# any Sparkies? home electric question



## Sprinta (Sep 15, 2010)

first of all a bit of background.....

the house was rewired probably 25 years ago, we have had it 23

last year I needed to add lighting in the garage and my local sparky rewired it and also upgraded our house fuse box by putting in one with a couple of RCDs in place of the wire fuse type.

several times last year the one RCD covering 4 services in the house would trip out.

all of the sockets, switches and light fittings have been tested and all show OK.

nothing went wrong for 7 or 8 months until last week, the trip kept on tripping. reset and all is OK for 10 minutes or 10 hours until it goes again. 

I have tried switching all 4 service off individually but I can't get it to trip on demand.

However last night I switched off all 4 services and tried to reset the RCD and it refused to do it even with nothing switched on :? 5 minutes later it would reset OK again.

It went off again this morning..........  

no amount of loading seems to affect it, it can trip with nearly nowt switched on to all switched on

Any thoughts? although from last nights events perhaps I've got a trigger happy RCD?


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## listerdiesel (Aug 3, 2012)

I'd be inclined to think of damp somewhere that is causing an intermittent trip.

Our cooker occasionally causes an issue when something gets spilt, but once it's dry it's OK again.

For what it costs, a replacement RCD might be the issue, but in my experience it is 99% downstream in wiring or appliances.

Peter


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## raynipper (Aug 4, 2008)

I know the feeling Sprinta.
Our house about 25 years old and electrical installation protected by fuses. But the house 'disjuncteur' or main breaker is a differential one.

This started tripping for no apparent reason last October when a couple of electric radiators had been turned on. 
I assumes it was an overload and just shed some load. Then it started tripping soon after the electric oven was turned on. 
I checked the oven and eventually 'lifted' the earth wire. It was another week before the trip went again. I 'lifted' more earths on several appliances but the trip still went maybe twice an hour or once a week.?

Still haven't got to the bottom of it but have reconnected all the earths and not tripped now for over two months.

I am (was) an electrician and can't put my finger on the problem. 

Ray.


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## camallison (Jul 15, 2009)

We had a similar problem over Christmas and, after about 7 days of on/off and checking, our american style fridge/freezer turned out to be the culprit. On the 7th day, the fridge part wouldn't pull down to the set temperature. A bit of judicious Googling for that fault, resulted in a clue. The defrost thermostat was occasionally shorting to earth. Once I had replaced that, our problems were over.

So, the upshot of our problem was an appliance going faulty intermittently.

Colin


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## Sprinta (Sep 15, 2010)

camallison said:


> We had a similar problem over Christmas and, after about 7 days of on/off and checking, our american style fridge/freezer turned out to be the culprit. On the 7th day, the fridge part wouldn't pull down to the set temperature. A bit of judicious Googling for that fault, resulted in a clue. The defrost thermostat was occasionally shorting to earth. Once I had replaced that, our problems were over.
> 
> So, the upshot of our problem was an appliance going faulty intermittently.
> 
> Colin


aha - SWMBO has reported to me recently that her fridge has occasionally been making strange buzzing noises that always stop when I get called out to listen to it - now that unit I can isolate with a plugin RCD - it's a start point.


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## teemyob (Nov 22, 2005)

Hi,

The RCD can be tetsed (I have a megga that does this)

Do you mean they replaced the fuses MCB's or re-settable?


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## andrewball1000 (Oct 16, 2009)

when I had my old fuse box replaced with a modern one I was advised that certain circuits are best kept off the RCD protected ones as they are prone to tripping. My oven, sockets and immersion are separate.


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## raynipper (Aug 4, 2008)

teemyob said:


> Hi,
> 
> The RCD can be tetsed (I have a megga that does this)
> 
> Do you mean they replaced the fuses MCB's or re-settable?


Who TM.?
My house differential trip is sealed and the companies.

Ray.


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## Gretchibald (Jul 22, 2011)

Isolate things one by one. I would first try pulling the fuse for the garage since this is what was changed, a small drip from the garage roof or excessive damp in there would trip it.,very little current leakage to earth trips modern RCDs .Then pull the fuses for other circuits ie downstairs sockets, upstairs sockets, downstaris/upstairs lights, shower, boiler etc . if it doesn't trip with one one of the fuses out you have narrowed the source problem a bit.

In my cases it was a leak on one of the lights in an outhouse and on another occasion a leak in the boiler of the range cooker. The joys of living in an old farmhouse, last week we had a burst radiator upstairs, we were away at the time, just about dried out now.


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## rocky58 (May 11, 2005)

You may have some earth leakage.RCD works on a very small current 120milliamp.Could be an appliance possibly electric cooker


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## Sprinta (Sep 15, 2010)

answering some of the questions posed..........

the new 'fuse box' has 8 circuits covered by 2 RCDs - it replaced an on/off wire fuse unit of about 1950 vintage

the garage is on the other RCD and doesn't trip - it is also protected by its own RCD fusebox

my sparky is local and sort of a relative but this has him scratching his head as well because he has tested each and every socket, switch and light bulb holder to no avail.

The cooker is gas and has only a 13A plug for the timer mechanism

The suggestion about a dodgy appliance gives me hope because we might have an intermittent fault with the fridge and I can isolate that totally by way of an RCD plug or plugging it into the garage circuit

I have hope 8)


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## philoaks (Sep 2, 2008)

A neutral - earth appliance fault would presumably exhibit the symptoms that you have (i.e. still tripping with all the mcb's switched off). If it was me I'd go the route of plugging into the garage circuit to localise the fault. If you used a plug in rcd I would guess that it would need to be more sensitive/faster acting than the rcd in the main consumer unit, otherwise you'd still be in the same boat. P.S. Happy to be corrected as I'm not a qualified electrician !!


