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If you tt the barn the earth would be divorced, am i misreading

Providing theres an equipotential zone in the barn, i see no issue using the tncs, though tts good to, your shout. Is volt drop ok?

.Its not to much of an issue, just need bonding as it enter the barn, problem may be, tncs 10mm bonding req, do you have a bonding conductor from the met to the barn?, or a cpc which can be utilized for both?

A lot will depend on the supply and frequency of switching

Do you have a equipotential zone in the barn? You have a similar scenario where a row of terraced on tncs share metalic services and one of the terraced is tt. Some diverted current may flow in the tt terraced, though they must feel its not an issue as theres no regulation covering it. Its an...

Those gloves are fiddly to work with, though it becomes easier when their made fingerless:p

So you R1+R2'd a live circuit? Who ever installed that with rcbo's off an RCCB should be shot (or at least shown reg 531.2.9). Indeed he has:red card

Its possible sellers, though it need not be a borrowed neutral,just a circuit energized for the current to flow to the neutral bus bar, there the current would divide, some down the neutral and some through the circuit under test shorted to earth,the cpc would be required to remain in the earth...

I disagree On a PME supply the 'Earthing Conductor' performs the function of a 'Bonding Conductor', and is required to fulfill the CSA requirements of a 'Bonding Conductor', but that doesn't make it a 'Bonding Conductor'...i.e. it would never be referred to as such. If its not a bonding...

In a tncs a earthing conductor is combined with the function of a bonding conductor, also theres nothing wrong with a combined cpc and bonding conductor

Stick a clamp around the line and neutral and what leakage exists, carry out a ramp test, it may be that the leakage is very close to trip current of the rcd. Fridges are a common culprit, the list is quite long though.

Ive mounted 16mm swa no issues, just ensure the fixings are adequate. The other important factor is the length, are we talking a few meters or many?

I was getting paranoid for a minute, thats what my footie mates called me when i used to play LOL

273 to 317

The resistance figures in appendix 4 are based in an operating temp of 70 C spin, so no need to apply a factor.

Sorry Paul, i couldn't resist:D

BS 7671 places no time on over current, other than to say it needs to be interrupted within a time so that the cable max temp is not exceeded, saying that the k factors in the regs are for upto 5 secs disconnection, so this tends to set a upper limit of 5 secs, though other k values may be used...

.I maybe missing something here, but why are you applying a factor of 0.8 to the ccc of the cable?