RE: Wiring LW11G

["Nikola Kasic" <nikola@xxxxxxx>]

Hi Neil,
I can contact you directly, but I think your opinion will be interesting
for
other members of the group.
Why do you think regulations require that all cables have an earth
conductor, if that conductor is not going to be connected?
I don't see the logic, so you might have an idea because you were dealing
with all kinds of scenarios. All my switch dry lining boxes are plastic and
earth conductor is not connected to anything. Just insulated so it doesn't
touch anything. Fortunately, it's not cut short, but left long, so I can
use
it.

I can understand if I have switches with metal plate. In that case, that
plate needs to be earthed, to prevent Live coming to metal surface in any
scenario.

However, all my switches are plastic (MK type) and have no terminal for
earth wire. Nor LW11Gs have, so I have one unused wire in the cable, which
regulations say I shouldn't use.
I understand that you didn't write regulations, so I don't blame you ;-), I
am just trying to understand the logic.
Wire diameter is the same for all three wires, so that's not a problem.

BTW,
Do you know LW11Gs? Do you know if there is any current going through that
neutral wire?
I thought that current is coming in the Live terminal and exiting at
Switched live, when switch is on. So I'm not sure what that neutral is for.
It must be something with dimmer.

Cheers,
Nik
-----Original Message-----
From: Neil Fuller [mailto:neil@xxxxxxx]
Sent: 24 February 2003 19:23
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] Wiring LW11G


Hi Nik

Wow - Those diagrams must have taken ages!!

I can see exactly what you have done. From an electrical safety point of
view, it is certainly much better than your previous job.

Electrically, it's safe enough, though it certainly is not to current
regulations which basically stipulates that all cables should have an earth
conductor. There are exceptions (such as flexible leads to double insulated
appliances).

That said, it was only recently (well, about 30 years ago now!) that
lighting circuits required an earth conductor.

So, to sum up, electrically, it looks safe enough, as long as the switches
are double insulated with no exposed metal etc. It is not to the lastest
wiring regulations and therefore, cannot be condoned. . . . . . . .

It's a bit of fence sitting but professionally, I cannot give it a clean
bill of health.

I hope you understand what I am trying to say.

If you want any further help, Email me directly and we can talk.

Regards

Neil


----- Original Message -----
From: Nikola Kasic
To: ukha_d@xxxxxxx
Sent: Monday, February 24, 2003 11:50 AM
Subject: RE: [ukha_d] Wiring LW11G


Hi Neil,
Thanks for jumping in with explanations.
I discovered that ELCB is not connected to lighting circuits, so I
became worried and already started labeling and doing work.
Can you please confirm that what I'm doing is O.K.?
I have only 3 LW11Gs so far (one is enough to kill you, though).
LW11Gs are all controlling ceiling lights, they are dimmers, so no
appliances are connected there. Metal parts of the lights are earthed
with earth wire.
Original wiring is like this:
I have plasterboard walls and plastic dry lining boxes. The wires go
>from
There, they are distributed via 3-wire cable (red, black and naked (with
green/yellow sleeve attached on top)).
One cable goes from distribution box to wall switch. The other goes to
light.
The one going to switch carries Live (red wire), connects to switch and
>from
back to distribution box. It's there connected to cable going to light.
Switched Live is now red wire with black tape going to light and via
black wire current is coming back to Neutral in distribution box.
Circuit is in that way closed.
This is my attempt to make ASCII drawing of the diagram

Dist. box
Live (red)             _________    red
--------------------------+------------------------------
Neutral (black)                   black (red tape)       \  switch
-----------------------+     +---------------------------

-------------------------+-----------------------------   not
connected
Earth                 ______


black     red (black tape)
-
--O--
light


The earth wire going from dist. box to dry lining switch box is not
connected in the switch box, because the box is plastic one and switch
doesn't have earth terminal, so it's just terminated with connection
block.

What I did is, I just used three wires in switch dry lining box for
connecting LW11G, so it looks like this:

Dist. box                              LW11G
Live (red)             _________    red                     _______
--------------------------+------------------------------L---
Neutral (black)                   black (red tape)           \
-----------------------+     +---------------------------SL--

-------------------------+-----------------------------N
Earth                 ______                          _______


black     red (black tape)
-
--O--
light

As we discussed earlier, this is not correct wiring, so I am now doing
it this way:


Dist. box                              LW11G
Live (red)             _________    red                     _______
--------------------------+------------------------------L---
Neutral (black)                   black (red tape)           \
-----------------------+---+ +---------------------------SL--

------------------------+ +----------------------------N
Earth                 ____ _                          _______


black     red (black tape)
-
--O--
light

I am now using green/yellow wire from dist box to switch dry lining box
to carry neutral. I'll put a black tape on green/yellow sleeve on both
ends to indicate that it's not earth any more but neutral.

