HELP! Why keep tripping?

[gazandlucy]

Just moved in to a new house with an updated fusebox rcd etc.. The Upstairs lights kept blowing when on and tripping the MCB every now and then so fitted some new low energy ones. Now the whole house electrics trip every 2 or 3 days even if they are not on?!?

I did notice when fitting the new ceiling rose that even though the mcb was off that if the bare wires touched the RCB tripped.

So why does it only trip every 2 or 3 days even if there is no lights on??

I work offshore and it is driving my family CRAZY!

Thanks.

 

[plugwash]

shorting neutral to earth will usually trip a RCD even if the MCB is off.

I would suggest you start by making a through inspection of the lighting circuit, especially any parts of it you messed with.

 

[gazandlucy]

The lights all work fine for days. Everything is wired correctly.
Could it be that the house alarm may be powered by the lighting circuit so when the MCB is turned off there is still residual power from the alarms back up battery?

Still doesnt explain why everything is good for days?

 

[JohnD]

Is the thing that trips an MCB or an RCD?

can you post a picture of it?

 

[gazandlucy]

Hi

The MCB used to trip when i had small candle type bulbs ( 6 in total )
But since fitting new roses and energy bulbs the rcd trips the whole electrics?

I am offshore so cannt check but i couldnt understand why originally when the bare wires touched (with the MCB switched off) it tripped the RCD?
So there must be current flowing some where. I have had an alarm fitted in last 3 months and if it is powered by the light ciruit, (and the MCB is off) would the flow from the battery cause it?

All the connections are perfect as i have rewired before.
Thanks

 

[ColJack]

you say the conections are perfect yet you use the term "bare wires" repeatedly...

exactly which bare wires are you talking about..?
and there should be NO bare wires at all in any case..
even the unsheathed copper earth wires from twin and earth wiring should have earth sleeving applied to them prior to termination..

lighting circuits should not be on an RCD or even on the RCD side of a split load board..

do you have any outside lighting?

water ingress to these sometimes causes tripping..

even with no load connected, some RCD's will trip if you touch earth and neutral together since there is a small current circulating inside the RCD itself to monitor these things.. ( these usually have an earth lead from the RCD )

 

[gazandlucy]

no what i mean is the bare ends of the wires prior to attaching to the new rose.

All have plastic sheathing!

What i dont understand is why a period as long as 3 days passes before the RCD trips.

The RCD is on the far end of the fuse box with all the MCBs on the other side.

And why would it affect the MCB initially but now trips the RCD when all i have done is fitted 3 new roses (perfectly)?

I do appriecieate all your help

 

[ColJack]

low energy bulbs tend to be "leaky" down to earth as do many computer power supplies and so on..

something like the alarm doing a charge cycle every few days may well be doing the tripping by taking the acumulated earth leak over the 30mA threashold..

or it might just be damp in an outside light on cold nights, or rain getting in or any number of reasons..

there seems to be some underlying fault somewhere since the MCB used to trip..

unless you have all the kit to do a test, get the place tested and inspected ( you can get these done for free some places.. the local companies touting for work.. )
this should flag up any serious faults with the wiring etc..

 

[Space cat]

To answer one of your puzzles you need to understand what an RCD does. It compares the current flowing out through live and back through neutral and looks for any mismatch. In a perfect circuit, what goes out must come back and so they will match exactly.

If current that goes out through the live wire leaks to earth it will not come back through the neutral wire. The RCD detects this and trips if it's too big. Such leakages are common in heating elements whose internal insulation has degraded. Also in toasters with large burnt crumbs wedged between the element and the case.

In your case the MCB was off so there was no live current in that circuit but ---

If neutral and earth wires are touching ANYWHERE in an RCD protected circuit, the returning current has two possible routes. Some of it will choose the earth wire and so there will be a shortfall of current going back through neutral. The RCD will trip. Does that make sense?

To get back to the actual problem:

1) Did the MCB trip at random when you had those candle bulbs or only when a bulb blew? It's quite common for blowing filament bulbs to trip MCBs.

2) Which circuits are actually on the RCD? To put it another way, what goes off when you deliberately trip the RCD with the test button?

3) If the alarm is on the RCD, did the nuisance RCD tripping start after you had it fitted?

 

[gazandlucy]

Thanks for that information.

The RCD trips the whole electrics in the house.
The alarm was fitted shortly after moving in so i am not sure if it used to trip before it was fitted.
Only the MCB tripped before changing to low energy bulbs.

I have no outside lights and it is strange how the RCD trips every 2-3 days at around 11am?

Thanks again for taking the time to anwser!

 

[Lectrician]

Stop with the lights - I think you sorted that problem, the MCB no longer trips.

The RCD protects your whole house.......so stop accusing the lights!

Could be anything at all in your house. Could be an appliance, could be the fixed wiring.

I would get a spark in who knows how to fault find using an insulation tester.

 

[Space cat]

the RCD trips every 2-3 days at around 11am?

Is this the only time it trips? Think carefully. What happens at 11 am because Lectrician is right; it could be anything in the house.

Does somebody have a bath - and then use a hair dryer? Does an immersion heater come on? Make a point of not switching on anything at this time and see if it still trips. Your electric meter will tell you whether there's anything on that you don't know about.

 

[gazandlucy]

Only assuming its the lights as these are what started the whole episode! Presumed that there must be more reisitance in the new energy bulbs that cause the RCD to trip instead of the MCB.

I use appliances every day ie washer iron dryer etc.. so cannt understand why every 2 days.

I am thankful for all your replies and i suppose i will have to bite the bullet and get a sparky in.

Any recommendations for the Chester/Liverpool area?

 

[sparkydude]

have you changed the fittings so they will not take a normal lamp? if not why not try removing the low energy lamps and installing normal lamps again and see what happens.

Nick

 

[gazandlucy]

Just your average bayonnet ceiling rose?