choice of mcb type and ka??

[Adrian80]

hi guys,

i am trying to select the best mcb and rcbo's for my new cu. wylex 15 way split load, dual rcd, high integrity

3 x lights 6 Amp type c 1.5mm t&e
2 x socket 32 Amp type b 2.5mm t&e
1 x fridge 16 amp type b rcbo 2.5mm t&e
1 x loft socket 16 amp type b 2.5mm t&e
1 x shower 50 Amp type b 10mm t&e
1 x cooker 32 amp type b 10mm t&e
1 x alarm 6Amp type b
1 x door bell 6Amp type b
1 x outside flood lighting 6Amp type b 1.5 t&e
1 x garage sockets and lights 16 amp type b 2.5 swa

but the question is 10ka or 6kA mcb's , can anyone explain the difference?

any suggestions about the choices, feel free to comment

 

[GaryMo]

You'll need to measure PFC (highest reading from PEFC and PSSC) to know for sure but 6kA will probably be fine for a domestic CU.

PFC - prospective fault current, the maximum current that will flow under earth fault or short-circuit conditions. Your chosen protective device must be capable of breaking this fault current without damaging the protective device in the process.

 

[RF Lighting]

It depends on you incomming earth and fault loop and neutral impedence.

This can be used to work out the maximum current which will flow in the event of a fault. The MCBs must be rated to at least this value.

Usually 6kA will be sufficient for a domestic supply, but not always.

10kA will somtimes not be enough for some commercial / industrial supplies, but it is unlikely to find a domestic supply which is >10kA

 

[GaryMo]

Where a service cut-out contains a BS1361 type 2 fuse and supplies a consumer unit to BS 5486-13 or BS EN 60439-3 (modern CU) then the short circuit capacity of the overcurrent protective devices in the consumer unit may be taken to be 16kA.