I know we have a few electricians here so hopefully someone will give some advice.

I need to fit a meter to a fuse board. The meter needs a low current mains supply of it's own.

To save wasting a 'way' on the board (and so that the tenant can't easily switch the meter off) I was intending to install a fuse holder inside the board to feed the meter.

The fuse will be 2A (or whatever the smallest is that I can get) but will be fed from a 63A incomer.

Does the wire feeding the fuse need to be rated at the full 63A or will >2A suffice?

My thinking is that if >2A is pulled the fuse will go and protect both the wire feeding it and the downstream wire to the meter. On the other hand there could be a situation where the wire feeding the fuse could be shorted and in that case it needs to pass enough current to blow the upstream fuse.

Any advice please?

Chris

[Edited on 29/3/2017 by ChrisW]

Not an electrician but the fuse needs to be smaller than the cable can cope with - so if using a 2amp fuse use a 5amp cable therefore the fuse will always blow before the cable fails.

Sorry not an electrician either but logic says that upstream of the fuse should be rated higher than the 63A incomer fuse in case as you say there is a short in the cable before the 2A fuse.

Cheers
Davie

I would run 10mm cooker cable from the 63 to the 2....

Thanks guys. I had concluded that the feed to the fuse should be >63A but was hoping someone would tell me otherwise.

Chris