Electrics keep tripping

[bixbycanyon]

Due to the electrics in our house being old it was causing it to trip out and then it melted the RDA (i think) so another RDA was fitted. This is more sensitive so the electric trips out about once every couple of days.

We don't know whats causing it to trip as it often happens at night or early morning when nothing is on?

The problem is we're going on holiday next week and don't want to electric to trip again because we've got 2 fridge freezers full of food and it would also leak water out all over the floor.

What can we do to prevent this? There's a small extension on our house with newer electrics, would it be pointless running an extension from the new extension to plug the fridges in and unplugging all over appliances (inc turning boiler off)?

Sorry I'm clueless when it comes to electrics!

 

[EFLImpudence]

Due to the electrics in our house being old it was causing it to trip out and then it melted the RDA (i think) so another RDA was fitted. This is more sensitive so the electric trips out about once every couple of days.

Do you mean RCD (RCCB or RCBO) or MCB (miniature circuit breaker)?
I don't know why a 'more sensitive' one would be fitted unless the first was just wrong.

We don't know whats causing it to trip as it often happens at night or early morning when nothing is on?

It is most likely something which is wet or something with a heater or motor - outside light, fridge, central heating - even if off.

The problem is we're going on holiday next week and don't want to electric to trip again because we've got 2 fridge freezers full of food and it would also leak water out all over the floor.

You could use an extension lead plugged into a non RCD circuit or another RCD circuit.

 

[plugwash]

I don't know why a 'more sensitive' one would be fitted unless the first was just wrong.

It may just be luck, afaict RCD trip points have a pretty wide tolerance on them (IIIRC they are required to hold in at half rated and required to trip at rated, so the trip point can be anywhere between those values).

 

[plugwash]

You really need to determine what is connected to what. Once you've done that you can figure out if you have any sockets that are covered by a different RCD or no RCD at all.

 

[ericmark]

I am guessing a little here that the original RCD was 100ma because you have a TT system and the new one is 30ma because these protect personnel and the amount now protected by a single RCD is too much for a single 30ma unit so it's right on the edge.

The system really needs splitting so less is on a single RCD but failing that not all RCD's are the same. Reading this report on the X-Pole RCD it would seem this type is less likely to trip.

There are even super RCD's which will auto reset but at around £350 each they are not really for domestic but more for things like remote pumping stations.

As to your extension it would depend how it is fed. If fed from same RCD then no point but if from a different RCD then may be.

The rules say:-

314.1 Every installation shall be divided into circuits, as necessary, to:

(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation

From what you are saying the installation has not been divided into enough circuits likely the only way to divide into more circuits would be to change the consumer unit.

I also have an old set up with two RCD's fitted around 1992 which feeds two old consumer units with the original fuses changed to MCB's and I have found over the years we seem to get a batch of tripping then it may go for a year without tripping. In theory one trip should not affect the other but often resetting one will trip the other and I have very rarely found faulty items which cause it to trip. Last time it tripped it was a faulty item a computer power supply went down blowing the 5A fuse and causing the RCD to trip but in theory it should not have affected the RCD as it was a Class II item.

So from experience I have realised anything which causes a spike can trip the RCD plugging in a PC or unplugging a PC is a common cause.

This means the starting of the compressor of a fridge or freezer or stopping can cause the RCD to trip as can the freezer when it goes into auto de-frost mode. This is hard to monitor the only way to test is to move the fridge or freezer to a circuit fed from a different RCD where there is only one RCD this clearly is a problem.

It is permitted to have a non RCD protected supply for fridge/freezer but I would gather not enough time to install this.

Only thing is make sure your insurance covers the freezer contents.

 

[Aragorn84]

I guess what you need to figure out, is if its just "normal" earth leakage building up to the point where your just at the limit as eric suggests, or if its an actual fault.

In a similar situation we had some nuiscance tripping start after a new board was installed (by a bit of a cowboy it transpired), though it was much more sporadic than yours, eventually after lots of complaining the landlord got another spark out who discovered there was a foot of water under the house due to a high water table, and lots of shoddy junction boxes under the floor dangling in the water!

Unfortunately we cant really figure that out from the internet.

Post a photo of the "fuse board" and indicate which device trips out, which might shine some more light on the issue, and wether plugging into a different area of the house would help in any way.

