Using 15A Fuse wire for a 2.5mm socket radial circuit

[furio85]

I don't normally mess around with the consumer unit but I was hoping someone could help me with this. I have a loft with about 8 sockets, in a radial circuit using 2.5mm. I have the old-type fuse box at the mains where the breakers just have fuse wire.

From what I've gathered its unsafe to use 30A fuse wire and 20A is recommended in this scenario. It seems most places only sell 15A but i'm not sure if that would be sufficient? Any help would be greatly appreciated thank you

 

[EFLImpudence]

You are correct.

Do you have items in the loft that would add up to more than 15A?

 

[Risteard]

You would need to establish the current-carrying capacity of the cable as installed before selecting the protective device. You should also bear in mind that BS 3036 rewireable fuses must be derated by a factor of 0.725 so do not use direct comparison with the current-carrying capacity of the cable and fuse rating.

In essence, for the cable to be protected by a 20A rewireable fuse it must be capable of carrying 20.59A (not including any other potential derating factors to be considered). Also other necessary verification needs to be made.

It could also be argued that altering the protective device rating in essence makes it a new circuit with all the implications of that.

 

[Spark123]

Do you mean 15A fuse in the middle paragraph Risteard?

Furio 85,
Have you just installed it or is it existing?
What sort of fuse box is it?

 

[PBC_1966]

I have the old-type fuse box at the mains where the breakers just have fuse wire.

What type? With some (e.g. Wylex Standard) you can just change out the rewireable carrier for a cartridge fuse or plug-in circuit-breaker.

 

[Risteard]

Do you mean 15A fuse in the middle paragraph Risteard?

Sorry, I did indeed. 27.59A for a 20A rewireable fuse.