rcd issue

[ample current]

hello every body,

I have been to a house this evening after a customer calls regarding a tripping rcd, I did the usual, all circuits off then on 1 by 1, it seems to randomly trip regardless of which breaker is switched back on, even mcbs on the non rcd side caused it to trip, which I thought a odd. Ramp test proved the rcd faulty, wouldn't trip when 33mA were reached, normal I delta n woudnt trip in 300mS. The board was a slit load vynckier installed when the house was bit probably mid 80's, so I doubt much chance in finding a replacement rcd.
the thing that got me the most was the fact circuits not connected through it tripped it???
Would the fact the rcd was not functioning properly (as in not tripping when tested) cause it to trip for no apparent reason like switching the oven on (oven no connected through rcd)

 

[Leesparkykent]

Did you ramp test the RCD with the loads disconnected? Also did you carry out any IR tests?

 

[telectrix]

test the RCD again with nothing connected to it's output. bet it's fine, then start looking for a neutral/earth fault.

 

[ample current]

Did you ramp test the RCD with the loads disconnected? Also did you carry out any IR tests?

Getting the RCD to stay on with any load connected to the rcd or not was near impossible, what difference would that make anyway. IR between line and E were ok. Customer has decided on an new CU after finding a couple of other faults so will be carrying more comprehensive tests then.

 

[Farmelectrics]

What was your ir between l. And. N

 

[Farmelectrics]

Sorry neutral to earth

 

[Pete999]

Getting the RCD to stay on with any load connected to the rcd or not was near impossible, what difference would that make anyway. IR between line and E were ok. Customer has decided on an new CU after finding a couple of other faults so will be carrying more comprehensive tests then.

As Tel suggested probably a N-E fault, have you tested IR N-E? if so what were the results?

 

[ample current]

sorry for late reply, have been way, ok, no neutral earth fault, I did however find 3 socket outlets wired up with neutral live reversed, one in the kitchen possibly done by the kitchen fitter some years earlier but the other 2 were done when the house was originally built 25+ years ago, there were also couple of surge protector leads that were faulty, however these were unplugged when I initially looked for the cause of the tripping.