A few months ago we found each time we turned off the socket that feeds our TV at the wall the RCD in the consumer unit tripped off. This was the big one at the end not the individual switch that is on each circuit. I assumed a problem with the socket and was going to replace it, but in the mean time just stopped turning off at night. Last week my wife tried to make some toast and the RCD went off again and each time she tried to use the toaster it did it again so I assumed the toaster was knackered and bought a new one. We plugged in the new toaster which worked fine right up until it popped up and that tripped the RCD as well ( so I now have two toasters!) Could it be that the RCD in the consumer unit is faulty and is over sensitive? and are these replaceable or will it need a whole new unit (this one was only fitted about 6 years ago when house was extended).
RCD keeps tripping off
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It could be faulty - more likely to be a fault on the wiring though, or another appliance.
Time to call an electrician.....
Time to call an electrician.....
Yes you can change the RCD without changing the CU. It has to be the same make as the unit. BUT this is something that I would recommend to take b-a-s's advice on, call an electrician, this is not only a matter of changing the RCD, the circuit might be faulty and need to be properly tested.
If it's an RCD main switch, then if you don't have a separate isolator you also need to be able to isolate the supply to change it, so would need to call the DNO in etc etc - far easier to get an electrician in, especially since he/she should have an RCD tester, so can test it to determine if it's faulty first...
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thanks guy's.. I may have to call in a pro in the end but was hoping to try a bit of DIY diagnosis first.
The TV switch is on a much older circuit (20yrs) than the Toaster one which was part of an extention that went on 6 -7 years ago and has it's own seperate connection to the consumer unit. I've read that an earth leakage on a circuit or appliance could be the cause and when turning off the switch (or the toaster turning itself off) the extra bit of leakage is enough to set off the trip. Does that sound right and is that something I can check for? I have a normal volt/ohm/ continuity type meter that I use when testing central heating circuits or does it have to be one of those mega testers (I remember the guy checking the extention with one of those when it was finished)
Is it quite rare for the RCD to become over sensitive?
The TV switch is on a much older circuit (20yrs) than the Toaster one which was part of an extention that went on 6 -7 years ago and has it's own seperate connection to the consumer unit. I've read that an earth leakage on a circuit or appliance could be the cause and when turning off the switch (or the toaster turning itself off) the extra bit of leakage is enough to set off the trip. Does that sound right and is that something I can check for? I have a normal volt/ohm/ continuity type meter that I use when testing central heating circuits or does it have to be one of those mega testers (I remember the guy checking the extention with one of those when it was finished)
Is it quite rare for the RCD to become over sensitive?
Do not kill the messenger! normally the RCD type units are quiet reliable, they can get faulty, but I will check around. Yes the RCD protects against earth fault (leak). I do not think that a standard meter is good enough, the RCD needs RCD tester, because it needs to check the RCD for different values.
"Is it quite rare for the RCD to become over sensitive?"
yes, it is much more common if you have a lot of old circuits, for minor faults to develop on several of them which, when added together, under various conditions cause the main RCD to trip.
the most common fault on an old RCD, especially if it has not regularly been tested, is for it to stick and to fail to trip at all. Sometimes they trip and will not re-latch even when dead.
You cannot effectively test an RCD with an ordinary multimeter, since the tests include a measure of trip time under a variety of conditions. If you are an electronics engineer I suppose you could cobble together a kitbox containing various resistances to simulate fault conditions and see which cause a trip, but this would not be the entire set of tests.
please tell us the rating numbers on the RCD, and, if you can, post some pics of the Consumer Unit, RCD, meter, suppliers fuse, and the various wires between them all, especially any green and yellow ones. This will give us more of an idea what we are talking about.
yes, it is much more common if you have a lot of old circuits, for minor faults to develop on several of them which, when added together, under various conditions cause the main RCD to trip.
the most common fault on an old RCD, especially if it has not regularly been tested, is for it to stick and to fail to trip at all. Sometimes they trip and will not re-latch even when dead.
You cannot effectively test an RCD with an ordinary multimeter, since the tests include a measure of trip time under a variety of conditions. If you are an electronics engineer I suppose you could cobble together a kitbox containing various resistances to simulate fault conditions and see which cause a trip, but this would not be the entire set of tests.
please tell us the rating numbers on the RCD, and, if you can, post some pics of the Consumer Unit, RCD, meter, suppliers fuse, and the various wires between them all, especially any green and yellow ones. This will give us more of an idea what we are talking about.
