More RCD issues

[GForrow]

This could take a while, bear with me.

A couple of years ago I posted about tripping of my RCD, well I’ve spent the last 2 years trying to narrow it down, but need some more help.

It’s a split load board, with only lights on the non-RCD side.

I have turned off the garage MCB, still trips, turned off the cooker MCB still trips.

Had it tested by an electrician under the house warranty, it’s the PC. Well on my 2 week holiday just finished, I unplugged all the PC equipment, and guess what. The people who checked the house tell me – it tripped.

I noticed that with the washing machine and dishwasher on at the weekend, it tripped. So I have unplugged the washing machine, and it hasn’t tripped. Today washing machine and dishwasher on again, it tripped. However yesterday the washing machine was on by itself, no trip, although at the weekend, it did.

I have no sockets in the house at all, not on the RCD protected side, otherwise I would check appliances by plugging in elsewhere. I have also observed a bulb blowing tripping the RCD, although only a couple of times.

It seems from the testing that has been done that there is a build-up in earth leakage to the point that it trips, hence why the electrician stated it was the PC – the last thing plugged in that caused it.

Is there anything I can do to isolate these appliances? The cooker socket does not have a normal socket with it, so can’t use that. I can’t even tell at the moment what ring is causing the grief, there are 3 in my house, 1 for each storey.

I have a multimeter, so is there any tests I can do, as a DIY man. I am loathed to get an electrician in at the moment, as sometimes its days between trips, sometimes 5 mins, unless there are tests that would answer the question quickly, at small cost.

Should I replace the RCD?

Thanks for reading, and sensible suggestions please.

Gary

 

[sparkybird]

Only quickly read your post, but i would suggest as an interim putting the trippy circuit on an rcbo (ie removing it from the RCD side of the board) so that you are not left powerless when the RCD trips

SB

 

[ban-all-sheds]

RF suggested that very thing 2 years ago....

 

[GForrow]

He did, and I didn't understand it then. I think I now get the gist of the this.

I have three ring main circuits, one for each floor. If I move one over to the non RCD side, and use an RCBO, and the RCD trips, I know its not that circuit. If it is that circuit, then the RCBO trips - Is that right.

I can then slowly move appliances over to the now non-trippy circuit on the RCBO to try and identify which appliance is causing the trip.

I hope I have understood right, and now to investigate RCBO. PLease let me know if I have got this completely wrong

I've got a 32amp Wylex MCB, so I presume a 32amp RCBO 30mA to replace it??

Ta

Gary

 

[PrenticeBoyofDerry]

You need to install RCBO and swap the problem circuit, which seems to be washing machine/dishwasher one to this and see if this trips if not and the RCD dosn't either you've cracked it.
If either does you have a problem still with earth leakage on the circuit of the device that tripped.
If it's the RCBO with W/M and D/W on it then the circuit or an appliance that is plugged into it, is causing it to trip.
If it's tripped RCD side then swap another circuit until problem is cured or you have intendified the circuit with problem, then again it's either circuit or appliances plugged in.

32amp Wylex MCB, so a Wylex 32amp RCBO 30mA to replace it

 

[flameport]

Rather than wasting even more time, why not just get someone to test your installation and appliances?

 

[PrenticeBoyofDerry]

Don't rush the OP, It's took two years to work out RF suggestion

 

[GForrow]

I had someone in, as I stated, and they said it was the pc. That was proven incorrect only recently, wife works from home, needs pc on. My two week holiday was ideal opportunity to unplug it. So with the power still tripping, that expert was proven wrong. Previous to that, not long after I moved in, I had someone else sent by the builder as well, there reason - Too much plugged in. Doh! So I can't use the sockets in my house then. - Much laughter ensued when he left.

The two year gap has really been trying to understand the issue. Turn off the garage MCB - Does it trip, maybe wait a couple of weeks, then it would - Try the next thing. Sometimes we could go weeks with nothing, then have a bout of never being able to keep the RCD on.

So now I have decided to do something about it, hence coming back on here, and researching more. I now understand where RF was coming from back then, and others have given more information this time.

So yes its been a while, but I will get it sorted in the coming weeks, I think

Cheers.

Gary

 

[OilLecky]

There is another "DIY" test method that you could try.

Buy a cheap 13A plug type RCD which you plug into your wall socket and then plug your suspect appliance into it.
(Screwfix sell them for just under £7.00 and several stores like B&Q have them but they are a bit dearer.)

The device will trip if it is on the defective appliance. I'd start with the dishwasher then the washing machine.
If your Distribution Board RCD trips and the one on the suspect appliance does not then that appliance is not causing the fault.

It may be a long winded way to do the fault diagnosis but it is cheap and simple.

 

[ColJack]

unfortunately the rcd in the board is more likely to go first, it's already got leakage on it from other things so will take less of a leak on the appliance to trip it..
unless you can get a plug in RCD that is rated at 10mA rather than 30mA..

 

[GForrow]

I've been looking for a 10mA RCD plug type adaptor, and can't find one anywhere, so I will resort to the RCBO option.

Just a query - Wylex RCBO - B or C?? I can get one from Screwfix locally, but its a curve C. B seem to be available on the net and are cheaper, not sure of the benefits.

So can someone explain, in laymans terms the difference, and whether a curve C is good to use, and I will then get it sorted this weekend, woohoo after 2 years

Gary

 

[ColJack]

it's all to do with the time / current curve of the breakers..

I don't have the exact figures memorised so I'll use examples instead..

a B might trip in 0.1 seconds at 5x it's rated current, a C will do the same at 10x and a D at 20x..
so the higher the letter (?) the more of a surge it can take..

for a C to operate you need a lower maximum Zs than a B..

 

[ban-all-sheds]

//www.diynot.com/forums/viewtopic.php?p=76467#76467[list]
[/list]

 

[GForrow]

Thanks for that, very useful. Linked page indicates that a C may be adequate for a socket ring but a B would be better. I will have to order a B then by the looks, oh well another week before it may get fixed, not long in my plans,

Cheers for all the help and info chaps, a vast wealth of knowledge here.

Gary

 

[ColJack]

wylex is popular many places, try an electrical wholesaler or even B&Q should do them..