Tripping RCD

[Jevban]

Hello
Elderly woman here, read lots of forums like this looking for advice but currently none the wiser,!
I had Led PIR lights installed recently, replacing old security lights and a decorative light at the front door using the original wiring. An electrician did the work. The lights run off my upstairs light circuit. He told me he found two wires, earth's, not connected, so connected them. That night, my RCD, central in my fusebox, supposedly not protecting the side the light circuit is on, tripped. It had rained. Since then, the RCD trips constantly. The electrician who changed the lights came out , disconnected the wires from the one light, but left the others, saying it's not his work that caused the fault and to find another spark. Another lad came, did some remedial work in the house and left. That night, the RCD tripped again. The second spark returned and worked really hard over 2 days, finding numerous faults using a multi meter and undoing all my sockets finding loose earths and broken sockets. All dealt with. 2.5 days later, last night, it rained overnight and I got up to no electricity again . He tells me that as the fault seems to be N to E, that a new CU with RCBOs will show more easily where the fault is...It rained today..I'm home, no RCD trip. I'm many hundreds of pounds down presently and looking at getting the upgraded CU but with no guarantee this will cure the problem. Sorry for the very long story, but does anyone have any ideas what may be wrong,?

 

[JohnD]

Earth leakages can be very hard to track down. It might be water related, more often than not, and cables to outdoor lights and sockets are very suspect.

It's also possible that your upstairs lights have a borrowed earth or neutral, this was sometimes done when you have two-way switching of hall and landing lights with upstairs and downstairs switches for the same lamp.

The person who spent days searching, if competent and diligent, has probably done the best he can. Old houses sometimes have a lot of alterations and extensions over the years, some of them poorly done. An experienced old hand may have seen more oddities over the years.

Post a photo of your consumer unit please, with the door open, and the wiring around and and between it, the meter and incoming supply, it may spark other ideas.

In the meantime, put a table lamp in the hall and landing, plugged into a socket, and see if the fault continues even when you do not use the hall and landing lights. Try leaving the outdoor light off. Modern LED bulbs use so little electricity that it is not worth buying a timeswitch, you can just leave the landing light on all night.

BTW I have individual RCBOs and they are very good for avoiding trips, and reducing inconvenience. They do also help to isolate where the problem is, and remove confounding errors when you have two or more intermittent faults. True, they are more expensive, but fault finding without them can cost more.

 

[Jevban]

Thank you so much for your reply...I do have two way switch for my upstairs and downstairs lights in the hall with the outside lights running off the upstairs lighting circuit. Please see picture of my CU
It's the RCD in the middle that is tripping.
Jan

 

[JohnD]

It's too fuzzy for me to read. You may need flash.

Do you really have an on-site generator in the loft? Is it solar panels?

Show the surrounding cables please.

If you ever want better labels, you can make them with

Pardon our interruption...

Pardon our interruption...

The trick is to cut it to length and stick it to a very clean worktop, write on it, then peel it off and stick it to the CU.

 

[Murdochcat]

How old is the property? The wiring?

If the rcd didn’t trip before the lights were updated, then that may give a pointer to the issues.

Problem is the older the property, the more DIY has been done and issues can run deep.

Changing the CU may help but it won’t fix the problems. My experience is that the majority of younger sparks lack the knowledge and competence to sort these issues. And it’s never cheap either

 

[Jevban]

Other wiring in the cupboard

It's too fuzzy for me to read. You may need flash.

Do you really have an on-site generator in the loft? Is it solar panels?

Show the surrounding cables please.

If you ever want better labels, you can make them with

Pardon our interruption...

Pardon our interruption...

The trick is to cut it to length and stick it to a very clean worktop, write on it, then peel it off and stick it to the CU.

Thanks John..best I can do with my phone. Sorry. I'm pretty useless. The other thing you ask about are my solar panels..the second spark says they are protected by their own RCD... install done by a very good company, all certified and no problems since 2013.
I will try to do the better marking
The second electrician said some of the wiring was not congruent with the numbering and changed some of that..

 

[Jevban]

How old is the property? The wiring?

If the rcd didn’t trip before the lights were updated, then that may give a pointer to the issues.

