Just been reading your thread Joe and wanted to add my congrats. The NIC inspectors are a good bunch even, if they are bookworms.
Most can quote the regs without even looking it up.
Just wanted to be sure you are clear on a couple of points with regards to your tt readings.
Mainly that you need to relate two methods of fault current protection in a TT system.
a) is your fault current from phase to earth that is dealt with by your 30ma rcd, mainly because with the higher Ze values its the only way to achieve disconnection times. Remember ohms law and the magic triangle V=IxR. The value of 1667 ohms makes sense if you apply it to the 50v rule in other words I= 0.03 x R=1667=V which is our 50 volts.
b) is your fault current from phase to neutral and this is taken care of by your mcb, ok an mcb is quite capable of giving earth fault protection in lower earth resistance path systems like tn-s 0.8 ohms or
tn-c-s (pme) at 0.35 ohms (max recommended) But as said our rcd is coping with that one on TT.
Anyway for phase to neutral we can rely on table 41.3 because our phase to neutral loop will (or should) be much lower and hence our generated pfc much higher,again ohms law will bear this out.
I expect a few of the lads on the forum will be having a chuckle for my waffling on. But I have seen some good sparkies make simple mistakes for years and not realise, just because they haven't grasped the basics early in there careers. For example taking an earth loop and there pfc from the same reading
(Highest pfc will almost always come from phase to neutral) or high ring main continuity (Forgot to null the leads)
Anyway I will shut up now
Well done to you for getting through.