RCD Keeps tripping

[James9292]

I have recently added two double sockets in a lounge original nor realising that the source was a spur that someone had already wrongly spure, so two existing double sockets a spur from a spur I then added 2 sockets across the room on a back to back wall essentially creating 4 spurs which obviously tripped the RCB.After realising the mistake I added a 13A fuse before the first socket to prevent tripping and make the original sockets safer also so the order now goes spured power into 13A fused split to feet 2 sockets that in turn feed 1 double socket each. Unfortunately the problem has persisted I have tested all sockets with a fault plug and all register correctly wiring and no faults. I don't know if this is earth leakage from an appliance or RCB failure the main CU only has 2 RCBs one for lights and one for the entire ring Main B32 30mamp load and another B6 for the lights and 1 MCB each which seems minimal

 

[James9292]

Are we sure that it's an RCD that's tripping and not a circuit breaker. If it takes a few hours to trip, it could be due to the circuit being overloaded. Maybe...

Defo not the cbo its every time RCD

 

[littlespark]

Is it when things are plugged in?
First rule of rcd club is to unplug everything, not just turn off at the wall.
That rules out faulty appliances if the rcd continues to trip.

 

[pc1966]

Are we sure that it's an RCD that's tripping and not a circuit breaker. If it takes a few hours to trip, it could be due to the circuit being overloaded. Maybe...

It could also be a N-E fault that only shows up when something else takes a large current.

 

[johntheo]

If it is a N to E fault then you could expect this to show up as the current flow through a (the) neutral is increasing as there normally is only a volt drop or so with low flows which then increases with increasing current flows but even if there is only say 1 volt in the neutral cable at the fault location; a fault resistance of ~ 33 ohms will have no bother in tripping the RCD, a simple N to E resistance test with a multimeter could easily pick this up, if no fault the resistance will be infinity.

 

[James9292]

If it is a N to E fault then you could expect this to show up as the current flow through a (the) neutral is increasing as there normally is only a volt drop or so with low flows which then increases with increasing current flows but even if there is only say 1 volt in the neutral cable at the fault location; a fault resistance of ~ 33 ohms will have no bother in tripping the RCD, a simple N to E resistance test with a multimeter could easily pick this up, if no fault the resistance will be infinity.

I've had purchases an advanced kewtech plug tester that tests the loop and continuity also. Last night we turned off the power to the fused spur/s and it was still tripping does this mean that the fault has to be elsewhere? I am guessing at moisture or water in the outside sockets after this heavy rain etc!

 

[James9292]

I've had purchases an advanced kewtech plug tester that tests the loop and continuity also. Last night we turned off the power to the fused spur/s and it was still tripping does this mean that the fault has to be elsewhere? I am guessing at moisture or water in the outside sockets after this heavy rain etc!

And yes I don't have the full fluke or kewtech etc multimeters as I'm not fully qualified yet.

 

[LastManOnline]

I've had purchases an advanced kewtech plug tester that tests the loop and continuity also. Last night we turned off the power to the fused spur/s and it was still tripping does this mean that the fault has to be elsewhere? I am guessing at moisture or water in the outside sockets after this heavy rain etc!

Not necessarily. A fused spur only breaks the live, so a neutral to earth fault in the isolated circuit will continue to trip the rcd when sufficient load is flowing in the home. Neutral to earth faults are usually the most challenging faults to locate.

 

[johntheo]

Maybe remove the N & E from where the new fused spur is connected to "the other" spur.? or at least the N.

 

[James9292]

Maybe remove the N & E from where the new fused spur is connected to "the other" spur.?

I will try that but I have already rewired those connections and replaced the fuse face and socket face of 2 of the spurs on of which has a loose neutral connection point. But yes that sounds like the best way to confirm if the new wiring is the problem

 

[UNG]

I've had purchases an advanced kewtech plug tester that tests the loop and continuity also. Last night we turned off the power to the fused spur/s and it was still tripping does this mean that the fault has to be elsewhere? I am guessing at moisture or water in the outside sockets after this heavy rain etc!

Without an IR tester you are clutching straws as to where the fault is, personally I would try to narrow down where the fault is using an IR tester and depending on the IR level possibly use a cable tracer to home in on it

 

[timhoward]

Deleted

 

[MJPD29]

Would splitting the ring main onto more CBOs prevent th

What is the best way to trouble shoot that as I'm guessing it would be to go over all the new connections in turn also this happens every 4 to 6 hours or more sometimes with heavy load items ie kettles etc also happens under low load in the night

Best trouble shooting at this stage is to call a competent electrician. With all due respect a little knowledge can be dangerous and in this case you are making the installation much less safe with the work you are doing.

 

[James9292]

Best trouble shooting at this stage is to call a competent electrician. With all due respect a little knowledge can be dangerous and in this case you are making the installation much less safe with the work you are doing.

Thanks for all the response and advice guys and gals turned out it was a L to E fault from 40+ year old wiring degrading and unfortunately the fault is in the hard-core wiring not at any of the socket points or CU the multimeter was giving a reading of 50 to 90ohms at all socket outlets

 

[mechelec]

A spur from a spur wouldn’t trip an rcd.

an rcd or rcbo looks for an earth fault whereas an mcb looks for overload. (Nothing actually plugged in, no load)

you’ve done right by creating a fused spur, and by limiting the supply to 13A.

if the rcd trip is constant, check for a squashed cable behind a socket.

Does an RCBO not give earth fault and over current protection as well ?

 

[James9292]

Does an RCBO not give earth fault and over current protection as well ?

Yes that's why it's been tripping at increasing intervals for a week before refusing to turn on at all it is tested as functioning