TT RCD problems

[[email protected]]

Hi All,

i have been called to a rural property with a TT supply. The property has recently been rewired by another contractor but he refuses to come back to fix the problem.

it is a large villa and has 5 rcds protecting various circuits, pool, aircon, sockets, oven, hob, etc etc.

Ever since the installation was complete the owner has had nuisance tripping of RCDs.

inhave been and tested for crosses neutrals, polarity, insulation resistance, RCD test etc.

i have visited the property this morning and three out of the 5 RCDs had tripped.

Has anyone had experience of this, can the external supply cause this?, if so what is the solution?

Help, advice would be greatly appreciated!

Mark

 

[Bruspark]

Have you tested the Earth rods ?    And measured any leakage flowing through them ? 

 

[[email protected]]

I have looked for the earth rods but cannot find them. I did not have my earth loop tester with me this morning so could not test this. I did notice that there was a 4v difference between L-N reading and L-E,

L-N 237v L-N 233v

Could a resistance problem with the rods or may cause this?

(Mat)

 

[Bruspark]

Well it’s an essential test (and inspection) before looking for more complicated theories.

4v is plenty to enable N-E leakage to trip RCDs

 

[[email protected]]

Thanks, will test the rods or mat, and see what I discover.