Can RCD's be faulty

Hi all i'm a newbie here.

Tonight TV and computer went off,all lights ok. Checked dist board and found RCD main switch off so tried to resett it, no joy so went round unplugging things and trying RCD each time again no joy. I have two RCD's on my board and found that one is ok but the other one trips immediately I switch it on.

I thought that something on that circuit was faulty so with the aid of an extension lead connected to the other RCD circuit I tried everything that was connected to the circuit that tripped and it works fine. I also disconnected everything on the tripped circuit and RCD still trips immediately. Can RCD's go down and should I go and buy a replacement if so can I replace it myself.

This fault has never happened before and no one was doing anything just watching the TV.

Hope someone can help me please.

Regards

Tony

Yes they can go faulty. I would suggest you turn off all the MCB's protected by the RCD and try re-setting it. If it re-sets with them all of turn them on, 1 at a time, until it trips. You have then localised the circuit.

Try this before rushing out to replace anything.

Oh, welcome

if you do need to replace it, i would get an electrician in to do it, as we need to carry out a series of tests and fill out certification papers.

if you do need to replace it, i would get an electrician in to do it, as we need to carry out a series of tests and fill out certification papers.

Click to expand...

No paperwork if like for like *runs and hides*

I think it's less likely that the RCD has spontaneously failed versus some other fault. IMO

Hi all i'm a newbie here.Tonight TV and computer went off,all lights ok. Checked dist board and found RCD main switch off so tried to resett it, no joy so went round unplugging things and trying RCD each time again no joy. I have two RCD's on my board and found that one is ok but the other one trips immediately I switch it on.

I thought that something on that circuit was faulty so with the aid of an extension lead connected to the other RCD circuit I tried everything that was connected to the circuit that tripped and it works fine. I also disconnected everything on the tripped circuit and RCD still trips immediately. Can RCD's go down and should I go and buy a replacement if so can I replace it myself.

This fault has never happened before and no one was doing anything just watching the TV.

Hope someone can help me please.

Regards

Tony

Click to expand...

the RCD is most likely tripping for a reason. if everything is unplugged, then its probably a wiring fault somewhere. replacing the RCD may do absolutely nothing.

since you have to ask this, i would assume that you have little electrical knowledge or any equipment to find the fault, so it would be best calling someone who does.

No paperwork if like for like *runs and hides*I think it's less likely that the RCD has spontaneously failed versus some other fault. IMO

Click to expand...

you would still need to test RCD trip times

[quote name='Andy

Hello AFB1, welcome to the forum. as well as the checks Apache mentioned, there are also some specific operating time tests that Matt and Andy highlighted. But these need a specialist bit of test gear. How old is the fuse box?

Doc H.

No paperwork if like for like *runs and hides*I think it's less likely that the RCD has spontaneously failed versus some other fault. IMO

Click to expand...

But can a fusebox and its internal bits be called like for like?

Doc H.

But can a fusebox and its internal bits be called like for like?Doc H.

Click to expand...

id say yes, if its replacing a failed part with the same.

But can a fusebox and its internal bits be called like for like?Doc H.

Click to expand...

If we are talking about replacing a faulty RCD for a working replacement then I can't see it would be anything other than like-for-like?

Obviously a full CU change would be very different affair!

Do you disagree, Doc?

surely as long as your talking about the same BS number and rating then its like for like. i've never understood the need to test when a board is changed if your not changing the type of protection, going from 3036's to 60898's i can see a point as they have different requirements but if you already know it meets the requirements then why test again?

anyway, get a sparky in mate as you could end up looking like Don King

when you say you have removed everything what exactly do you mean? simply turning off the switch of a socket isn't always good enough as not all sockets have double pole switching so physically pulling out every single plug is the only way to eliminate a neutral earth fault. how about spurs, are all these turned off? anything outside? all these questions need to be addressed before moving ahead, atleas i would if i was fixing the problem. even then i would be doing some insulation tests before replacing something expensive like an RCD.

first thing i would be doing is testing RCD in complete isolation... if it trips, replace. if it doesnt, fault elsewhere

Hi all and thank you.

I can't see a mnfctrs name on my board but it has two ring main circuits on RCD part with a green strip under it. The two lighting circuits have a red strip under it and it says not protected by RCD.

Do RCD's just plug in to the board in other words do you just pull one out and push a new one in. I think I would like to try replacing it first before calling in an electrician as I think I might be struggling this week to find one.

I removed all the plugs and pulled fuses on the spurs the box is 3 years old. What makes me think it's faulty is that everything works on the other RCD circuit as I said earlier I connected everything from the tripping circuit via an extention lead to the good circuit and everything worked.

If we are talking about replacing a faulty RCD for a working replacement then I can't see it would be anything other than like-for-like?Obviously a full CU change would be very different affair!

Do you disagree, Doc?

Click to expand...

I don't know? I only posted to welcome Tony (AFB1) to the forum and sort of got drawn into the conversation. I shall step back and leave it to you gents to discuss properly.

Doc H.

depends on the board, but since you say you have 2 RCD's, and your description is of a single split with 1 isolator & one RCD, i doubt you are competent to work in a consumer unit which you probably cant fully isolate (and do you have equipment to check that what your working on really is dead - and dont say 'i have a neon screwdriver').for your sake, call a sparky before you kill yourself or your family.

TBH, your wasting your time replacing it anyway. apart from it going to cost around

with RCD you need to disconnect the incoming and out-going live's and neutrals.remove it from the din rail and then you can take the whole `RCD out.... it is not just a plug....

get a spark to do it....

Hello again Tony, We do have a very strong principle on this forum not to just tell people they lack experience and to encourage asking questions and doing tasks that are safe for competent DIY work.

But I do think Andy and Matt are probably right about replacing the RCD in this fuse box where you don't know what make it is, or the rating, or how it fixes to the internal wiring connections. And If you do replace it you still need the tester to check that the new one is operating correctly. That is assuming it is not a wiring fault as highlighted by Bengie.

An RCD is an item with mechanical moving parts which can fail as all mechanical devices can, but it could also be operating correctly at the moment disconnecting a faulty circuit? If the switching off circuits described by Apache doesn't work I am inclined to agree with the advice of Andy, Matt, Bengie and suggest you probably need the services, knowledge and test equipment of a qualified electrician.

It could be unwise for any forum member to suggest you go ahead replacing items unless you are competent working inside fuseboxes and have access to approved RCD tester. Are you an training electrician or just an interested DIY'er? Have you looked at our directory? we may have a member local to you who could help?

(Apache please link the directory)

Doc H.

(Apache please link the directory)

Click to expand...

Yes Sir,

http://www.talk.electricianforum.co.uk/showthread.php?t=2370

I removed all the plugs and pulled fuses on the spurs the box is 3 years old. What makes me think it's faulty is that everything works on the other RCD circuit as I said earlier I connected everything from the tripping circuit via an extention lead to the good circuit and everything worked.

Click to expand...

All this has doe id proved it isn;t a faulty appliance. It is now either a wiring fault or faulty RCD. I've never replaced a faulty RCD, I've been called out to many wiring faults.

I think you are wsting your money changing the RCD, and (no offence intended) I don;t think you should be changing the RCD yourself as it's not just a case of plugging it in. I'm not saying you are incompetent, just that I'm here, you're there, erring on the side of caution here.