RCD a pain!

sparkfireman

Called to my mates to do a nixer... she said the toaster kept tripping the RCD, so she replaced the toaster...

It keeps tripping...
Socket is fine...
Other appliances, kettle, blender etc works fine...
Its not a case of overloading as it was the only thing operating...
In a kitchen Ring socket....
Fuse board a mixture of MCB's and Old Fuses.... (not my work!)

Any suggestions appreciated...

Thanks guys

M cebee

nothing rings a bell with me anyway

changed toaster -it still trips-other appliances works fine in same socket


you can safely rule out overload-on an rcd:pac:

assuming new toaster is ok
i'd prob ramp test the rcd and check leakage current

IR test outgoing side of rcd at 250V between L+N( joined) to earth without disconnecting appliances-to get an idea

and do a full IR test


another option is to rcbo the kitchen ring if you need to narrow it down

Bruthal

sparkfireman wrote: »

Called to my mates to do a nixer... she said the toaster kept tripping the RCD, so she replaced the toaster...

It keeps tripping...
Socket is fine...
Other appliances, kettle, blender etc works fine...
Its not a case of overloading as it was the only thing operating...
In a kitchen Ring socket....
Fuse board a mixture of MCB's and Old Fuses.... (not my work!)

Any suggestions appreciated...

Thanks guys

As m cebee says overload wont trip an RCD by itself, plug everything in the house out and see does it reset, if not then switch off all MCB`s controlled by the RCD and see does it reset, if it does, switch them all back on, if you come to one that trips it then problem might be on that circuit.

If its a neutral earth fault then the RCD wont trip with all MCB`s on and all items plugged out, will usually trip when you plug something into the problem circuit,

If its a faulty item then this will show up when you plug each item back in, and operate the item.

How did you verify if the kettle and other appliances are all fine if the RCD keeps tripping? Did you try them in a different circuit? This info would help maybe

I switched off main power in a house before and the RCD still tripped, which would make you think the RCD was faulty but it was not the RCD at fault.

After that do the test suggested by M cebee,

2011

It could be a faulty RCD. If you don't have an RCD tester to hand plug the new toaster into a socket protected by a different RCD (such as a neighbors house) and see what happens. If it causes another RCD to trip chances are it is another faulty toaster. If it doesn't the chances are the toaster is OK, push the test button on the second RCD and see if it operates.

Bruthal

2011 wrote: »

It could be a faulty RCD. If you don't have an RCD tester to hand plug the new toaster into a socket protected by a different RCD (such as a neighbors house) and see what happens. If it causes another RCD to trip chances are it is another faulty toaster. If it doesn't the chances are the toaster is OK, push the test button on the second RCD and see if it operates.

Removing the outgoing live and neutral links from the RCD and see will it then reset might show if its faulty. A faulty RCD is a good possibility alright.

Buford T Justice

I came across something like this once before when I was replacing an old fuse board with a new consumer unit. It transpired that when some lights or other were being added into the kitchen they had no neutral for the circuit so they just tapped into the neutral from the sockets. Only turned up a problem with the new consumer unit when the RCBO was fitted, It was tripping every time the kettle was turned on, and only happened with the kettle. Might be worth considering there.

Bruthal

Fingers McGee wrote: »

I came across something like this once before when I was replacing an old fuse board with a new consumer unit. It transpired that when some lights or other were being added into the kitchen they had no neutral for the circuit so they just tapped into the neutral from the sockets. Only turned up a problem with the new consumer unit when the RCBO was fitted, It was tripping every time the kettle was turned on, and only happened with the kettle. Might be worth considering there.

I wonder how that was happening, it surely must of tripped the RCD when the added in lights were turned on, but how did the kettle now trip it?

If the lights were off then its just a neutral wire from the sockets going nowhere, assuming the lights were wired right, and if lights are turned on that itself will instantly trip RCD.
Must of been something else wrong with them lights.
Just curious.

maxamillius

came across some outside lights before that had the neutral tapped off kitchen socket,massive down pour one night and lights filled with water therefore tripping the rcd!

