issue, possibly neutral has been split after the RCD. Looks like one has been terminated in a Henley next to the meter. I’d check where the neutral from the meter runs for a start and if/where it splits.
but without decent knowledge and an MFT it will be very hard to diagnose.

My meter is middle of the photo is 5 port dual tariff meter and both on and off peak supply come directly from the meter. There is the 2 incoming tails live/netural entering from the left (blue/brown) followed by 3 tails( 2 live and one shared neutral) entering the henley block in my ennclosure.

From the henley block I'm sorry I can't say for sure if the RCD covers both boards I don't know how to tell which cables which on a henley block I can tell you that each wylex fuseboard has a live and neutral cable and the RCD has one live and neutral.

Previously the meter had the on peak CU return neutral and the heating contactor had the return neutral for the off peak CU now it seems to share the one tail directly to the meter

It looks as you say that now there is only one neutral returning to the meter and the other is terminated into a new henley block installed with the meter. Could this be the issue

Again apologies if I am explaining this bad I am a long,long way from being any kind of electrician

 

[telectrix]

was a thread recently where the suspect is the smart meter transmitting and tripping the RCD. shielding with foil seems to have cured it.

 

[fearny26]

was a thread recently where the suspect is the smart meter transmitting and tripping the RCD. shielding with foil seems to have cured it.

Sorry I forgot to add on wednesday they sent out an engineer who just took the smart meter out and replaced it with a dumb meter but the fault remains so it must be something to do with changing from having the seperate heating contactor to the off peak being fed direct from the meter but I also saw what you're talking about to

 

[littlespark]

Please keep us informed with what the electrician finds.
although I would think meter fitters would be able to figure it out.....

Or maybe not

 

[pc1966]

As the others have said the fault will be on your side of the meter, and is probably:

1. An N-E fault that has only become apparent with the change in supply having altered the usually-small N-E voltage enough to cause a trip-level current to flow, or;
2. The off-peak board is now being energised (but before was not) and so tripping things.

It might be a fault that the original EICR did not pick up on, or it might be something more recent that has failed but did not manifest until the meter change (quite typical of N-E faults, they are usually a pain to find in the majority of cases with only 1 or 2 RCD that share several circuits).

 

[fearny26]

As the others have said the fault will be on your side of the meter, and is probably:

1. An N-E fault that has only become apparent with the change in supply having altered the usually-small N-E voltage enough to cause a trip-level current to flow, or;
2. The off-peak board is now being energised (but before was not) and so tripping things.

It might be a fault that the original EICR did not pick up on, or it might be something more recent that has failed but did not manifest until the meter change (quite typical of N-E faults, they are usually a pain to find in the majority of cases with only 1 or 2 RCD that share several circuits).

If the off peak board is switched off at the breaker can it still trip the RCD?

I have experimented and switching the off peak board on and off during the 7 hour period when the RCD cannot be reset and it doesnt change the situation the fault remains whether the board is on or off, its only when i switch off the on peak CU that I can reset the RCD and when I switch the on peak CU back on it immediately trips. The on peak CU runs everything except storage heater which is unused.

I also tried unplugging everything and turning off all appliances at the isolator cooker/shower etc, I've found that with everything off and unplugged it will reset but the moment I turn any plug or appliance or light or any circuit on it trips the RCD.

This however does not happen outside of the 7 hour period and has certainly never happened before the meter exchange so whatever is changing on the circuit has to do with the off peak supply going live.

Do you think the difference in current tripping the RCD is because there is now a shared neutral when there wasn't before perhaps?

 

[snowhead]

By the looks of it the one of the Neutral tails that originally went to the one of the Boards, is parked in the Henley type block below the meter to the bottom of picture 3.
That would mean one of the boards doesn't have a Neutral or both have been linled in the Henley to the right of the top Board

 

[James18288]

The fact the economy 7 CU had its own neutral but now is shared with the main CU would be where I’d look first. Where is the neutral supplied from in relation to the RCD? More than likely it’ll be a really easy fix. A N-E fault would probably trip whether the board had a live feed or not. Ie, not just at off peak times.
Hopefully you get it sorted tomorrow, and as has been said I’d be interested to hear what the fault was. Whatever happens though, could possibly be time at looking at an upgrade for those CUs

 

[snowhead]

Edit to above,
It looks like that parked tail was a Live which was switched by a now removed contactor for the Off peak and it's origin was in somewhere in the Henlys by the Consumer units

 

[fearny26]

The fact the economy 7 CU had its own neutral but now is shared with the main CU would be where I’d look first. Where is the neutral supplied from in relation to the RCD? More than likely it’ll be a really easy fix. A N-E fault would probably trip whether the board had a live feed or not. Ie, not just at off peak times.
Hopefully you get it sorted tomorrow, and as has been said I’d be interested to hear what the fault was. Whatever happens though, could possibly be time at looking at an upgrade for those CUs

Yes an upgrade would be ideal but the cost right now is less preferable ha.

Okay apologies for messy CU so setup is as follows

Of the four meter tails 2 enter the RCD at the top, one enters the middle back of the Henley and one enters the E7 CU directly.

Henley block is set out from left to right as follows
1 & 2 on the left are both tails From On peak CU
3 (rear middle) is meter tail
4 (front middle) goes to E7 CU
5 & 6 on the right enter the bottom of the RCD

On the meter side of things previously two tails came from the meter and two tails came from a seperate heat contactor now 3 tails come direct from the meter and one tail has been parked in a Henley block

Thanks guys for the replies so far

 

[littlespark]

Maybe I’m confused.
If the off peak board only supplies storage heaters, and you don’t use them, turn off the OP board if the rcd holds like that until spark has a look.

it could be a fault on any of the heater circuits, never mind on the tails.

 

[fearny26]

Maybe I’m confused.
If the off peak board only supplies storage heaters, and you don’t use them, turn off the OP board if the rcd holds like that until spark has a look.

it could be a fault on any of the heater circuits, never mind on the tails.

Yes the OP board is kept switched off but off or on the fault remains