"Mike" wrote in message
...
On Mon, 15 Dec 2008 20:20:51 GMT, "ARWadsworth"
wrote:


"Mike" wrote in message
.. .
On Mon, 15 Dec 2008 06:49:57 -0800 (PST), JohnW
wrote:

I have a Wylex Consumer unit with rewireable fuses. The cooker fuse is
30A (Red) which I need to change to 15A (Blue). Do I have to change
the backplate as well as the fuse, as the cable is still rated at 30A
so the 30A fuse could safely be reinstated for a future appliance (6mm
cable).

What do you really think the consumer unit fuse / MCB is protecting?
It's almost never ever the appliance, it's the cable.

Leave the 30A fuse in there with the existing cable and even if you
installed a cooker with no heating elements and just a 15W light in
the oven space then your installation is safe and adequately
protected.


That sounds about as safe as letting Gary Glitter babysit the kids with
Micheal Jackson supplying the entertainment and Beverley Allitt acting as
the nursemaid with Sharon Shoesmith overseeing it all in case things go
wrong.

But it is completely safe. Do you suddenly decide to fit a smaller
MCB or fuse on a ring main when because of the credit crunch you stop
using a 3 bar electric fire to keep warm and sit instead round a 15W
candle lamp plugged into a 13A socket outlet for warmth?

The plug fuse protects the cable to the lamp, the fuse or MCB at the
consumer unit protects the fixed wiring.

A 30A fuse or MCB fitted in a consumer unit, on a circuit such as a
cooker circuit using cable originally sized for carrying that load is
safe with a load of 30A (and beyond) or without any load or with any
load between those values.

What if you fit a gas cooker and for some ambient lighting in the
kitchen you plug a able lamp into the socket on the cooker outlet
unit. Does that installation, fuse/MCB cable etc suddenly become
unsafe? (assume the lampshade is nowhere near the gas flame!)

For f*cks sake calling someone to back me up on this! Am I right or
am I completely mad?


Mike

You have added an extra socket and fused plug to your reply that was not on
your original post:-)

There is nothing wrong with a 30 amp fuse supplying 6mm T&E to a single
socket and then using the single socket to supply a 15W light using a 3A
plug or something similar.

I knew what you meant on your OP but you did not say it. I am frequently
guilty of doing that as well.

Adam