Re: Twin and Earth Cable Sizes

["Neil Fuller" <neil@xxxxxxx>]

>>First the disclaimer: I am not an electrician.

I am an Electrician!!!!!

>>The size of the cable to feed your secondary board would depend on
the load
the cable would take

True - Up to a point (see below)

>>My lighting will be fed from a single circuit on the
consumer unit via a 6mm cable and protected by a 32A MCB

That's fine but you could also feed the second board straight from the head
using a 'junction box' specifically made for the purpose - A Service Block
(TLC order code MK1100) This would save a valuable way in the main consumer
unit. The size of cable used would depend on the head fuse - 25mm or 35mm
'tails'  (double insulated, single core, stranded cables) are normal.


>> The 32A figure is because every light turned on at 100% (which
won't happen
in practice) will use a little below 32A.

The 'Won't happen in practice' is allowed for in the 'Regs' - It's known as
diversity. For instance, using your 'equation' you could only have 2 single
13 amp sockets on a 32amp sub-circuit if diversity wasn't allowed. In
practice, you can have as many 13 amp sockets as you wish as it is
recognised that many loads only take mA at 230v.

My copy of the 'regs' is at work so I can't quote actual figures. If you
really want to know, I'll look it up...

One other thing ref the lighting circuit in 2.5mm question. You need to
consider what your actual loads will be before you opt for 1 or 1.5mm2
cable. For instance, if you are running a circuit for several out door,
500w floods, you will almost certainly need to run it in 1.5mm. If it's a
few 60w incandescent lamps them 1.00mm will be OK

Finally, a non PC joke - How many dyslexics does it take to change a light
blub!!!

Finally, finally - Don't forget the earthing on the new consumer unit. Many
do!

HTH

Regards

Neil

----- Original Message -----
From: Paul Robinson
To: ukha_d@xxxxxxx
Sent: Wednesday, July 02, 2003 6:18 PM
Subject: Re: [ukha_d] Twin and Earth Cable Sizes


First the disclaimer: I am not an electrician.

The size of the cable to feed your secondary board would depend on the load
the cable would take. My lighting will be fed from a single circuit on the
consumer unit via a 6mm cable and protected by a 32A MCB. That goes to a
secondary board which will have 6 10A MCBs, one per 4/8-channel dimmer.

The 32A figure is because every light turned on at 100% (which won't happen
in practice) will use a little below 32A.

If your secondary board was going to use much less power, then you could
use
a smaller cable. And vice-versa.

HTH
Paul

----- Original Message -----
From: "wayne" <wayne@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Wednesday, July 02, 2003 6:06 PM
Subject: Re: [ukha_d] Twin and Earth Cable Sizes


> Ok, just jumping on this thread, If I wanted to add a 2nd distribution
board
> to an existing - what size do you use there?
>
> Thanks
>
> Wayne.
>
>
> ----- Original Message -----
> From: "Jon Payne" <jgpayne@xxxxxxx>
> To: <ukha_d@xxxxxxx>
> Sent: Wednesday, July 02, 2003 4:06 PM
> Subject: Re: [ukha_d] Twin and Earth Cable Sizes
>
>
> > I'd agreed with James. I did this initially and it can get a real
pain
in
> > the a*** working this 2.5mm cable everywhere. 1.5mm is so much
easier to
> > work with - get some :)
> >
> > Jon
> > ----- Original Message -----
> > From: "James Hoye" <james.hoye@xxxxxxx>
> > To: <ukha_d@xxxxxxx>
> > Sent: Wednesday, July 02, 2003 3:04 PM
> > Subject: RE: [ukha_d] Twin and Earth Cable Sizes
> >
> >
> > > > I have a simple question, If i am doing some wiring in
lighting
> > > > circuits is it OK to use 2.5 mm Twin and Earth? It
would save me
> having
> > > > to buy 2 different types of cable, as I know 2.5mm can
be used for
> > > > power circuits (sockets) etc.
> > >
> > > >From an electrical safety point of view I can't see any
issues -
2.5mm
> is
> > > certainly capable of carrying a 5 or 6A load!!!
> > >
> > > What may be a problem is coaxing the larger size cable into
terminals
> > meant
> > > for 1.0/1.5mm cables - oh, and it might well confuse any
person doing
> any
> > > electrical work in the future.
> > >
> > > A 100m roll of 1.5mm T&E is only ?11.99 from Screwfix
[other suppliers
> are
> > > available etc]
> > >
> > > James H