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Some very good points John but contrary to logic and well established electrical principles, I would still not want to touch something sitting at 230v even if not in simultaneous contact with an earthed item or an unbonded extraneous item... As you have said, the 22kohm rule is not perfect!

I agree with your main point but was just looking at it from a different perspective. There are many scenarios to consider. A modern house may be piped in entirely plastic (including incomers) and only non extraneous runs of copper inside, therefore having no MPBs (unless pointlessly clamped to...

As others have said, never bond anything unless it is classed as an extraneous part (22kohms or less when tested to the MET) Consider especially PME systems and potential (although unlikely) loss of neutral! Or put another way... ‘would you take a bath on your neutral bar???’ :shock:

Agree Spark123 - also phohibited by BS7671 (546-02-08 )

If it's TT then it needs an electrode - 542-02-04 The 'earth continuity satisafctory' only applies to your earthing within the installation and does not relate to satisfactory/unsatisfactory Ze Hope this is of some help!

'Why is it that in all DIY Books the way they say to run power in outbuildings is by a piece of T+E run in PVC Round Conduit, buryed in a trench covered with paving slabs, but never say to use SWA.' Because they are wrong! :x

Yep I know there are always exceptions! :) Lighting is a different matter and as you say, it is good practice to split flourescents across the three phases when moving machinery is involved! It's because a motor and a flourie on one phase can reach similar rates of...

As a rule of thumb, I like to keep different phases to different rooms (if possible) If in close proximity then correct labels cover you in any instance (even two phases in the same gridswitch etc)

I was thinking that maybe you could get away with a smaller CSA as well but your calculations are wise! You wouldn't want to get that one wrong! Besides... bigger volt drop means a higher electricity bill! If they do want to go ahead they'd better do so soon as the price of copper is shooting up!

Your electrical theory is good Adam! Remember those theorectical R1+R2 predictions will be increased slightly by the connections and contacts! Also Ze varies around the day and measured Zs seldom equals Ze + (R1+R2)! The idea you propose will NOT be cheap! :(

Thermal Insulation will halve the current carrying capacity if the cable passes through more than half a metre of it (The correction factor (Ci) is 0.5 for 500mm of Insulation and over) EDIT: Whoops forgot to mention... the cable has to be fully surrounded!

A glowing 'Voltstick' is great for this!

I have a collection of different lock-off devices - some 'universal'... None of them work on all breakers I encounter but I can always find a compatible device from my selection!

There is nothing wrong with a spare breaker from a regulatory point of view but I agree with John D... Blanks are cheap and readily available so there is really no excuse for using circuit breakers although it is still better than a gaping hole!

Only certain types of load (such as motors) give a perfectly balanced three-phase loading. With seperate loads on seperate phases you could never hope to balance the phases and this imbalance is not a problem. The closer to balanced they are, the less current returns via the neutral (which is...

The emphasis being on 'hard to work with'. I could fit a Crabtree Starbreaker in HALF the time (I have fitted both CU's)

:lol: Sometimes it makes you think they DON'T want you to be able to terminate the fitting!

I'd go for a bit of Butyl! :wink:

'totallyspies will be along any time now, suggesting an armadillo kit, or some SWA cable variant' :lol: I was waiting for somebody to make a joke about that!

I see what you mean Crafty! Like SS says - why not DIY? You could pick up a cheap drill & bit and use it for future projects? I suppose testing is your only real problem but if you want to do electrical work in the future (as your posts suggest) then an all in one tester maybe a good...