RCD Tripping Hell with high load

[Fletch]

Hi all. First time poster here with a hell of a lot less hair than I had 3 weeks ago now! so please be nice, I'll try and explain best I can. I am not a sparky but have some idea of electrics. I also own a multimeter.

Short version. 100A, 30mA RCD trips INTERMITTENTLY on WYLEX 8 fuse board when 'large load' is added (eg ~12A). It's not isolated to 1 MCB as can be cooker or inmersion or Hoover tripping RCD. Does it anytime of day. New immersion heater, new sockets throughout house same problem. Had an electrical safety test pass.

Longer storey.

Bought house in April. Had an electrician change all socket faces and carry out electrical test in doing so he found the RCD on the 'constant live' board (as we have eco 7 board for the storage heaters) had been bypassed. He reconnected it and since then (June) it's been tripping out left right and centre. I've worked out it happens when the load on the circuits is high, e.g. When the cooker AND the immersion is on, or when the heater and Hoover is turned on pulling more than say 10A and this can be across multiple MCBs. But all are ok if on individually. The immersion heater (3KW) is brand spanking new (like installed yesterday new as we were told it could be a leakage there (but we needed a new one anyway ) and the cooker is new ish too . So tripping hell for the last few months not solved by new immersion. Now Over the past 2 nights the RCD has tripped when, the cooker and immersion were on, when the kettle and immersion was on, when the lounger heater and cooker were on and the overnight when the off peak heating kicked in too, (so no hot water in morning) but only on the constant live RCB tripped as though the load of heaters and immersion is too high. There no issues with any low loading appliances such as lighting or phone chargers or plugs. But I'm sat here in bed now the immersion is on happy as Larry with no issues. Als FYI -There is not earth loop throughout the upstairs lighting .

Personal diagnosis:
I've spent days reading about N-E faults but they appear to be on a specific circuit, whereas my RCD Will trip even if the MCB for the last thing to cause the tripping is off... could that still be a N-E fault? I've also been round and unplugged everything (as the sparky did) and plugged things in individually and had no issues (including Hoover and putting just immersion/cooler on) utill putting more than one on.

Other one I've read about is a cummuliative earth leakage, which as the current load on the circuits goes up it exceeds the 30mA RCD value which I think personally is most likely but I don't have any clues on how to test this?!

I've read about broken RCDs too but everyone I've seen/read has said it won't be that.

We've spent a grand on electricians so far and are drastically running out of money, we feel a little as though the guy who did the safety test 'missed' something or didn't investigate properly, but he says it's all fine and can't see anything that would be causing it.

Hellllllllllllp! Is there anything I can do indivually with my trusty multimeter to see if I can work out just WTF is causing it?

I've uploaded a picture of my box setup. You can see that the cooker MCB Is off from last nights requirement for hot water but the immersion will still work with it on just so long as the cooker it's self isn't heating up.

Any help MASSIVELY appreciated.

Cheers

A Balding M

 

[Pete999]

Hi all. First time poster here with a hell of a lot less hair than I had 3 weeks ago now! so please be nice, I'll try and explain best I can. I am not a sparky but have some idea of electrics. I also own a multimeter.

Short version. 100A, 30mA RCD trips INTERMITTENTLY on WYLEX 8 fuse board when 'large load' is added (eg ~12A). It's not isolated to 1 MCB as can be cooker or inmersion or Hoover tripping RCD. Does it anytime of day. New immersion heater, new sockets throughout house same problem. Had an electrical safety test pass.

Longer storey.

Bought house in April. Had an electrician change all socket faces and carry out electrical test in doing so he found the RCD on the 'constant live' board (as we have eco 7 board for the storage heaters) had been bypassed. He reconnected it and since then (June) it's been tripping out left right and centre. I've worked out it happens when the load on the circuits is high, e.g. When the cooker AND the immersion is on, or when the heater and Hoover is turned on pulling more than say 10A and this can be across multiple MCBs. But all are ok if on individually. The immersion heater (3KW) is brand spanking new (like installed yesterday new as we were told it could be a leakage there (but we needed a new one anyway ) and the cooker is new ish too . So tripping hell for the last few months not solved by new immersion. Now Over the past 2 nights the RCD has tripped when, the cooker and immersion were on, when the kettle and immersion was on, when the lounger heater and cooker were on and the overnight when the off peak heating kicked in too, (so no hot water in morning) but only on the constant live RCB tripped as though the load of heaters and immersion is too high. There no issues with any low loading appliances such as lighting or phone chargers or plugs. But I'm sat here in bed now the immersion is on happy as Larry with no issues. Als FYI -There is not earth loop throughout the upstairs lighting .

