On 14 Jan 2004 09:47:18 -0800,
(Mike Hall) wrote:

The previous householders have re-used a 6mm^2(??) cable, (that I
presume was once used to feed an electric shower), to feed a power
shower pump and the (gas) heating system. (ie. low current draw
compared with the electric shower which I presume it used to feed).
The cable is protected by a 30A fuse in the consumer unit.

In order to make the wiring reach the power shower pump and the
heating system in the airing cupboard, they have extended the 6mm^2
with around 3metres of 2.5mm^2 using a junction box in the loft.

The current situation is clearly unsatisfactory as the 2.5mm^2 is
effectively (incorrectly) protected with a 30A protector.
I understand that the regs say that each reduction in cable size
should be appropriately protected, but I want to know if it is
acceptable just to place smaller fuse at the start of the whole
circuit in the CU. (ie. 16A).
[Working here on the principle that it just becomes a radial circuit
serving less than 50m^2 of floor area].
The alternative, if not, will be for me to replace the 3m of 2.5mm
with 6mm. Not a major issue, but I'm not sure about getting it into
the FCU's, (which incidentally have also been omitted by the previous
'installers')

Either way would be fine, the easiest in your case would be to replace
the 30A fuse with a 16A.
For future reference you can get 6mm into fused spurs, 1 is easy
enough, two are tricky, but do-able with a little effort.


SJW
A.C.S. Ltd.