Voltage drop and ZS - Some thoughts

[GaryM]

I'm pretty sure a BS1362 fuse is rated to break 6kA, more than likely same as the B32 MCB supplying the FCU.
You'd need a Zs of 0.038ohms at the incoming side of the FCU to see fault currents that high anyway which is pretty unlikely!

Where a 60439-3 (and 5486-12) CU comes into it's own is with a type 2 1361:1971 fuse rated at no more than 100A - with this combination the short-circuit rating of the protective device in the consumer unit may be taken to be 16kA. However, it's extremely unlikely to see anything near that value unless you like at the side of a substation.

 

[malcolmsanford]

It is extremely unlikely that you really need 25/16mm tails, in a domestic situation how many of us have seen a nice set of 4/6mm tails or I should say 7/036 or 7/044 jogging along nicely for 40 odd years without any sign of burning.

And I'm sure that even if you doubled a Zs value on a protection device it will be extremely unlikely not to trip within it's parameters.

And it is extremely unlikely that someone will get fatally electrocuted in their home........................