The CU says.. Volex on the front and having done a quick google looks a lot (if not exactly) like this one.. the RCD is at the right hand end.
http://www.screwfix.com/app/sfd/cat...HZPCFFA?productId=82204&imageNo=null&ts=71158
although I,m sure it cost quite a bit more than £34 when it was fitted.
I could take a photo but there isn't much more to see except a bunch of about 12 wires that come down the wall into the top of it (one is a very thick earth cable) and two huge cables (are they called tails?) that come out the bottom and go through the wall to the meter box with another big earth and one more big earth that goes through to the gas meter.
Sorry I might have not been clear about testing ...I was thinking more about testing the circuits and appliances , I guessed it would be a piece of specialist kit to check the RCD.
Cheers again
http://www.screwfix.com/app/sfd/cat...HZPCFFA?productId=82204&imageNo=null&ts=71158
although I,m sure it cost quite a bit more than £34 when it was fitted.
I could take a photo but there isn't much more to see except a bunch of about 12 wires that come down the wall into the top of it (one is a very thick earth cable) and two huge cables (are they called tails?) that come out the bottom and go through the wall to the meter box with another big earth and one more big earth that goes through to the gas meter.
Sorry I might have not been clear about testing ...I was thinking more about testing the circuits and appliances , I guessed it would be a piece of specialist kit to check the RCD.
Cheers again
Don't forget the storage 'scope to record the timing...
i would be more inclined to believe it`s a wiring fault
get your self a socket tester they`re reasonable priced £7 upwards
you plug it into the socket flick the switch and it can identify several faults if any.
handy thing to have for the price and might identify the problem saving on the sparky
my money`s on a faulty earth!!!
get your self a socket tester they`re reasonable priced £7 upwards
you plug it into the socket flick the switch and it can identify several faults if any.
handy thing to have for the price and might identify the problem saving on the sparky
my money`s on a faulty earth!!!
Thanks for the socket tester suggestion that sounds like a good idea. Will a basic one detect an earth leakage ? I had a quick look around and as you say there are some for as little as £7 and some (fluke sm300 for example) about £30. All tools I buy are tax deductable so if it's worth the extra I'd be happy to pay it as it sounds like a good piece of kit to have anyway.
Cheers
Cheers
http://www.screwfix.com/prods/76975/Hand-Tools/Detection-Equipment/CED-Plug-in-Socket-Tester
this is the one i own and it detects:-
-CORRECT
-NO EARTH
-LIVE & NEUTRAL REVERSE
-NO NEUTRAL
-LIVE & EARTH REVERSE
-LIVE FAULT
by using a combination of 3 LED`s this is just a basic tester but it has pointed me in the right direction several times and saves time by not having to remove socket face plates and possibly disrupting the circuits further i`d give it 10/10 for value
the more expensive versions use audio as well as lights to identify faults
http://www.screwfix.com/search.do;j...2CSTHZPCFEY?_dyncharset=UTF-8&fh_search=45558
this one is £15 and will detect 14 wiring conditions and has a audible tone made by kewtech a brand i trust as i have some of there tools including voltage sticks a great product for finding breaks in circuits or as i found in a loft space a rat had chewed part of the way through a cable poor rat!
hope this is some help to you and let me know what you decide and if you find the fault
this is the one i own and it detects:-
-CORRECT
-NO EARTH
-LIVE & NEUTRAL REVERSE
-NO NEUTRAL
-LIVE & EARTH REVERSE
-LIVE FAULT
by using a combination of 3 LED`s this is just a basic tester but it has pointed me in the right direction several times and saves time by not having to remove socket face plates and possibly disrupting the circuits further i`d give it 10/10 for value
the more expensive versions use audio as well as lights to identify faults
http://www.screwfix.com/search.do;j...2CSTHZPCFEY?_dyncharset=UTF-8&fh_search=45558
this one is £15 and will detect 14 wiring conditions and has a audible tone made by kewtech a brand i trust as i have some of there tools including voltage sticks a great product for finding breaks in circuits or as i found in a loft space a rat had chewed part of the way through a cable poor rat!
hope this is some help to you and let me know what you decide and if you find the fault
If one of those testers does not find a fault do not take that as any sort of proof that there isn't one....
I wouldn’t waste money on a socket tester, a cheap mulitmeter is as cheap or cheaper, and although it wont tell you as much as an electricians meter for insulation tests etc, it will be more useful than the socket tester if you know how to use it. I suspect an Neutral-earth fault somewhere (but it could be other things). With a multimeter you can turn the CU off then measure the N-E resistance to try and confirm this (if the fault is apparent enough to be picked up on a normal meter). That’s where I’d start anyway.
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