UK The RCD test button on my tester trips the wall sockets

[Lord Oddsocks]

We recently moved house (May 2024). The property is old (some >250 years), quite large with different outbuildings/extensions. From time to time the main power will trip (sockets not lighting). So I got out my cheap socket tester and all's well on various outlets, until that is I press the RCD TEST button and it trips back at the main "fuse" box.

Before I hire an electrician I wanted to check it wasn't something obvious we can check first.

The three main boards, each have stickers showing the electrical system was tested February 2024, with the next test scheduled in five years time. However we have had no work done of the property yet so this problem likely existed before we moved in - and all our applicances etc. were fine at the previous property.

 

[littlespark]

The test button on your tester is simulating a fault, and WILL trip the electric off.

This is what it’s supposed to do.

 

[Lord Oddsocks]

The test button on your tester is simulating a fault, and WILL trip the electric off.

This is what it’s supposed to do.

I'm please the tester is doing it's job and confirming there is a problem.

What I am trying to ascertain, since this test was performed at a number of different double sockets, is what the fault might be and what we could resonably check in the next few days before we can be at home next week to let an electrician inside.

I'm now assuming that the type of fault detected will not be due to anything specific connected to the sockets, but the main wiring itself. I'm hoping so because there are over 120 double wall sockets spread throughout all the buildings.

I'm assuming that there is potentially a serious safety issue too.

Thanks for your reply.

 

[PS Electrics]

We recently moved house (May 2024). The property is old (some >250 years), quite large with different outbuildings/extensions. From time to time the main power will trip (sockets not lighting). So I got out my cheap socket tester and all's well on various outlets, until that is I press the RCD TEST button and it trips back at the main "fuse" box.

Before I hire an electrician I wanted to check it wasn't something obvious we can check first.

Random trip events are the hardest to diagnose. When you say from time to time how often? I would suggest if you can to make a log of when it trips, weather conditions, what is connected and the time etc.

You can call out an electrician and they can do some tests on the wiring to see if it is anything obvious. But it could get costly if they have to do further investigations.

The three main boards, each have stickers showing the electrical system was tested February 2024, with the next test scheduled in five years time. However we have had no work done of the property yet so this problem likely existed before we moved in - and all our applicances etc. were fine at the previous property.

Did you have RCD protection for sockets at your previous property? If not then it could still be your appliances. Does this property have a split board with multiple circuits protected by an RCD? or individual RCBOs? Obviously lighting is not protected as you have mentioned that it doesn't cut out.

If it has multiple circuits protected by one RCD then it could be that the leakage currents for each circuit are putting you right on the threshold for the RCD and causing a random trip. An Electrician would also be able to look at this.

 

[Lord Oddsocks]

Random trip events are the hardest to diagnose. When you say from time to time how often? I would suggest if you can to make a log of when it trips, weather conditions, what is connected and the time etc.

You can call out an electrician and they can do some tests on the wiring to see if it is anything obvious. But it could get costly if they have to do further investigations.



Did you have RCD protection for sockets at your previous property? If not then it could still be your appliances. Does this property have a split board with multiple circuits protected by an RCD? or individual RCBOs? Obviously lighting is not protected as you have mentioned that it doesn't cut out.

If it has multiple circuits protected by one RCD then it could be that the leakage currents for each circuit are putting you right on the threshold for the RCD and causing a random trip. An Electrician would also be able to look at this.

I was afraid of this being random (we have the same problem diagnosing software issues in my IT business).

Previous property has RCD - and we still have that property - and my tester is OK. When I press the RCD TEST button there, the power stays on. But that's a much smaller site and electrics all less than 25 years old.

I like the thought of the wiring being on the threshold for the RCD in some way. It looks all very messy to me - and there is of course the connections to all the solar panels which is the first place we have had them. They were already installed by the previous owner - 30 odd large panels - on three seperate buildings - all seemingly linked back to the main board. I'm told that these and the battery storage, have meant we are 100% self-sufficient 24/7 the past 6 months!

This almost seems like a commercial site - and we should have a load of O&M stuff, diagrams and each switch and socket labelled - but we haven't.

Thanks for your reply.

 

[mainline]

I'm please the tester is doing it's job and confirming there is a problem.

The socket tester isn't confirming that you have a problem, its confirming that the rcd is tripping when your socket tester applies an imbalance.
You need an electrician to do some testing.

 

[littlespark]

if your rcd tester is not tripping the rcd at your other property, then im afraid, that property has a problem.

If it doesnt trip with the tester, it wont trip for an actual fault...

Do they all work on the test button on each rcd?


Please get an electrician in asap

 

[PS Electrics]

I was afraid of this being random (we have the same problem diagnosing software issues in my IT business).

The worst kind

Previous property has RCD - and we still have that property - and my tester is OK. When I press the RCD TEST button there, the power stays on. But that's a much smaller site and electrics all less than 25 years old.

It has nothing to do with the size and how old the electrics are. If your tester doesn't trip the RCD on your other property then you potentially have a dud RCD and therefore no RCD protection and therefore could be an appliance that is faulty but wasn't showing up in your old property. Does the test button work on the RCD in that property? Not fall proof on of itself but should be done yearly.

I like the thought of the wiring being on the threshold for the RCD in some way. It looks all very messy to me - and

Not the wiring, modern consumer electronics leak a small amount of current this adds up over multiple circuits.

 

[mainline]

Does the test button work on the RCD in that property? Not fall proof on of itself but should be done yearly.

Functional test every 6 months

 

[PS Electrics]

Functional test every 6 months

My Understanding is the 6 Months interval is IET Guidance and this wording is incorporated onto the label which is a requirement in 514.12.2 where it is that most get the 6 months as a requirement. This label is not required if the Guidance for recipients is included with the certification for initial verification for a domestic or similar installation and given to the person ordering the work.

Strictly speaking we should be adhering to the manufacturers recommendation for each device as this is generally the requirement of BS7671.

My Intention was not to go against accepted guidance but we all know hardly anyone tests their RCDs in domestic premises let alone every 6 months but to try and do it at least once a year.