RCCB tripping randomly

[Wah007]

Hello Experts, I was wondering if I could get some help on a strange issue I have with my electrics,

For the last 2 months my RCCB switch on the consumer unit has been tripping. Sometimes it trips a few times in one day and sometimes it will go 10 or 20 days without tripping. I can check this as my internet router has an uptime where it resets to zero when the electricity turns off.

My next door house has just been sold and the new owner is having the house refurbished (new walls, floor, ceiling etc). I've noticed that when the builders use their power tools next door that's when our RCCB trips. It doesn't happen every time they use them which is odd. Their's doesn't trip as I can hear their tools still running.

Most of the time our light bulbs dim for a split second when they start to use their power tools.

My consumer unit is a Crabtree Starbreaker and it's 11 years old.

Any ideas?

Thanks

 

[paulcopeman]

power tools inherintly pull a large current and an especially large one on start up due to motors and transformers that are in use so this may be the cause of your lights dimming for a short time when they are using them.

as for the rccb tripping, it could be a faulty rccb I suppose but its only going to get rectified by testing all circuits affected properly. an experienced electrician with a proper test kit can find faults on wiring that cannot be detected without the correct equipment. it may take a little time to locate the fault, but in my experience it can usually be rectified quite quicky once the faulty piece of cable has been located.

 

[SPECIAL LOCATION]

Loads of ideas.....

But in order to eliminate the various options out of the equation you need someone with proper electrical test equipment...

For starters you will need to verify the supply earthing arrangements and that the external earth loop impedance is OK.

(or if its a TT earth arrangement you will need to verify Ra)

You will also need to check the RCCB is operating correctly within its  correct tolerances..

e.g. make sure its is not over sensitive.  This needs an RCD tester

Then you will need to check you have no circuits with low insulation resistance....   This needs an insulation resistance tester

Then check you have no dodgy appliances connected..

once you've verified all those are OK you can start seeing if any external factors could be affecting your installation...

This time of year loads of external Christmas lights in boxes that aren't quite as weatherproof as you though can introduce problems..

Or..

more bodies in a house using more appliances can highlight defects in wiring systems..  (damaged cable, bad/lose joints etc..)

 Or

as the weather gets colder.. more furry rodent friends like coming inside our warm houses and chewing on those electric cables tucked under floors and in lofts etc..

So..  in a nutshell...

it could be one of or multiple combination of several factors..

You need some proper test equipment to start eliminating things out of the equation..

Which 99% of the time means a competent qualified electrician and his calibrated test gear.

Guinness  

 

[Wah007]

Thank you for the advice Paulcopeman and SPECIAL LOCATION.

I had an electrician come to check the problem today and he didn't test anything. He unscrewed the consumer unit box cover and looked at the wiring.

He said that there are two wires going into each breaker and this puts too much load on them, he said there should only be one wire in each breaker. He said he will add three extra breakers to lower the load and replace the RCCB with an RCD.

When I mentioned that this only started to happen when the builders started their work with power tools next door two months ago he said the sensitivity of the RCCB can cause it to keep tripping as quality of it goes bad over time (it hasn't let us down for 11 years).

I would have thought at least some basic test would have been done.

 

[Andy™]

:slap

sounds like you had the same sparky as in another thread, although this time he's found his screwdriver to remove the cover

also an RCCB and RCD are the same thing

adding more MCB's will not lower the load. if each circuit was overloaded then the MCB would be tripping not the RCD. and you can have as many* wires per MCB as you want. if you have a ring then there will be a minimum of 2

* i say as many as you want, start adding too many and they wont fit properly or securely, but 3-4 is often seen and not an issue

 

[Doc Hudson]

Thank you for the advice Paulcopeman and SPECIAL LOCATION.

I had an electrician come to check the problem today and he didn't test anything. He unscrewed the consumer unit box cover and looked at the wiring.

He said that there are two wires going into each breaker and this puts too much load on them, he said there should only be one wire in each breaker. He said he will add three extra breakers to lower the load and replace the RCCB with an RCD.

When I mentioned that this only started to happen when the builders started their work with power tools next door two months ago he said the sensitivity of the RCCB can cause it to keep tripping as quality of it goes bad over time (it hasn't let us down for 11 years).

I would have thought at least some basic test would have been done.

I do hope you didn't pay anything for this lack of basic testing, from the description you have given I would think it is an over generous exaggeration to call this other person an electrician.

Doc H. 

 

[Wah007]

:slap

sounds like you had the same sparky as in another thread, although this time he's found his screwdriver to remove the cover

also an RCCB and RCD are the same thing

adding more MCB's will not lower the load. if each circuit was overloaded then the MCB would be tripping not the RCD. and you can have as many* wires per MCB as you want. if you have a ring then there will be a minimum of 2

* i say as many as you want, start adding too many and they wont fit properly or securely, but 3-4 is often seen and not an issue

Lol, it probably is the same one.

