how do i test a rcd thats not in the db

[rabj67]

i have a rcd fitted in the trunking in an office but at the db i have a mcb i have tried to do a R1+ R2 test but as my mft uses 200ma it trips the rcd any advice would be greatfull

 

[pc1966]

Safely isolate, disconnect and short both ends L-E (so L at MCB to earth bar, and L to CPC at end point) then open (trip) the RCD and measure R1+R2 between L in and L out of the RCD.

 

[timhoward]

That's how I'd do it.
It might help to think of it as doing the test in two sections, link R1 and R2 at DB, measure at RCD the CPC to L feed, then link R1 and R2 at circuit end and measure at RCD the CPC to L load. Then as it's resistances in series, simply add them.

But then in fact you have done the exact same connections that @pc1966 suggested and in fact you can do the test all in one go by thinking of it as a big loop and measuring it all in one go.

 

[timhoward]

By the way, be careful IR testing that circuit!