Problem is the older the property, the more DIY has been done and issues can run deep.

Changing the CU may help but it won’t fix the problems. My experience is that the majority of younger sparks lack the knowledge and competence to sort these issues. And it’s never cheap either

The wiring is 30 years old. Was upgraded with an extension 17 years ago when the new CU was fitted.
I agree re the problem not existing, or not making itself known before the new lights and the wires that were disconnected being connected...but the young sparks sdy this is not the issue
I agree re the younger sparks and have looked extensively for a company with 20 + years experience but most are 5 - 10 years...post qualified

 

[Jevban]

The wiring is 30 years old. Was upgraded with an extension 17 years ago when the new CU was fitted.
I agree re the problem not existing, or not making itself known before the new lights and the wires that were disconnected being connected...but the young sparks sdy this is not the issue
I agree re the younger sparks and have looked extensively for a company with 20 + years experience but most are 5 - 10 years...post qualified

Sorry
Missed the age of the house... around 100 years

 

[JohnD]

Did you search on a scheme such as NICEIC, or on an advertising site such as chequertrad?

For some reason parish magazines are a good source for established local businesses.

 

[Jevban]

Hi John, yes, spent days looking for a long qualified man who would have experience of problems such as mine in an old house..I even rang NICEIC...they weren't much help.
Not heard of chequertrad
I'll go look now
Thank you

 

[Murdochcat]

Do not use check a trade. You can’t leave bad review’s which means nobody really knows if they can trust them.

Ask friends and neighbours for recommendations

 

[JohnD]

Checker is not a good source.

 

[ericmark]

We have three tools to help us, one the RCD tester it is to be far not that common to find a faulty RCD, and I don't really trust the testers, so I would swap RCD if could not find fault. The next in or arsenal is the installation tester, these use 500 volt to find faults, and is the main tool for finding faults like you are reporting, but these do have a small problem, they test with DC, so leakage due to long cable runs and inductive or capacitive linking can be missed, so we also have the camp on ammeter this does show the total leakage, but will not work once the power has tripped.

finding numerous faults using a multi meter

If only using a multi meter, no wonder faults not found.

He tells me that as the fault seems to be N to E, that a new CU with RCBOs will show more easily where the fault is...

That is true, my thought would be however, if I can't find fault, fully disconnect outside lights for a week and see if still a fault, or at least fit a two pole switch so you can isolate them, yes I will admit my outside lights are only switched, not isolated, but my RCBO's are not tripping. Seems so easy to fit two pole switch can't under stand why no all ready been done.

I will admit not easy to find an intermittent fault, daughter house found socket fixing screw touching a neutral which had been poorly stripped, and first to admit it took some finding.

The RCD should not trip at ½ rated value, but must trip at rated valve, and back ground leakage should not exceed 30%, also we are only allowed up to 3.5 mA per circuit without special earthing arrangements, so the clamp on shown is showing 8 mA for whole house, if using a single 30 mA trip would be allowed 9 mA, opening up the CU I would not expect any circuit to exceed 3.5 mA however for many years my clamp on, would only measure 10 mA on the first increment, what I hoped was if it did not trip at 15 mA the tester used, to test the ½ rated value, then likely less than 10 mA leakage, in real terms I was crossing my fingers. I do wonder how many electricians cross their fingers like I did?

But in the main they will have the insulation tester, and a reading of over 1 MΩ at 500 volt normally means there will not be a problem. The first meter is expensive over £100, the second two, I paid £35 each for them, the fourth I bought in Hong Kong for around HK$ 150 so around £12 before the Chinese take over.

One would hope when it's ones business one would have something like this,

which is not what we would call a multi meter, although technically I suppose it is, but without the tools unlikely to find the fault.

 

[Jevban]

Hi and thanks. No clamp on meter used but the multi meter looks a bit like your last picture and he told me it cost upwards of a thousand pounds. Just utterly stressed about being unable to fully isolate it as to be fair, was this ast man who worked solidly and to my untrained eye, methodically, doing something, then testing...doing another thing, then testing.
I'll ask about the switch for the lights. Thank you.

 

[Murdochcat]

If you've paid for investigations and testing what did the invoice(s) say?

I always list what I've done and note on the invoice things that are relevant