RCD Tripping out

[Steffan]

THIS IS FOR ELECTRICAL NEWS ONLY

 

[pc1966]

Do you mean R1+R2, or the ring end-end r1, r2, rN sort of thing?

Sound like you still have loads on the circuit, so L-E link for your R1+R2 test is also linking N-E and tripping a common RCD?

 

[ebee]

"on linking out the circuit breaker for the circuit to earth to do the test "

Why are you linking the breaker? I advise against it.

Remove all conductors for that circuit prior to testing and usually you`ll have 6 conductors on a plain ring or 9 conductors if a spur is at the origin.
Then you can perform r1 + r2 to calculate R1 + R2 (of the ring itself) and do the "fig 8" test if appropriate too to find bridges and spurs to correct R1 + R2 values.

Hope that helps

 

[littlespark]

Working in a live board.... tut tut

?

 

[telectrix]

confused. do you mean r1,r2, etc., or R1,R2, etc., and if so why attempting with circuits energised. these are dead tests.

 

[DPG]

OP has been back, but not replied.

 

[timhoward]

I suspect we are misunderstanding him.
We don't know it's a ring final circuit.

 

[timhoward]

He might be using my last resort method if the board is a complete rats nest. Taking live out of breaker, putting it in earth bar. Then measuring R1+R2 the other end. Any loads can then trip rcd via the still connected neutral, so taking N out is important.
This method doesn't prove cpc continuity as parallel earth paths may exist.
In short, as said above, removing all conductors is best.

 

[Steffan]

I suspect we are misunderstanding him.
We don't know it's a ring final circuit.

Sorry it's a new lighting circuit

 

[Steffan]

"on linking out the circuit breaker for the circuit to earth to do the test "

Why are you linking the breaker? I advise against it.

Remove all conductors for that circuit prior to testing and usually you`ll have 6 conductors on a plain ring or 9 conductors if a spur is at the origin.
Then you can perform r1 + r2 to calculate R1 + R2 (of the ring itself) and do the "fig 8" test if appropriate too to find bridges and spurs to correct R1 + R2 values.

Hope that helps

Sorry its not as

Do you mean R1+R2, or the ring end-end r1, r2, rN sort of thing?

Sound like you still have loads on the circuit, so L-E link for your R1+R2 test is also linking N-E and tripping

He might be using my last resort method if the board is a complete rats nest. Taking live out of breaker, putting it in earth bar. Then measuring R1+R2 the other end. Any loads can then trip rcd via the still connected neutral, so taking N out is important.
This method doesn't prove cpc continuity as parallel earth paths may exist.
In short, as said above, removing all conductors is best.

It's a lighting circuit

 

[Steffan]

Working in a live board.... tut tut

?

Not live circuit breaker down just linking out at the breaker so I can do a r1 r2 continuity test at the light fittings

 

[timhoward]

Sorry it's a new lighting circuit

Not live circuit breaker down just linking out at the breaker so I can do a r1 r2 continuity test at the light fittings

No worries.
To get any more help (if you still need any) you need to describe exactly where you had all three conductors connected in the consumer unit.
Was it live and earth in the top of the breaker, and neutral connected to the neutral bar.
Or a link from the top of the breaker to the earthing bar?

I personally prefer testing the circuit before connecting anything to the consumer unit - I can keep a clearer mind that way!

 

[Steffan]

No worries.
To get any more help (if you still need any) you need to describe exactly where you had all three conductors connected in the consumer unit.
Was it live and earth in the top of the breaker, and neutral connected to the neutral bar.
Or a link from the top of the breaker to the earthing bar?

I personally prefer testing the circuit before connecting anything to the consumer unit - I can keep a clearer mind that way!

Thanks was a link from the earth bar to the circuit breaker but the neutral was still connected do the same method for all other radial circuits example smoke alarms radial sockets cooker etc. And never have a problem? Thanks again

 

[timhoward]

Thanks was a link from the earth bar to the circuit breaker but the neutral was still connected do the same method for all other radial circuits example smoke alarms radial sockets cooker etc. And never have a problem? Thanks again

I think @pc1966 nailed it in the very first reply. Basically there must be something connected in the circuit.
If you do a continuity test between L and N and it isn't infinity then that will prove it.
There is then a path from the consumer unit, down the Neutral conductor, through the lamp, back down the live, to the earthing bar.
That will cause an RCD to trip as not all of the return current from other circuits is passing back through the RCD so it sees an imbalance.

When testing other types of circuits you probably have sockets turned off, cooker turned off, maybe smoke heads removed, basically no Live to Neutral path.

In general I don't like this test method as it's better to ensure you are only testing one earth, and therefore verifying earth continuity, and not getting a false result from any other earth paths (e.g. gas bonding on a boiler, or supplementary bonding in a bathroom etc.). So I prefer to remove the earth from the earthing bar for the test.
Hope that helps a bit.

 

[Steffan]

I think @pc1966 nailed it in the very first reply. Basically there must be something connected in the circuit.
If you do a continuity test between L and N and it isn't infinity then that will prove it.
There is then a path from the consumer unit, down the Neutral conductor, through the lamp, back down the live, to the earthing bar.
That will cause an RCD to trip as not all of the return current from other circuits is passing back through the RCD so it sees an imbalance.

When testing other types of circuits you probably have sockets turned off, cooker turned off, maybe smoke heads removed, basically no Live to Neutral path.

In general I don't like this test method as it's better to ensure you are only testing one earth, and therefore verifying earth continuity, and not getting a false result from any other earth paths (e.g. gas bonding on a boiler, or supplementary bonding in a bathroom etc.). So I prefer to remove the earth from the earthing bar for the test.
Hope that helps a bit.

That's great thanks very much for your quick reply ?