Fuse box w/smart meter tripping overnight, help needed!


Hi all,

I've had a recurring problem with my fuse box RCD tripswitch tripping overnight and I'm wracking my brains to find out what's causing it; thought I'd post something here to see if anyone had similar problems before I fork out for a leccy.

We're with OVO and have had our smart-meter for about a year, which replaced our old manual meter. Our fusebox is a Memera 2000 and the RCD protects our shower, water heater (defunct as we use a combi boiler which is wired to the main supply) and sockets (all on seperate trip switches). During the night the RCD switch will trip which knocks out our power so I have to turn it back on manually in the morning.

I've used the OVO energy tracker to trace the problem to when it started on 14/06, where we had readouts of 0.0kwh at 2.00am. It's a pretty consistent pattern with a few minor variations which I've listed below

19/06 4am, 20/06 1.30am, 22/06 2.30am, 23/06 2.30am, 2/07 13pm, 3/07 3am, 6/07 2.30am, 7/07 4.30am and 8/07 4.30am.

I've gone through several steps to try and isolate the problem such as
* turning off all appliances overnight
* isolating shower, water heater trip switches (can't do sockets as that controls the fridge)
* bought a new fridge to replace old one
* ran new fridge through extension cable to different plug socket overnight
* turned off combi boiler overnight
* turned off house thermostat overnight

But nothing seems to be working. I'm considering the possibility it's the fuse box itself, or possibly the smart meter, but considering it happens around the same time most nights I'm thinking there must be something on a timer that starts running an unusual currant around that time in the morning. Can anyone help me out as I want to know everything I can before I have to get an electrician in?? Thanks in advance.

22 replies

Just a few thoughts - its mostly happening at night?

Mice or other pests chewing on a cable or otherwise interfering with a cable or socket/connection?

Loose electrical connection inside one of your sockets or a junction box somewhere?

It sounds like you have ruled out everything connecting to your wiring/ring main by switching them off in turn.
I thought it could be pests but the fact that the timing of the cuts is around the same exact time (2.30 and 4.30 usually) makes me think maybe not, though tbf I haven't ruled it out at this point! I just noticed the clock on my combi boiler was set to between 12am and 7am (though the timer switch has been set to off off the entire time so shouldn't really matter) so have turned all timers on the boiler off too in case it was trying to use the heating at night. Not sold on it being that though!
It sounds like more detective work is needed.

I am not familar with the energy tracker as I dont have a smart meter. Are the times it measures exact or does it just log an event to the nearest 1/2 hour? So if something happens at 4.05am it records it at the next log at 4.30am?
Yes it rounds to the closest half hour so could potentially be a pest issue if it were happening say between 2 and 2.30.
Unless you can find another cause it is probably a good idea to get your wiring inspected for any signs of damage and tested to ensure everything is safe.

If you do have a mouse or other pest issue they can be hard to find. My cats occasionally bring a live mouse into the house and let them go. There are a number of traps including humane ones which can catch them. Mice can get into some incredibly small spaces. I have seen one get through gaps about 1 to 1.5cm in size. They will also chew on anything- especially if they are hungry - this includes wiring, there are lots of stories on Google.

Also a few years ago I had an electrician visit my mothers house to test all the electrics, he found a dead mumified mouse inside the metal box in the wall behind and electrical socket! I have no idea how it got there.
That's certainly food for thought! The wiring in our ex- council house is definitely not gold standard (and is a downright hatchet job in places) so I dread to think what's behind the walls!

I've done a bit more sleuthing and another outside suspect may be RF from the smart meter interfering with the RCD; although it would be a bit strange it would happen now since it was installed in 2017 and we've gone nearly two years with no obvious issues. Does anyone know if the smart meters send particularly strong transmissions to OVO during the wee hours? In any case it's looking like I'll need a certified spark to safety test it all...
I doubt the signals are strong enough and there must be many cases of smart meters being installed close to fuse boxes. However @Transparent is a smart meter expert so, will probably be able to give a better answer than me.
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Ah... I've just been prodded awake by @Phil_H !

Firstly @cc86 I need more info. I went to your Forum Profile and found it blank. Please fill it out, but also state here
  • Is your Smart Meter SMETS1?
  • Whereabouts are you in the country? (I need to know your DNO)
  • How far away is your substation?
  • Does your house have its own earth stake (or is your supply PME)?
At the moment I believe OVO send "Readings requests" to Smart Meters once per day, shortly after midnight.

Nevertheless the way in which a Smart Meter communicates with the Wide Area Network (WAN) uses radio signals that are far too low-power to have any effect on an RCD. Less than 1 watt is used for both WAN and HAN transceivers on a SMETS2 meter.

My first thought is to consider mains-borne transients, possibly derived from a source outside of your house, such as maintenance on sub-station switch-gear.

I'm in a rural area where transients can be induced into overhead supply cables from nearby lightning strikes. I also have renewable-energy generation items stuck up high, and I'm on a hilltop.

I use transient suppressors hard-wired into my mains and the low-voltage input from renewable power devices, with nice fat earthing wires to take excess energy to ground. The mains ones I prefer each have 40kA capacity, will start operating within a few nS and are self-healing rather than sacrificial.

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Hi @Phil_H - unfortunately I'm not an expert in internal electrics, but someone else here on the Forum certainly might be able to help!
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Actually @Nancy_OVO - there is something you could check for us please...

Although we don't yet know which generation of smart meter is installed at @cc86's home, could you ask the SMETS team if there are time-stamps on the SMETS2 readings that OVO retrieve from the bowl?

If so, do these show the time at which the Communications Hub transmitted the readings?

Thanks.
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Hi @Transparent - yes there is a timestamp against each reading on the BOL. I'm finding out if this relates to the time it was sent or the time it was received.
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Ah... so it's a BOL is it?