Personal diagnosis:
I've spent days reading about N-E faults but they appear to be on a specific circuit, whereas my RCD Will trip even if the MCB for the last thing to cause the tripping is off... could that still be a N-E fault? I've also been round and unplugged everything (as the sparky did) and plugged things in individually and had no issues (including Hoover and putting just immersion/cooler on) utill putting more than one on.

Other one I've read about is a cummuliative earth leakage, which as the current load on the circuits goes up it exceeds the 30mA RCD value which I think personally is most likely but I don't have any clues on how to test this?!

I've read about broken RCDs too but everyone I've seen/read has said it won't be that.

We've spent a grand on electricians so far and are drastically running out of money, we feel a little as though the guy who did the safety test 'missed' something or didn't investigate properly, but he says it's all fine and can't see anything that would be causing it.

Hellllllllllllp! Is there anything I can do indivually with my trusty multimeter to see if I can work out just WTF is causing it?

I've uploaded a picture of my box setup. You can see that the cooker MCB Is off from last nights requirement for hot water but the immersion will still work with it on just so long as the cooker it's self isn't heating up.

Any help MASSIVELY appreciated.

Cheers

A Balding M

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When you say there is not an earth loop in the lighting upstairs, do you mean the lighting has no earth wires,( cpcs )?
Did your Electrician explain why the RCD had been bypassed? it seems that whoever bypassed the RCD did so because it was showing the same problems you are experiencing now.
When your Electrician did the "checks" on your installation, did he do any testing with a Multi Function Tester (MFT), and if so were any test results issued to you in the form of EICR? Sorry for all the questions, but with your problems, it's going to be questions, questions until someone can form an opinion as to what the problem may be, one more question, sorry, are there any specific times the RCD trips, for example is it only at night?

 

[Fletch]

When you say there is not an earth loop in the lighting upstairs, do you mean the lighting has no earth wires,( cpcs )?

Yeah the lighting circuits are just 2 core red and black cabling not new 3 core brown blue and green/yellow

 

[Midwest]

Welcome Fletch to the forum. Sorry to hear of your problem. All of those things you mentioned, could be the cause of your problem. Unfortunately for you, you current standard tariff has one RCD protecting all the sockets, cooker etc.

I'm afraid the only way to get to the bottom of this, is to employ a competent electrician to carry out suitable testing to locate the fault(s). Perhaps have an Electrical Installation Condition Report carried out, and even consider having your consumer unit replaced, when the fault has been located.

You are not going to rectify this issue yourself.

 

[Octopus]

There is little or nothing you or your trusty multi meter can do.

You need a local spark to properly test your RCD, test all the circuits INDIVIDUALLY for IR and have an earth leakage clamp meter.

 

[Octopus]

We've spent a grand on electricians so far and are drastically running out of money, we feel a little as though the guy who did the safety test 'missed' something or didn't investigate properly, but he says it's all fine and can't see anything that would be causing it.

Doing what? What certificates have they given you?

 

[Fletch]

I'm afraid the only way to get to the bottom of this, is to employ a competent electrician to carry out suitable testing to locate the fault(s). Perhaps have an Electrical Installation Condition Report carried out, and even consider having your consumer unit replaced, when the fault has been located.

You are not going to rectify this issue yourself.

*crying face* Ok,

Do you Any clues (even ball park figure) on the cost of an electrical installation condition report? 3 bed terrace.

 

[Octopus]

^^ from what you describe a EICR won't help.

Read my post #5 and get that done?

Unless you know the RCD is OK, the IR is OK and you haven't got excessive earth leakage, you won't move forward.....

One other point - it "could" be the incoming supply causing this.

 

[Fletch]

Doing what? What certificates have they given you?

Replaced all socket faces and installed some new sockets. Replaced all light fittings. Carried out electrical safety tests. Replaced earth rod (old one had too higher resistance). Installed earth to the copper piping in house, I have Certs for tests.

 

[Octopus]

^^ OK

So your "grand" has been spent on improvements ........... so its not wasted as such.

If you don't have faith in said spark, ask around locally , but when you call them, I would make sure they have an earth leakage clamp meter they can bring - not all "sparks" have these, and for faults as you describe they are essential.

 

[Pete999]

Hi all. First time poster here with a hell of a lot less hair than I had 3 weeks ago now! so please be nice, I'll try and explain best I can. I am not a sparky but have some idea of electrics. I also own a multimeter.

Short version. 100A, 30mA RCD trips INTERMITTENTLY on WYLEX 8 fuse board when 'large load' is added (eg ~12A). It's not isolated to 1 MCB as can be cooker or inmersion or Hoover tripping RCD. Does it anytime of day. New immersion heater, new sockets throughout house same problem. Had an electrical safety test pass.

