Re: Re: Twin and Earth Cable Sizes

["Paul Robinson" <ukcueman@xxxxxxx>]

I seem to have unwittingly hijacked this thread. Sorry about that!

Anyway, I will consult my sparky on this. I would much prefer the 6A
breakers to trip before the 32A.If this does turn out to be a problem, I
can
always follow Neil's suggestion and not have the lighting circuit go
through
a breaker in the main consumer unit, or else change the 32A breaker.

Thanks,
Paul


----- Original Message -----
From: "David Buckley" <db@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Thursday, July 03, 2003 1:45 PM
Subject: [ukha_d] Re: Twin and Earth Cable Sizes


>
> The problem with secondary distribution boards is that of
> discrimination, or, how to make sure the 6A mcb in the slave unit
> goes before the mcb in the master unit.  To ensure this happens as
> planned you must either (a) have a massive differential on trip load
> (and 6 vs 32 is not massive), or (b) use a "slower" MCB in
the
> master, so if the slave is all type one, use a type two in the master.
>
> Secondly, earthing - standard T&E has an earth conductor of less
> cross sectional area than the live, and thus you may hav to run an
> earth as well.  I lost track of this bit of the regs.
>
> Thirdly - your real enemies are voltage drop on the link cable, and
> overheating.   Calculate carefully.  Be generous; voltage drop can
> make your lights change intensity as other loads change.
>
>
>
>
> --- In ukha_d@xxxxxxx, "Paul Robinson" <ukcueman@y...>
wrote:
> > 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@p...>
> > 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@b...>
> > > 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@s...>
> > > > 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