RCD wont reset even with electric off

[FirstTmeBuyer]

Hi my RCD tripped a couple of times today with only the downstairs lighting circuit on which is on the non RCD side. All the other MCB's were in the off position.

I reset it but it tripped again after 30 seconds or so. Now it won't even reset with the main power switch off. I usually turn the main power off then flip the RCD down and then back to the top but even while the main power is still in the off position the RCD switch wont stay in the top position. I don't think it's tripping it just won't hold in the top position and will only stay in the tripped or off position.

Does this sound like a faulty RCD or could something else be at fault.

 

[JohnD]

sounds like it is faulty, but, to be sure, turn off power and remove it from its connections.

use a meter on terminals top and bottom before removing it to make sure no power is getting in.

 

[DESL]

I had the same fault on a CU where the neautral had not been nipped up at bottom of RCD and had melted the RCD. This wasn't evident until cover was removed.