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## Sprinta (Sep 15, 2010)

philoaks said:


> A neutral - earth appliance fault would presumably exhibit the symptoms that you have (i.e. still tripping with all the mcb's switched off). If it was me I'd go the route of plugging into the garage circuit to localise the fault. If you used a plug in rcd I would guess that it would need to be more sensitive/faster acting than the rcd in the main consumer unit, otherwise you'd still be in the same boat. P.S. Happy to be corrected as I'm not a qualified electrician !!


good point, I can run a cable to the garage RCD short term


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## camallison (Jul 15, 2009)

Sprinta said:


> camallison said:
> 
> 
> > We had a similar problem over Christmas and, after about 7 days of on/off and checking, our american style fridge/freezer turned out to be the culprit. On the 7th day, the fridge part wouldn't pull down to the set temperature. A bit of judicious Googling for that fault, resulted in a clue. The defrost thermostat was occasionally shorting to earth. Once I had replaced that, our problems were over.
> ...


It is an Amana fridge/freezer, distrbuted by Whirlpool, or rather not any more! They no longer do so but commit to the legal requirement to hold spares for at least 6 years.

Your fridge "sound" could be the clue. They are all built down to a price and are often borderline on "stable running". The replacement stat cost me £18 post free.

Colin


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## teemyob (Nov 22, 2005)

camallison said:


> Sprinta said:
> 
> 
> > camallison said:
> ...


The Amana deviation stats do not normally fail that way. It is usually the heaters that go DTE.


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## camallison (Jul 15, 2009)

teemyob said:


> camallison said:
> 
> 
> > Sprinta said:
> ...


I can assure you that this one did, which surprised me too.

Colin


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## Sprinta (Sep 15, 2010)

when I got home last night from work I was told the RCD had tripped another 4 times that day so I isolated the fridge last night by plugging it in to another circuit controlled by a different RCD and waited..........

nothing happened until I was just leaving the house this morning and it tripped out again........... I reckon it ain't the fridge :x 

maybe it's the central heating? it only started to happen with the colder weather, so that's a candidate for a switch off when I get home :?


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## spykal (May 9, 2005)

Hi Sprinta

Is it possible that you have had or have a mouse or two in the house? This sort of unfathomable tripping often turns out to be mouse, rat or squirrel damage to a cable somewhere in the house. Why do they love to eat the cable insulation? Then after doing that the trip goes out every time they scamper over the exposed cable it rarely electrocutes them....the RCD protects mice and humans :roll: 

A really good search for droppings using a powerful torch may rule this one out ( I call mine a CSI torch) ....and don't forget the attic ...thats where a squirrel nest will be.


Mike


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## raynipper (Aug 4, 2008)

Headline in Computer Active magazine.
"Hacked smart fridge sends out spam emails".

Clever these fridges, maybe just messing with the trips as well.???

Ray.


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## Sprinta (Sep 15, 2010)

well I have ruled out the fridge being the culprit..........

last night moved onto the Central Heating, I turned that off much to the other half's disgust and waited to see what happened..........

nothing happened until late this morning when I got a call to say she wanted the heating back on and btw the electrics tripped out again.

so that rules out the CH, good but where next..........

time to dismantle the airing cupboard and check the whereabouts of the wiring for the front room sockets..........



and no, no way mice in here - 2 dogs with a keen nose and hearing


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## Easyriders (May 16, 2011)

These modern systems are very sensitive, especially the earth. Our son had this problem, turned out to be a short in the oven after his partner had cleaned it using a steam cleaner. She had turned off the oven first, and it was on a separate circuit, but it still tripped the main earth even weeks later, and they had to replace it.

We had a similar problem with a socket in the garage, kept tripping the main earth. It can be very frustrating finding where the problem comes from.

I sometimes think the modern trip switch type fuse boxes are just a bit too sensitive. One of our lighting circuits trips every time a cooker hood bulb blows, and believe me, they do blow quite often!


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## Bigusdickus (Nov 6, 2012)

Unplug EVerything and switch off all lighting. If the RCD stays in plug the fridge in first then wait. If the RCD stays in while the fridge cycles on and off plug in the freezer repeat the process for all appliances including washing machine. With the electricity TURNED OFF!!!!! carefully remove all fittings and check the terminals connections are tight. Have you redecorated a room and fixed a picture to the wall near a cable drop inside the wall? (found through previous experience). Have you installed a flush light fitting? Do you use an extension lead anywhere? Sometimes an older style cooker ring or oven element can cause a trip while heating up and cooling down because the element is encased in powder, if the ring cracks the powder gets damp.
RCDs work on current imbalance; what goes in through the red should come out the black; if current goes missing it will trip out.
Hope these suggestions help you otherwise call in a sparky.
Bd..


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## rocky58 (May 11, 2005)

you need to disconnect main cables to RCD and test live to earth and neutral to earth.There should be an infinity reading with a megger on both or near on both.If they show a circuit try each indivdual circuit live and neutral.This should pinpoint which circuit.Remove all appliance which plug in.RCD detects any leakage to earth in either live or neutral.


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## richardjames (Feb 1, 2006)

If one of our table lamps bulb blows it takes out the main RCD 8O 8O


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## Patrick_Phillips (Aug 17, 2006)

Don't overlook the possibility of faulty insulation in cables between sockets/appliances. A fairly common fault is when the cable is cut a bit short so that it can pick up damp from plaster as it enters the socket box. 
It maybe worth pulling all sockets etc out of their boxes and spray some WD40 into the box (not the socket). Then reassemble. Mains off during this process, of course. RCDs are measuring the input milliamps against the return, via neutral. Any difference and it will assume loss to earth or ground and trip. What I am trying to say is that the fault doesn't have to involve the earth at all.

Patrick


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