I'm going to reuse a circuitbreaker position that used to power the bell transformer, to provide a dedicated fused connection unit for a new alarm system. The circuitbreaker is 6A, and I'd use a 3A fuse in the FCU, so in theory I can use 1mm lighting cable.
But something is nagging me that I ought to use cable at least enough for a
"keith" wrote | I'm going to reuse a circuitbreaker position that used to | power the bell transformer, to provide a dedicated fused | connection unit for a new alarm system. The circuit | breaker is 6A, and I'd use a 3A fuse in the FCU, so in | theory I can use 1mm lighting cable. | But something is nagging me that I ought to use cable | at least enough for a 13A socket, in case some future | house owner swops the fuses for 13A?
Even if someone swaps the fuse in the FCU for 13A, the circuit is still protected by a 6A MCB. If someone upgrades the MCB then they should take responsibility for ensuring the circuit is suitable.
That said, if you use 2.5mm you are probably okay for up to a 20A radial circuit.
Owain
You are being paranoid - 1mm^2 will be fine. If anyone changes the purpose of the circuit again in the future it's their responsibility to ensure that it's appropriately rated for the new use.
That wouldn't matter, as it is protected at 6A. Indeed, you could swap the
6A MCB with a 3A MCB and not bother with the FCU.Christian.
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