Cant get a Zs reading ? ? ?

[NoSparks]

Hi, I cant get a Zs reading from the majority of my new circuits. I do get a reading between the incomers to the d.b and the main earthing conductor and I can get the RCD tripping. The system is TT and its a total rewire. Any help would be appreciated.

Go back to the beginning. You get a Ze reading between incommers and main earth. I presume this is using the normal Ze measurement. Can you get a Ze measurement between incommers and main earth using the RCD function?

If the answer is No then you have a meter problem. (The only difference is the way your meter is measuring Ze; one way it works, one way it dosn't). Solution: use a calculation for Zs [= Ze + (R1 + R2) ]


If the answer is Yes then you have a connection problem. If you get a Zs measurement on the RDC input terminals, but not on the RCD output terminals (using the RCD function in both cases) then its the RCD. If you have a Zs measurement on both sides of the RCD then progress through the circuitry until you don't get a Zs measurement. That will tell you where your problem lies.

 

[Joe S]

Go back to the beginning. You get a Ze reading between incommers and main earth. I presume this is using the normal Ze measurement. Can you get a Ze measurement between incommers and main earth using the RCD function?

If the answer is No then you have a meter problem. (The only difference is the way your meter is measuring Ze; one way it works, one way it dosn't). Solution: use a calculation for Zs [= Ze + (R1 + R2) ]


If the answer is Yes then you have a connection problem. If you get a Zs measurement on the RDC input terminals, but not on the RCD output terminals (using the RCD function in both cases) then its the RCD. If you have a Zs measurement on both sides of the RCD then progress through the circuitry until you don't get a Zs measurement. That will tell you where your problem lies.

I will give that a go mate. I think I just leave my meter on the no trip function out of habit as nearly everything has rcd's now.