Bruthal

maxamillius wrote: »

came across some outside lights before that had the neutral tapped off kitchen socket,massive down pour one night and lights filled with water therefore tripping the rcd!

Again though, the light would never of worked with the neutral only taken from the socket, the live must of been from the socket also.

maxamillius

sorry robbie thats correct yes they were directly off a socket,it was actually an outdoor socket which was on the kitchen circuit!

M cebee

Fingers McGee wrote: »

I came across something like this once before when I was replacing an old fuse board with a new consumer unit. It transpired that when some lights or other were being added into the kitchen they had no neutral for the circuit so they just tapped into the neutral from the sockets. Only turned up a problem with the new consumer unit when the RCBO was fitted, It was tripping every time the kettle was turned on, and only happened with the kettle. Might be worth considering there.

it's called a 'borrowed neutral'


but those symptoms don't sound right


it shuda just tripped when light was switched on

Bruthal

M cebee wrote: »

it's called a 'borrowed neutral'


but those symptoms don't sound right


it shuda just tripped when light was switched on

Hmm i thought i just said that:eek:

M cebee

robbie7730 wrote: »

Hmm i thought i just said that:eek:

you did but i copied it

and pasted it it:D

Bruthal

M cebee wrote: »

you did but i copied it

and pasted it it:D

No harm in that, sure is`t that what i always do:)

SparKing

Had a similar problem before where there was a bit of nuisance tripping on a kitchen radial but it only seemed to trip when the toaster was used, not the kettle either, so I swapped out the toaster, assuming it was faulty, for a smaller one which seemed to be fine.
Was called back again the following week for more tripping so I ended up tearing the kitchen units apart to follow the cable and found a tiny tear on the cable which exposed the neutral copper and this because of dampness under the units seemed to be causing the tripping. Moral of the story is, follow Em Ceebees advice and megger the cable.
Also, a previous electrician had "fixed" the problem by bypassing the RCD entirely, cowboys Ted, they're a bunch of cowboys

Bruthal

SparKing wrote: »

Had a similar problem before where there was a bit of nuisance tripping on a kitchen radial but it only seemed to trip when the toaster was used, not the kettle either, so I swapped out the toaster, assuming it was faulty, for a smaller one which seemed to be fine.
Was called back again the following week for more tripping so I ended up tearing the kitchen units apart to follow the cable and found a tiny tear on the cable which exposed the neutral copper and this because of dampness under the units seemed to be causing the tripping. Moral of the story is, follow Em Ceebees advice and megger the cable.
Also, a previous electrician had "fixed" the problem by bypassing the RCD entirely, cowboys Ted, they're a bunch of cowboys

Ye could talk that into comin down ted.

M cebee

bypassing rcds:mad:

why do people do this when they can't fix it

i wouldn't call them electricians

johnnyjb

I changed an old fuse type board (no rcd) for a mcb board few years ago.

Few days later kitchen circuit was tripping rcd

An older socket was causing it, the neon light was trapped and shorted against the earth plate inside

296924.jpg

.G.

M cebee wrote: »

bypassing rcds:mad:

why do people do this when they can't fix it

i wouldn't call them electricians

They probably arent. Plenty of "handymen" do electrics.

that said I've worked with a fair few qualified lads who shouldnt be let near a pack of batteries let alone mains voltage

Bruthal

superg wrote: »

They probably arent. Plenty of "handymen" do electrics.

that said I've worked with a fair few qualified lads who shouldnt be let near a pack of batteries let alone mains voltage

Thats what big building booms do, a fella can drill a few holes and cut unistrut and thats it, he`s in demand.

sparkfireman

robbie7730 wrote: »

As m cebee says overload wont trip an RCD by itself, plug everything in the house out and see does it reset, if not then switch off all MCB`s controlled by the RCD and see does it reset, if it does, switch them all back on, if you come to one that trips it then problem might be on that circuit.

