Faulty Wylex Rcbo

[pete1]

Hi, I added a new radial kitchen circuit at a property last week. The circuit has 1x double socket, 1x socket for an integrated dishwaher and a fused spur for a cooker hood and is protected by a 16A rcbo. When first switched on the rcbo immediately tripped. I checked all terminations, insulation resistance is good and I checked that the kitchen fitter had not damaged the buried cables. The rcbo has tripped several times now, even overnight with no load. I swapped it for another one yesterday but the customer called today saying that the new one had also tripped. I am aware of the Electrium recall in 2012 regarding faulty mcb's but have not heard of any problems with the rcbo's. I mostly use Crabtree Starbreaker for domestic work and have had very few problems, but was wondering if anyone had encountered similar issues with the Wylex rcbo's? Any help would be much appreciated! Kind regards, Pete.

 

[onions1066]

Have you checked the appliances plugged in?

 

[shanky887614]

I bet they have a dodgy extension lead thats the culprit

 

[uksparks]

Just out of curiosity, any reason you put in on a 16a and not a 20a breaker?

 

[uksparks]

When you first switched it on, was this after installing it and testing? Or was it working for a period of time then it packed up then you went over then switched it on?

 

[R G]

Try using a clamp meter with appliances running on ma range on the cpc

 

[pete1]

Thanks for the prompt replies! The only appliances that are plugged in are a brand new dishwasher and cooker hood but I guess they could be faulty? I used a 16A rcbo really because of the small amount of load, playing it a bit on the safe side I guess! I can see that perhaps it could point to an earth leakage will get my clamp meter on it tomorrow. Just seems odd that even with nothing plugged in it still trips. The rcbo tripped with a loud bang after initial switch on when carrying out live tests with nothing plugged in. After checking the terminations again it stayed on long enough to finish testing. When I got home the customer called saying that it had tripped a couple of times again.

 

[R G]

Well if it trips with nothing in do a ramp test on it ,,OH and test you circuit ,,

 

[Octopus]

Are they on an outside wall? is the sink adjacent? Moisture ingress somewhere?

 

[pete1]

There is a socket above the work top and the dishwasher below with isolator above on an outside wall but not near a sink, then on the opposite wall is the cooker hood. Just to confirm it is a new circuit, I went along to connect up and test after the walls were plastered for about 2 weeks and the new kitchen was fitted. Thanks

 

[R G]

Just to confirm ,,have toy done the IR tests ,,

 

[Octopus]

Had an odd one recently - no RCD but the MCB was going bang in style! Found one socket where the insulation was damaged and judging by the black mark in the back box it had been going bang. The only "clue" was that the socket wasn't tight.

 

[pete1]

Hi Ray, thanks for the reply. I carried out all testing, the IR results fine.

 

[R G]

If it went bang as you say with nothing plugged in and circuit is o/k , its goota be the a faulty rcbo , but if I were you I would try the ramp test and the clamp meter on the cpc , but with the info so far it does sound like a faulty one .,,,

 

[pete1]

Thanks. I will check the appliances tomorrow and ramp test the rcbo. I had hoped that the first one was part of a faulty batch but got the second one from a different supplier was exactly the same! Thanks again!

 

[GLENNSPARK]

If it went bang as you say with nothing plugged in and circuit is o/k , its goota be the a faulty rcbo , but if I were you I would try the ramp test and the clamp meter on the cpc , but with the info so far it does sound like a faulty one .,,,

if it went with a bang then this should suggest short circuit...as opposed to earth-fault..

 

[R G]

What I would suggest is ramp test without appliances plugged in and then test with appliances plugged in , and the difference would be the the leakage current , although the rcbo would have tripped by then ,, still worth a try,,,

 

[R G]

if it went with a bang then this should suggest short circuit...as opposed to earth-fault..

Thats exactly what I think but he says circuit is tested and o/k ??

 

[MDJ]

Can,t see it being 2 rcbos in a row that's faulty lol

 

[HandySparks]

.... The rcbo tripped with a loud bang after initial switch on when carrying out live tests with nothing plugged in....

If it's tripping with a loud bang, it's because there's a large fault current, either L to N or L to E. If it was just a little bit of earth leakage, it would just open with a click.

So, if it's doing this repeatedly, you're looking for an intermittent low resistance fault.