Longer storey.

Bought house in April. Had an electrician change all socket faces and carry out electrical test in doing so he found the RCD on the 'constant live' board (as we have eco 7 board for the storage heaters) had been bypassed. He reconnected it and since then (June) it's been tripping out left right and centre. I've worked out it happens when the load on the circuits is high, e.g. When the cooker AND the immersion is on, or when the heater and Hoover is turned on pulling more than say 10A and this can be across multiple MCBs. But all are ok if on individually. The immersion heater (3KW) is brand spanking new (like installed yesterday new as we were told it could be a leakage there (but we needed a new one anyway ) and the cooker is new ish too . So tripping hell for the last few months not solved by new immersion. Now Over the past 2 nights the RCD has tripped when, the cooker and immersion were on, when the kettle and immersion was on, when the lounger heater and cooker were on and the overnight when the off peak heating kicked in too, (so no hot water in morning) but only on the constant live RCB tripped as though the load of heaters and immersion is too high. There no issues with any low loading appliances such as lighting or phone chargers or plugs. But I'm sat here in bed now the immersion is on happy as Larry with no issues. Als FYI -There is not earth loop throughout the upstairs lighting .

Personal diagnosis:
I've spent days reading about N-E faults but they appear to be on a specific circuit, whereas my RCD Will trip even if the MCB for the last thing to cause the tripping is off... could that still be a N-E fault? I've also been round and unplugged everything (as the sparky did) and plugged things in individually and had no issues (including Hoover and putting just immersion/cooler on) utill putting more than one on.

Other one I've read about is a cummuliative earth leakage, which as the current load on the circuits goes up it exceeds the 30mA RCD value which I think personally is most likely but I don't have any clues on how to test this?!

I've read about broken RCDs too but everyone I've seen/read has said it won't be that.

We've spent a grand on electricians so far and are drastically running out of money, we feel a little as though the guy who did the safety test 'missed' something or didn't investigate properly, but he says it's all fine and can't see anything that would be causing it.

Hellllllllllllp! Is there anything I can do indivually with my trusty multimeter to see if I can work out just WTF is causing it?

I've uploaded a picture of my box setup. You can see that the cooker MCB Is off from last nights requirement for hot water but the immersion will still work with it on just so long as the cooker it's self isn't heating up.

Any help MASSIVELY appreciated.

Cheers

A Balding M

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View attachment 38363

View attachment 38364

Fletch where are you based? as the code you have in your profile comes up all over the place?

 

[Fletch]

^^ OK

So your "grand" has been spent on improvements ........... so its not wasted as such.

If you don't have faith in said spark, ask around locally , but when you call them, I would make sure they have an earth leakage clamp meter they can bring - not all "sparks" have these, and for faults as you describe they are essential.

Magic.. don't work in north Wales do you Murdoch? Haha.

So your consensus is that there's an earth leakage on one of the circuits? Or more than one? If the latter causing a cumulative tripping level leakage?

 

[Fletch]

Fletch where are you based? as the code you have in your profile comes up all over the place?

Ll54 5sd is the postcode.. just south of caernarfon in north Wales.

 

[The Ghost]

Tracking RCD faults is notoriously difficult, personally I am always worried when I get called out for an RCD fault because it can be so many things and somtimes really obscure. The good news is there is a way to test methodically to assess what the problem is it just takes a very logical approach, good test gear and knowing how to use it. You have to measure in different ways the amount of leakage on any part, and all of the installation. As it has been said you need a decent electrician who knows how to do this. Suggest you specifically ask the electrician "Can you track down RCD problem?" You will have to use your nous to divine whether they sound competent or not. I would guess it cannot take more than a day to find the fault, but normally should be quicker.
I might guess that the element is going on your cooker and the symptom is sub clinical so to speak before it becomes full blown cooker circuit blowing. As you say it seems there is cumulative earth leakage identified to cooker and immersion, maybe also other equipment. A ramp test can show how much is leaking from each appliance with a bit of basic maths.

 

[Octopus]

Magic.. don't work in north Wales do you Murdoch? Haha.

So your consensus is that there's an earth leakage on one of the circuits? Or more than one? If the latter causing a cumulative tripping level leakage?

I rarely drive more than 10 miles, let alone 200!

I'm only speculating - and I'm well know for HATING up front RCD's and dual RCD boards.

If and I say if you decide to go for a new fuse board, just remember, one using RCBO's will be more expensive to install, but only individual circuits will trip, so resulting issues down the line will be far easier and cheaper to locate