If its a neutral earth fault then the RCD wont trip with all MCB`s on and all items plugged out, will usually trip when you plug something into the problem circuit,

If its a faulty item then this will show up when you plug each item back in, and operate the item.

How did you verify if the kettle and other appliances are all fine if the RCD keeps tripping? Did you try them in a different circuit? This info would help maybe

I switched off main power in a house before and the RCD still tripped, which would make you think the RCD was faulty but it was not the RCD at fault.

After that do the test suggested by M cebee,

RCD only trips when toaster is plugged in.

Everything else runs fine....

if theres a neutral earth fault the RCD WILL trip with MCBs on!

Bruthal

sparkfireman wrote: »

RCD only trips when toaster is plugged in.

Everything else runs fine....

if theres a neutral earth fault the RCD WILL trip with MCBs on!

Not usually if there is no load on it wont. It usually wont trip if nothing is plugged in on the affected circuit with neutral earth short. On non neutralised installations its more likely alright.

Did you try the toaster plugged into a different circuit.

sparkfireman

Similiar off/on topic question.... Got a phone call just this minute and my head isnt right after an all nite house fire! :O

Jus outta bed...

But my mates immersion element keeps tripping RCD on BATH only...
His ma called an "electrician" friend of hers... who bypassed the RCD and immersion works fine on bath sink... etc....

How is this?? Is the whole tank live?

Cant think...

Someone answer

sparkfireman

robbie7730 wrote: »

Not usually if there is no load on it wont. It usually wont trip if nothing is plugged in on the affected circuit with neutral earth short. On non neutralised installations its more likely alright.

Did you try the toaster plugged into a different circuit.

toaster works fine...

Bruthal

sparkfireman wrote: »

toaster works fine...

Did you try a kettle in the same socket the toaster was tripping the RCD from, its a neutral earth fault alright by the sounds of it.

sparkfireman

robbie7730 wrote: »

Did you try a kettle in the same socket the toaster was tripping the RCD from, its a neutral earth fault alright by the sounds of it.

Kettle works in the same socket!

Bruthal

sparkfireman wrote: »

Similiar off/on topic question.... Got a phone call just this minute and my head isnt right after an all nite house fire! :O

Jus outta bed...

But my mates immersion element keeps tripping RCD on BATH only...
His ma called an "electrician" friend of hers... who bypassed the RCD and immersion works fine on bath sink... etc....

How is this?? Is the whole tank live?

Cant think...

Someone answer

The element likely has a fault to earth on it, usually that is caused by the element copper outer jacket splitting and some current flowing into the water to earth, or just a neutral earth fault somewhere within the immersion heater unit, a direct live earth fault would usually trip the MCB as well. The tank is unlikely to be live, but bypassing the RCD is nuts. Insane. Bypass and walk away,, job done??

Never ceases to amaze me the ``electricians`` that are out there

Bruthal

sparkfireman wrote: »

Kettle works in the same socket!

So the toaster trips the RCD in one socket, but does`t in a different one, and the kettle works ok in the one affected by the toaster?

sparkfireman

robbie7730 wrote: »

So the toaster trips the RCD in one socket, but does`t in a different one, and the kettle works ok in the one affected by the toaster?

Ok...

Kitchen ring socket....
toaster works in living room but not in kitchen...
all other appliances in kitchen works fine in all sockets...
toaster trips RCD in kitchen only...

Bruthal

sparkfireman wrote: »

if theres a neutral earth fault the RCD WILL trip with MCBs on!

If there is a neutral earth fault and nothing is plugged in on the circuits fed from the MCB`s then MCB`s on or off wont make a difference.

Bruthal

sparkfireman wrote: »

Ok...

Kitchen ring socket....
toaster works in living room but not in kitchen...
all other appliances in kitchen works fine in all sockets...
toaster trips RCD in kitchen only...

Did you take the socket off that the toaster is tripping in. and check it. Its a strange one