Crabtree RCCB 80A 30mA

[RmBo_0]

Hi,

I've just been to a job where the main switch rccb keeps tripping during the night. Haven't had chance to do continuity / IR tests yet as the consumer unit was in a corner cupboard with a revolving rack. So I just did an rcd test which tripped on x1/2 so I started switching the mcbs off one by one and re-testing. Till I got to a circuit that was a 16a radial socket into the loft with lights, CCTV, Ariel booster a bedroom socket and a shower pump all off an extension cable. The booster, socket and pump all being wired into a 13a plug I assumed that could be the problem. I unplugged it all and did the rcd test again and it tripped again at x1/2 but not at 0c but at 180c so i re-tested again and it didn't trip till it got to x1. It did this a couple of times then started tripping at at x1/2 again.

Could this be my tester giving inaccurate readings? or should I just wait till I've done the dead tests and see what problems that brings up. Any help would be appreciated.

 

[ste77]

can you test another RCD to see how your tester performs? also if the rcd is tripping during the night it could be a circuit thats either on a timer ie heating. other than that your looking at a faulty rcd. hope this helps

 

[Rockingit]

It sounds to me like you've got your problems mixed up here: the point of testing an RCD is to check that it's operating characteristics are correct, not whether the circuit/s it's supplying are fit. If you've an RCD that's tripping on 1/2 current then it's the RCD that's at fault, not the circuit.

If you've a bunch of electronics hanging on an RCD protected set of circuits then to see 15-20mA of 'normal' leakage is not uncommon, so if the RCD is overly sensitive then it will nuisance trip without a 'real' fault present.

Suggest disconnecting the RCD from circuit (or isolating all the MCB's) and doing a ramp test - this will show you the current that it's tripping at. If it's less than around 20-23 then swap it out for another.

BUT..... you might also have a faulty circuit or appliance somewhere as well, so do those IR's just to be sure. Let us know how you get on.

 

[telectrix]

was going to say similar but too busy on call backs. LOL. :35:

 

[Rockingit]

was going to say similar but too busy on call backs. LOL. :35:

It's only taken me about two years and 2,000 odd posts to finally beat you to it, Tel!

 

[RmBo_0]

Thanks for the replies. I cant get back till after christmas so I'll let you know how I get on. The bloke said it had been doing it for over a year, so a week or so didn't matter haha. I'll do the ramp test and see what results I get aswell of the normal dead tests on the circuits

 

[Rockingit]

Thanks for the replies. I cant get back till after christmas so I'll let you know how I get on. The bloke said it had been doing it for over a year, so a week or so didn't matter haha. I'll do the ramp test and see what results I get aswell of the normal dead tests on the circuits

That is almost your fault in itself - for some reason that I've never fully understood, it does seem to be that the more often an RCD trips, the more sensitive it becomes - so it's a vicious circle.

 

[Engineer54]

Replace this RCD unit, if it's been an ongoing problem for over a year, the mechanism is probably shot/worn anyway, with the amount of resets it's been subject too. Then carry out your testing to find any faults that might have been responsible

 

[RmBo_0]

Been back and it's tripping at 21mA so replacing. I've found a used one on eBay but would prefer a new one. Anyone know where I could get one

Model number 528/030
Thanks.

 

[worzol99]

Buy Residential RCCBs Crabtree 2P 30mA RCCB,80A Crabtree RS/380/030 online from RS for next day delivery.

would this fit rs are expensive though

 

[telectrix]

think i've got one. it's used but not abused. i'll have a look in a min.

 

[worzol99]

This ones new on ebay
Crabtree Split Load RCCB DP 80A 30mA 380/S030 | eBay

 

[RmBo_0]

If telectrix haven't got one then I'll have a look when I get home. On my phone at moment so bit if a pain looking through.

 

[telectrix]

just checked. the 2 i have is a 40A,100mA. and a 63A 30mA double width unit with the 2 prongs. soz.

 

[RmBo_0]

No problem thanks for looking. Worzol99 the one I'm after is different to s030 so not sure it would fit.