Can RCDs wear out?

[gray52]

I have a problem with the fuse tripping every time I switch on the washing machine. It started a few months ago when using the machine intermittently tripped the fuse. This got gradually worse until it happened every time.

The washing machine was old so I decided to get a new one. Initially this worked fine and then the problem re-occurred. I then ran an extension lead down from the upstairs circuit. Again this seemed to work for a while but now it is completely impossible to use the washing machine in any socket in the house...

As a complete novice when it comes to electrics I don't know what's the next course of action. An electrician tested the downstairs circuit and could find no fault. He suggested changing the fuse board but I don't want to go down this expensive route if this is not the problem. Unless it is a coincidence (with 2 faulty machines) I can't see how the appliance is at fault.

Any advice would be greatly appreciated.

Thanks,
Russell

 

[slippyr4]

Did the electrician do a Period Inspection? he'd have given you a certificate, and a sheet of test results. They would be useful. And, a well equipped spark would be able to specifically test the RCD.

Although not exactly unusual for a washing machine to leak a little to earth; it shouldn't be leaking 30mA. It's possible that other things on your circuit are leaking a little current, so that the washing machine pushes it over the edge.

Try unplugging (not just switching off) everything on the same circuit as the washer, and seeing if it then trips the RCD.

If it does not, then reconnect individual items until the RCD trips- you may be able to isolate and entirely different appliance which has a fault.

 

[gray52]

Thanks for such a quick response!

The electrician was a friend of a friend who had a quick look so there is no report. Also, unfortunately, I was out at the time so I don't really know how thorough the test was. I think I'll just have to ask him back in to have another look.

I don't think it can be another appliance causing the trip as I have tried it on 2 different circuits. On the upstairs circuit there are only a few things plugged in but I will try unplugging them to see if there is any effect..

Thanks again,
Russell

 

[Lectrician]

What type of CU?? Old one, one with an RCD as a main switch, a split load type??

Does it trip with any other significant loading introduced?

 

[gray52]

I'm a complete novice so not sure what you mean by CU Assuming it's the "fuse box" then the info on it is:

Wylex WSEM 63/2
100 mA trip
Cat no NNEM 616

Sorry for being so vague!

 

[gray52]

...oh, and no, it's only the washing machine that causes a problem. Other high load appliances such as the hoover are fine.

 

[breezer]

chances are its the washing m/c then.

post in appliances, but do say exactly when it trips

 

[gray52]

Thanks I'll try in the appliance forum

 

[ebee]

The title was can RCD`s wear out.

Those that I have seen malfunction have failed unsafe i.e failed to trip on testing. I would be happier if they failed safe,

 

[JohnD]

When you say the fuse trips, it it the RCD (about 2 inches wide, and only one of them in the CU) or the MCB (an inch wide or less, and there will be several of the same size) that trips? what other things go off when it trips? And what numbers are on the thing that trips? **this is a very important question **

You say you have a 100mA RCD, so to trip this would take a pretty big fault. Is there any sign of water or damp round the socket. e.g. if the supply or waste pipes pass close the electrical parts and might be leaking or splashing?

A Wylex RCD may look something like this

and a Wylex MCB like this

edited to say, sorry, I have looked in the appliances section, but I reckon if it's the 100mA that trips, theer's a worrying fault on one of the watery things.

 

[gray52]

Thanks for all the responses, I'm grateful for all the offers of help!

I have registered the fault with Hotpoint now as the machine is only 1 month old. If they can find no fault with the machine then I'll be back for more advice on the electrics.

 

[securespark]

You need to get a spark to do a ramp test on the rcd.

Do not carry this out from a socket outlet, rather test the rcd itself: disconnect it from the busbars and test the rcd in isolation. An rcd should never trip at 15mA or below. The minimum I would accept is 18. Most rcds I test are between 18-24, although the Wylex ones can be as high as 29mA.

If the rcd is tripping at a healthy current, then suspect an appliance.

If the rcd trips immediately before a current reading is displayed, or if it trips below 15mA, then it is goosed.

 

[JohnD]

He says rcd is "100 mA trip " so it must be quite bad.