RCD Tripping

[BillySparks]

I have been doing a periodic test on a property for a guy i do alot of work for, there was loads of things wrong no gas or water bond there was a sub main in the main house that was over 3 meters away from the mains with just tails coming out a henley block feeding it, also its a tt system so its just using a main rcd that wasnt tripping in under 0.4 seconds so I have changed it today put everything back on all fine nothing tripped did an rcd test all good also did a quick loop test everything fine, I have since come home then the guy has phoned me up he has no power the rcd has tripped I just thought nusiance tripping, but now the rcd is randomly tripping and wont trip under rcd test and now i cant loop test it just trips the rcd out, I have manged to get everything back on and holding in, I have just got home and cant think why it would be doing it any ideas?

thanks

Billy

 

[timo1]

May seem like a long shot but it could be the rcd. I have had two brand new ones(from different manufactures) recently test fine initially but a day later trip and then the test button would not work and they had to be returned. I had every socket cover off as I could not believe it could be the RCD. I now will only fit RCBOS to new boards as at least that way you can identify the circuit easily in the event of a fault. Good luck,

 

[IQ Electrical]

I have been doing a periodic test on a property for a guy i do alot of work for, there was loads of things wrong no gas or water bond there was a sub main in the main house that was over 3 meters away from the mains with just tails coming out a henley block feeding it, also its a tt system so its just using a main rcd that wasnt tripping in under 0.4 seconds so I have changed it today put everything back on all fine nothing tripped did an rcd test all good also did a quick loop test everything fine, I have since come home then the guy has phoned me up he has no power the rcd has tripped I just thought nusiance tripping, but now the rcd is randomly tripping and wont trip under rcd test and now i cant loop test it just trips the rcd out, I have manged to get everything back on and holding in, I have just got home and cant think why it would be doing it any ideas?

thanks

Billy

You don't mention anything regarding insulation resistance readings....

Was the existing RCD time delayed?

 

[BillySparks]

yeah rcbos are definatly much better at least you dont lose evrything in one hit, I havent actually changed the board in this case its a newish board old style mk board so just fitted a new rcd as the old rcd wasnt tripping in .4 secs, the only conclusion I can come to is its a faulty rcd, cant really see it being anything else. will pick one up first thing and change it fingers crossed thats what it is.

 

[BillySparks]

You don't mention anything regarding insulation resistance readings....

Was the existing RCD time delayed?

Hi yeah sorry didnt mention that insulation resistance was all clear on every circuit, so it cant be that, yeah the existing rcd time was delayed hence the change of a new rcd, so changed the rcd tested it worked fine also did a quick loop test and that was fine, packed up went home and then got a call to say he had no power, now when I test the rcd I get nothing it doesnt even test and when I do loop test it knocks the rcd out

 

[Jimmyb]

tt system 0.4 ?????

 

[IQ Electrical]

Hi yeah sorry didnt mention that insulation resistance was all clear on every circuit, so it cant be that, yeah the existing rcd time was delayed hence the change of a new rcd, so changed the rcd tested it worked fine also did a quick loop test and that was fine, packed up went home and then got a call to say he had no power, now when I test the rcd I get nothing it doesnt even test and when I do loop test it knocks the rcd out

When you say you do loop tests, are they 'no trip' loop tests or full current?

 

[BillySparks]

I tried it on both no trip and full current

 

[IQ Electrical]

If it tripped on 'no trip' then it would suggest a good few milliamps are already being seen and the 5 or so milliamps of test current are tipping it over.

Try a ramp test and see where the RCD is tripping.

Were/are RCBO's in use for the sub-circuits?

 

[BillySparks]

yeah it did trip on no trip. thats a good idea I will try the ramp test going back there first thing, there are no rcbos there is a sub main that has rcd protection then just mcbs.

 

[Engineer54]

If the original RCD was an S type RCD it won't trip in 0.4/0.2 seconds will it ...it's time delayed!!!!!

 

[Deleted member 9648]

tt system 0.4 ?????

Wot Jimmy said.....should be 0.2....hope you didnt put 0.4 on your PIR schedule.