 

[Taylortwocities]

We don't know whats causing it to trip as it often happens at night or early morning when nothing is on?

At teh same time, every day? I'd suspect heating/boiler components.
Outside wiring is also a major cause of this sort of thing.


Don't forget that an RCD will trip if there is a fault on teh neutral as well, so something does not have to be "running" to cause an RCD to trip.

 

[JohnW2]

Don't forget that an RCD will trip if there is a fault on teh neutral as well, so something does not have to be "running" to cause an RCD to trip.

In practice, I think it's very unlikely that an N-E fault would cause an RCD to trip unless something was 'running' - but, of course, there will nearly always be at least some 'something'! In fact, with a TN-C-S supply, I think it would actually be impossible for an RCD to trip in the absence of 'something running'.

Kind Regards, John

 

[viewer]

This could take a while to sort out as there may be a number of problems. If things are so bad that components melt then I wouldn't want to leave the house with the power on. Can you get a friend or family member to keep your frozen goods?

 

[JohnW2]

So from experience I have realised anything which causes a spike can trip the RCD plugging in a PC or unplugging a PC is a common cause. This means the starting of the compressor of a fridge or freezer or stopping can cause the RCD to trip as can the freezer when it goes into auto de-frost mode.

I'm not sure why it should only happen when the appliance went into auto-defrost mode - the compressor is going on and off all the time during normal operation. FWIW, I've had a freezer and two fridge-freezers running on their own RCBOs for years, and have never had any trips.

Only thing is make sure your insurance covers the freezer contents.

I wouldn't be confident that they would cough up if the owner admitted that they went on holiday whilst aware of the potential problem and with the freezers full of food!

As viewer has said, there could well be wider issues, and I'm not sure that going on holiday with the electricity still switched on is necessarily all that desirable.

Kind Regards, John

 

[bernardgreen]

Many freezers put the water created in frost into a metal dish fitted on the top of the compressor. When the defrost cycle ends and the compressor starts running again the heat from the compressor evaporates the water over the next few days. If the dish over flows the water can run down the side of the compressor and into the terminal box.

Reasons for overflow are, among other reasons, too much frosting, too frequent defrosting ( no time for full evaporation ) or the dish filled with peas that have gone done the defrost drain into the dish.

I think it would actually be impossible for an RCD to trip in the absence of 'something running'.

A neutral to ground fault on a TT system can trip an RCD if the neutral bounces above ground and the ground rod is low impedance. Vne = 6 volt ( Neutral above ground) and rod impedance 200 ohms will give a 30 mA current along the neutral through the RCD sense coil.

 

[JohnW2]

I think it would actually be impossible for an RCD to trip in the absence of 'something running'.

A neutral to ground fault on a TT system can trip an RCD if ....

Bernard, that's very naughty - you ought to be a politician You removed the first few words from my statement you quoted, namely "In fact, with a TN-C-S supply..."

...the neutral bounces above ground and the ground rod is low impedance. Vne = 6 volt ( Neutral above ground) and rod impedance 200 ohms will give a 30 mA current along the neutral through the RCD sense coil.

Hence my specific reference to TN-C-S I agree that with a TT (or TN-S) supply it is theoretically possible for there to be a high enough N-E potential difference for a N-E fault in the installattion to trip an RCD even if there are absolutely no loads in the installation - but that will be pretty rare.

Kind Regards, John

 

[bernardgreen]

Bernard, that's very naughty - you ought to be a politician

Not naughty. Just careless reading...... Sorry

 

[bixbycanyon]

Interesting points guys. I personally didn't want to leave the power on because of the dodgy electrics but my partner doesn't want to loose the 2 freezers full of food.

Could it be that there's wet wiring in the house causing the issue? Our bathroom was leaking water down the wall and into the socket in the kitchen.it may still be wet all inside there. I have no idea if everythingsl on one Rda.

 

[Aragorn84]

Interesting points guys. I personally didn't want to leave the power on because of the dodgy electrics but my partner doesn't want to loose the 2 freezers full of food.

Could it be that there's wet wiring in the house causing the issue? Our bathroom was leaking water down the wall and into the socket in the kitchen.it may still be wet all inside there. I have no idea if everythingsl on one Rda.

As i suggested earlier in the thread, take a photo of the consumer unit (fuse box) and post it up.