Ketech 65 trips RCD when Zs testing at Light switch

[Deleted member 72666]

Am I missing something here, Zs readings should be taken at the furthest point which would usually be at the light fitting in this case?

 

[KingKenny]

Am I missing something here, Zs readings should be taken at the furthest point which would usually be at the light fitting in this case?

No, mate - You're not missing anything - it was the end of a long day for me, I was getting familiar with the almost brand new KT65, let alone my first full end-to-end test of an installation I'd done. The manual indicated I could take the reading at the switch and I missed the obvious. My fault. -------------- I'm not due back on site till next week, so I'll take the reading then. I SHOULD have copped it when I successfully took RCD trip readings at the same light switch about 20 minutes afterwards on L, N and E, but like I say - I had a brain trip!!! --------------------------------------------------------------------
genuine Thank You to everyone who responded. -------------- KK

 

[virge]

You can do it with a Fluke - N & E leads to Earth.

Is it just the Kewtech for some reason?

I have a fluke 1653 ,am i understanding right then that you can test for zs at ceiling rose with N & E leads conected to Earth in the ceiling rose and L conected
to L or SW Live

 

[Geoffsd]

I am not saying you should, because there is a neutral at the rose

but at the switch it will work and confirm the earth is good.

 

[virge]

Hmm think i will give that a go ,any more handy tips Geoffsd ,can you tell me the difference between a short and a short circuit sounds dim i no but just need to understand the meaning (still at college) thanks

 

[KingKenny]

Just to let everyone know - Managed to take quite a few Zs readings at end of lighting circuits now with the Kewtech 65. Pretty easy when you know how! - Fairly sure we're not SUPPOSED to, mind ... as in effect it is working live, no?

 

[virge]

Hmm think i will give that a go ,any more handy tips Geoffsd ,can you tell me the difference between a short and a short circuit sounds dim i no but just need to understand the meaning (still at college) thanks

Sorry ment short circuit and a dead short thanks

 

[Geoffsd]

meant short circuit and a dead short thanks

A dead (bolted) short is just a common term for a short circuit with negligible impedance.