new consumer unit 25mm tails

[spark 68]

I might be missing something here (entirely likely) but how does this square with fault current protection, specifically 434.3 and the omission for devices thereof. Didn't think a 100A fuse would protect anything less than 16mm, 80A for 10mm etc. At least that's how I interpreted it when overlaying the adiabatic line for each cable size on the graph of fuse time/current characteristics in the BGB

Hi Julian,

If you read post #8 again, the poster has two caveats,

1) no signs of overheating or deterioration

2) tail lengths of 3m or less (which they have to be anyway)

Point two is using the forward fusing rules 433.2.2 and 434.2.1 amongst others, and whilst not ideal may be acceptable in the circumstances, especially when the tails may typically be less than 1/2m or so, this then uses the OCPD's in the CU to provide the fault protection of the tails.

 

[JulianC]

Ta for that. 434.2.1 covers it. Must have read it a hundred times. And discounted it every time. 2+2=5 :dunce2: