spur socket tripping RCD (mcb off)

[abrli]

Hello all,

Hope everyone's doing relatively well given the unique circumstances.

I'm a fairly new DIYer and this weekend I attempted something that should be relatively straightforward - spurring a double socket off a rotary isolator switch (existing circuit is used exclusively by electric car charger).

With the MCD off, RCD was tripping as i switched the rotary switch from OFF to ON. I understand it would happen when earth and neutral accidentally touch, but I struggle to see how it's happening here. RCD is only tripped when the rotary switch is moved to ON position.

Feels like I must have made a rookie mistake somewhere.. Any help or advice would be greatly apprecaited!

Thx!

 

[abrli]

Just to make myself clear. The picture is the existing isolator switch wiring with the points of my spur conenction marked.

 

[SPECIAL LOCATION]

I would guess the rookie error was the difference between

(a)  Turn power off - Do alteration - Turn power on..

and ...

(b)  Test & verify integrity of existing circuit proposed to amend..  Design amendment,  Do alteration,  Verify dead tests, Re-energise, Do live tests, Issue BS7671 certificate..

problems only normally occur if standard BS7671 procedures are not followed.

Guinness   

 

[ProDave]

We can't see anything unless you post a picture AFTER your modifications, including the wiring of the socket.

 

[Andy™]

im going with squashed wire in the backbox of the socket

but as above, this should have been found by your testing before switching it on...

 

[Murdoch]

Maybe I'm missing something here, but if the circuit is dedicated to the car charger, what made you think adding a socket was appropriate or sensible?

Whats the rating of the MCB?

 

[poni]

what makes you think the fault is with the switch and not the new socket you have fitted 

again this needed testing to make sure it was safe to use,

the RCD has saved someones life