I was wondering why OVO Staff kept calling it a "bowl" when Forum Members visited you at Bristol last month.

So I've just looked it up, and it seems BOL refers to the Business Orchestration Layer. The SMETS nomenclature is exactly self-explanatory is it? 😝
Ah... I've just been prodded awake by @Phil_H !

Firstly @cc86 I need more info. I went to your Forum Profile and found it blank. Please fill it out, but also state here
  • Is your Smart Meter SMETS1?
  • Whereabouts are you in the country? (I need to know your DNO)
  • How far away is your substation?
  • Does your house have its own earth stake (or is your supply PME)?
At the moment I believe OVO
send "Readings requests" to Smart Meters

once per day, shortly after midnight.

Nevertheless the way in which a Smart Meter
communicates with the Wide Area Network (WAN) uses radio signals that are far too low-power to have any effect on an RCD. Less than 1 watt is used for both WAN and HAN

transceivers on a SMETS2 meter

.

My first thought is to consider mains-borne transients, possibly derived from a source outside of your house, such as maintenance on sub-station switch-gear.

I'm in a rural area where transients can be induced into overhead supply cables from nearby lightning strikes. I also have renewable-energy generation items stuck up high, and I'm on a hilltop.

I use transient suppressors hard-wired into my mains and the low-voltage input from renewable power devices, with nice fat earthing wires to take excess energy to ground. The mains ones I prefer each have 40kA capacity, will start operating within a few nS and are self-healing rather than sacrificial.



Thanks Transparent I created my forum profile in a hurry and forgot to fill out the profile info, will do that and nudge you back, thanks for the responses everyone!
Profile is updated now.

@Transparent I live in Aberystwyth, from googling the nearest substation is up by the University at least a mile away from me, smart meter is a Liberty 100 type code: MAX10Z and the house has an earth stake which I'll photo for you as well as the meter. (If you're wondering about the tissue paper stuck to the pipe at the bottom that was there when I moved in, it's been sealed with what looks like black tar and looks exactly that bad in real life 🤦

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Top engagement and peer to peer help here @Transparent, @PeterR1947, @cc86. I'm on the same page as @Nancy_OVO, I can just about locate my consumer unit so I doubt I'd be able to offer any helpful advice here 😂

I hope you reach a conclusion soon, @cc86!
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That earth “spike” looks to me like an old water pipe and the connection looks dodgy as does the connector block joining all the earth leads together. If it was me, I would clean up the earth connection on the water pipe if there’s enough cable and replace the clip, also replace the connector block, ensuring that the cables are clean, maybe strip back 1cm to ensure a good connection. What do you think @Transparent ?
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Well firstly @cc86 those photos are just what we needed! Thank you.

I agree with @PeterR1947 that the water pipe connector is below any standard you might wish to apply!

But I don't think it's the earth-stake for the property. That type of clamp-fixing is more indicative of an old earth-bonding to a pipe for safety reasons.

It looks to me that there are six "earth wires" connected together at the earth block next to the 100A Service Fuse.



It's most likely that A is the connection to the consumer unit above.

B & C are the ones we need to know more about.
The most likely scenario is that one goes to the incomer of the gas pipe as it enters the house, and the other goes to an earth stake.

Are you able to shed any more light on these?
A runs behind the wooden panel and up to the consumer unit, B runs under the concrete floor and C runs under our stairs. I haven't seen an earth stake anywhere. Probably worth mentioning the gas meter is located behind this wall outside the property too ! Will send you a couple more photos for now and try to do some more investigation into it in the morning.

Thanks so much for your help so far everyone, my electrical knowledge is pretty basic so having help working out this problem is much appreciated and the customer support on here has been fantastic 😊

C runs through into the downstairs bathroom to earth the sink by the looks of it.
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Hmm... nothing too unusual here. Apart from the messy arrangement of earth wires and possibility of paint causing poor connections, it does seem that the wires are going where I'd expect them to.

I'm now assuming that your house is fed from a substation which is labelled PME. In this arrangement houses don't have their own earth stake. Earth is provided via the neutral wire which is grounded at the substation itself.

That is the reason for this wire here, D, which emerges from the bottom end of the Service Fuse enclosure


It obviously shouldn't ever have been sleeved in red(!).

If this was my house, I'd remove each earth connection, one at a time, check that there was indeed a good connection to copper, and then screw it back again. I'd probably replace the two pipe connectors you've shown us, and use some fine abrasive paper to remove any tarnish or paint from the pipes they clamp to.


The higher quality exterior-grade earth clamps cost 74p each from Toolstation (part 28619).

You could then engage an electrician to do a safety earth check. But you don't want to be paying him ££s to be abrade old paint off pipes. So let's get that done first!
OK will get onto my landlord about that, will send you photos of the earthing connections by the downstairs bathroom sink would you recommend doing the same to these?

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Yes, I really don't like these earth bonding connections being painted over. You can't tell whether paint has been pulled into a small gap between the strap and the pipe, thus impairing the connection.

If the landlord decides to call in an electrician, then he will also be able to test the tripping point of the problematic rcd. The test meter is a standard piece of kit for any certified electrician.

The RCD is rated at a nominal 30mA. Thus if the current flowing out through the live varies from that returning through the neutral by 30mA or more, then the trip should open.

In practice, all wiring and all appliances have a certain amount of leakage.
your kettle might have 2mA leakage
and your washing machine 1.3mA
the older wiring may itself contribute a further 5mA
etc.

So a typical installation may be operating at 20mA leakage or more before any "fault condition" occurs.

The electrician will be able to measure this, and also ensure that the trip operates sufficiently quickly to protect you.

Your landlord will, no doubt, already have a copy of the electrical safety certificate from the last annual check, and the parameters of the rcd test will be written on that.

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