Originally Posted by Ross Trician

evening chaps,
just to fill you in on a few more bits and to make things a bit clearer.

The incoming supply mis 3 phase which then uses the individual phases to feed various isolators and dis boards etc.

these are somer of the test results I did get.

ring was, L-L, 0.69 ohms. N-N was 0.66 ohms, cpc-cpc was 0.98 ohm.
L-N figure 8 1.34 ohm.
L-E fihure 8 was 1.56 ohm.
R1+R2 was 0.45ohms.
Ring Zs was 3.64ohms

Shakey, you say that the pfc is the right reading but needs to be doubled because it is 3 phase, can you tell me what difference that makes at the C/U as it is only fed with a live and neutral.

also can some of you who are more knowledgeable than me confirm I am interpreting this right,
in GN3 it states the max Zs for a type 1, 16 Amp, bs3871 CB is 3 ohms?
and for 32Amp CB it is 1.5ohms.
therefore the ZS readings I have are too high and presumably due to there being no earthing arangments???

also you say about putting a spike in for the whole system, would this then not make me "responsible" for the whole system?
my thoughts were to simply provide the earthing for the instalation I am working on and if they wish to "put right" the rest of the system then that would be a seperate issue.

I am initially working to the 16th, going on the 17th update course in couple of weeks.
could I put an rcd unit inline after the isolator to cover the whole system rather than changing both boards, advice on you ideas of instalation experience appreciated.

thanks Ross