FCUs as circuit protection for part of circuit

[Dunc]

I'm sure we've all come across these scenarios:

16A supply to garage from consumer unit to a socket and an FCU feeding the lights with a 5A BS1362 fuse.

32A ringmain extended to feed conservatory with FCU with 3A BS1362 fuse feeding garden/patio lighting.

Central heating supply from ringmain or dedicated 16A circuit, all controls fed in 1mm PVC-PVC flat cable via FCU with 3A BS1362 fuse.

Now my question is, how do you go about doing the testing and recording the results on a minor works certificate considering the FCU alters the supply characteristics of the final circuit. Do you provide separate R1+R2 and Zs reading for everything after the FCU, do you test to the furthest point on the circuit and record it as if the FCU doesn't exist or do you just test at the FCU as though that is the final point and disregard everything there after. Or, do you do something else entirely?

Would be interested to know what you do.

 

[Deleted member 26818]

I would list it over two lines.
Garage lights up to FCU.
Garage lights from FCU.

 

[malcolmsanford]

Agree with spin there I would note it as a sub circuit within a circuit and over 2 lines.

Of course if your Ring final is RCD/RCBO protected and the spur is just a normal FCU then really the FCU EFLI for that 1362 fuse is pretty much negated, and would just enter 1667 in the appropiate box. The 3amp 1362 is just there for overload protection on that sub circuit.

If it was the other way round the FCU was RCD protected and the ring final was BS 3036 or MCB protected then I would enter over 2 lines the recorded Zs value for the ring final and then 1667 for the sub circuit.