Yeah, I've been reading a lot about it on here and I'm getting an idea of how these things work, even though I don't have much of a clue about my house electrics.

So the only point in changing the RCCB would be if it's too sensitive and needs replacing anyway? But he should have tested it anyway.

Thanks

I do hope you didn't pay anything for this lack of basic testing, from the description you have given I would think it is an over generous exaggeration to call this other person an electrician.

Doc H. 

I didn't pay him anything. I spoke to another electrician on the phone and he said that I should leave it until the builders finish their job next door and leave and then I should see if it still trips. Which obviously is not the solution because it shouldn't be doing it in the first place.

If anyone knows a decent electrician in the Manchester area please let me know.

 

[Sharpend]

Steps you about :innocent  

 

[Andy™]

@steptoe  is in manchester

 

[steptoe]

Was it your house I was at today, perchance,?

A builder had done the electrics and suddenly just as he is finishing the job the RCD keeps tripping for  no reason 

A pic of just one of the many things I found, I'm back tomorrow ,

 

[Evans Electric]

I think you've identified , possibly,  as the builders equipment .   Even though they are not plugged into your house ,  those bloomin' great transformers they have , plus some of the disc cutters have a high start up inrush  which could affect a nearby supply I suppose .    Next door may still have  a fuse wire board . 

Wait till they've finished .

 

[SPECIAL LOCATION]

Right...

an RCD measures the amount of electricity flowing into and out of the circuit (or load) it is protecting....

Just as with water into and out of a hosepipe,  it should be equal...

If some electricity is leaking (e.g. someone having an electrical shock) less current will be flowing back through the RCD...

In the event of a leakage current being detected it MUST trip within a specified time. 

An RCD test meter will produce a simulated fault and measure how long it takes for the RCD to operate..

and it can also measure the amount of current needed to trip the RCD..

The amount of current is in Milliamps..

because if you were getting an electric shock much more current and you would be dead anyway before the RCD operated.

Very small amounts of current less than an amp will trip the RCD, around 6.5 to 7watts is enough to give a 30ma trip current..

(Your typical lighting circuit can take 5 or 6 amps so RCD's will trip with far far less than even your lights are taking) 

All this can be tested in less than 10 minutes with a competent person and an RCD test meter..

Most of the comments that your "electrician" said.. are waffle and tosh, trying to flannel you and hide the fact that he/she actually knows jack-all about fault finding!

RCD's are designed to carry large loads, but detect small leakage currents...

Some RCD's can carry the total load of the whole property (e.g. 100Amps)  so for him to suggest too much load is almost certainly the words of an idiot!

:C

:shakehead

 

[Geoff1946]

I agree with everything that SL, and the other posters, say, but I'm struggling to visualise any mechanism that can cause a next door switching surge, or even a fault, to trip the RCD.  The only time I ever saw that was down to a very old voltage operated earth monitor, ie one where the buildings earth conductor goes through a trip coil. In that instance backfeeding of fault currents via the plumbing was causing exactly the fault described. 

Any other explanation requires SOME sort of connection between the two houses.

 

[Andy™]

but I'm struggling to visualise any mechanism that can cause a next door switching surge, or even a fault, to trip the RCD.

since there wont be any imbalance inside the property with the RCD, it shouldnt be able to. but stranger things have happened

 

[Sidewinder]

OK, apart from the excellent advice already given, an RCD can be susceptable to an upstream fault causing "nuisance" tripping, it shouldn't, but it can.

Now if, the both properties have closely linked earthing and supplies then there can be interaction between the two properties.

This can happen if they are both TT, or one TT & one TN.

If, the house is being refurbished, have the "builders" removed the means of earthing from the property?

You could do with a competent electrician with some test gear there to look at the fault.

If the builders are working, it shouldn't take long to identify the issue, and, the electrician could go and have a quick word with the builders too.

 

[Wah007]

@steptoe no that isn't my house, I'd never let a builder mess with my electrics lol. That's definitely not something I would want to cheap out on.

Thanks everyone for the advice. I've got another electrician coming tomorrow so I'll see if he can take a better look at it. If it doesn't work out I'll ask Steptoe if he would be able to take a look at it for me.      

I did speak to the owner of next door's property and he said that's weird he'll get his electrics checked out as well.          

                                                     Thanks again, I've found everyones posts really helpful and I'll be sure to mention a lot of this stuff to the guy who comes tomorrow.

 

[steptoe]

Hope you get it sorted @Wah007

What area are you,? Out of interest,,, 

 

[Wah007]

Thank you Steptoe.

I'm in Chorlton-cum-Hardy.

 

[Murdoch]

At the very least the next sparky should test the RCD'S to see how they are and also clamp the tails to see what the back ground leakage is........ Then depending on those results do some individual circuit tests......

 

[kerching]

Here's a thought

have the builders been working over Xmas?

has it tripped over Xmas?

just wondering