# When doing a r1 r2 test on linking out the circuit breaker for the circuit to earth to do the test the rcd trips out any thoughts on why this is happe

Discuss When doing a r1 r2 test on linking out the circuit breaker for the circuit to earth to do the test the rcd trips out any thoughts on why this is happe in the Electrical News - Electricians News area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum

THIS IS FOR ELECTRICAL NEWS ONLY

#### pc1966

Esteemed
Arms
Supporter
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 "

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

##### -
Esteemed
Arms
Working in a live board.... tut tut

#### telectrix

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

#### DPG

##### -
Esteemed
Arms
Patron
OP has been back, but not replied.

#### timhoward

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

DPG

#### 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 "

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?

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!

Reply to When doing a r1 r2 test on linking out the circuit breaker for the circuit to earth to do the test the rcd trips out any thoughts on why this is happe in the Electrical News - Electricians News area at ElectriciansForums.net