Do you think that this is O.K. now, according to regulations etc.?

I have no way to insert extra wire (except by ripping off the
plasterboards).

Cheers,
Nik

-----Original Message-----
From: Neil Fuller [mailto:neil@xxxxxxx]
Sent: 23 February 2003 11:19
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] Wiring LW11G


Nik

As an Electrical Engineer, I've watched this thread develop "with
interest"!

Your latest post has made me decide that it's time for me to chuck my
threepennyworth in too . . . .

The earth connection both within cables and, more importantly, at
appliances, is there for a reason.

If you go ahead with this, it means that your cables and appliances do
not have an earth connection. It could be argued that the Earth and
Neutral are at (more or less) the same potential as they are connected
to the star point at the sub station transformer, so it makes no
difference. However, the earth connection at appliances is important to
protect against short circuit failures to enable rapid disconnection via
the fuse or trip and thus prevent the cable or appliance overheating and
potentially bursting in to flames.

Having actually witnessed someone getting a fatal shock due to poor
earthing on an appliance, I strongly urge you NOT to do this. The chap
in question was a scene hand on a film I was working on several years
ago. He died instantly. He left a wife and 2 young children.

In the event of a fire or someone getting a _fatal shock_, don't admit
to your _bodge_ otherwise the insurance company are unlikely to pay out.

Also, removing the earth from some appliances is likely to result in
radiated and conducted RFI (Electrical Noise) - something that you
certainly don't want with X10 or similar appliances.

I am in a similar situation here and I have decided that the only option
is to rewire the switch drops. A pain in the botty but at least it's a
"proper job".

As Phil said, "DIY'ers have a reputation for bodging things and doing
a
half assed job - please don't reinforce that reputation!"

Think very carefully before you go ahead with this Nik.

Regards

Neil
----- Original Message -----
From: Nikola Kasic
To: ukha_d@xxxxxxx
Sent: Saturday, February 22, 2003 1:01 PM
Subject: RE: [ukha_d] Wiring LW11G


O.K.
You convinced me. But that means that I'll have to use green/yellow
sleeved
wire as a neutral, which is even more likely to cause confusion. I'll
tape
it with black tape. Also, it's not perfectly insulated (uses sleeve)
so if
it touches something grounded, I'm in the same situation. Or if it
touches
metal switch box.
Nik
-----Original Message-----
From: Phil Harris [mailto:phil@xxxxxxx]
Sent: 22 February 2003 08:49
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] Wiring LW11G



Exactly Frank,

Just because "it works" doesn't mean it's right or you should do
it.
DIY'ers
have a reputation for bodging things and doing a half assed job -
please
don't reinforce that reputation!

Phil

> -----Original Message-----
> From: Frank Mc Alinden [mailto:armagh@xxxxxxx]
> Sent: 22 February 2003 01:49
> To: ukha_d@xxxxxxx
> Subject: Re: [ukha_d] Wiring LW11G
>
>
> Nik
>         Do yourself a big favour and give it some more
thought....If the
> earth you are using as a neutral is connected to the earth bar on
your
> switchboard and some one works on it while the lights are on they
will
> certainly get a shock if they disconnect the earth wire.......and
> as i said
> before if you loose your main earth ..every thing that is earthed
may
rise
> above ground potential.....a very dangerous
situation.........Everything
> will work fine BUT if something goes wrong it could  be
> fatal......................
>
>
> Frank
>
>
>
> ----- Original Message -----
> From: "Nikola Kasic" <nikola@xxxxxxx>
> To: <ukha_d@xxxxxxx>
> Sent: Friday, February 21, 2003 9:46 PM
> Subject: RE: [ukha_d] Wiring LW11G
>
>
> > I thought a bit more about it and I don't really see it a big
issue.
> > Earth wire is normally naked in the cable, but but there is a
> > yellow/green sleeve put on it everywhere.
> > Current comes from the Live wire on the LW11G and goes out via
Switched
> > Live towards the light bulb and from light bulb via neutral
closes the
> > circuit.
> > There is no current going through neutral wire (which I changed
with
> > ground wire) connected to LW11.
> > If there is some current going that way, it would cause ELCB to
trip,
> > which is not happening, or the current going through it is very,
very
> > small.
> > ELCB works in a way that it checks the current coming from Live
and
the
> > current returning through Neutral. If there is any difference,
it
trips,
> > because that means that current it dissappearing somewhere
(earth
> > leakeage). Either via Earth wire, or via someones's body to
earth
> > (that's more worrying).
> > Ground and neutral are bonded anyway, not in your flat, but in
the
> > substation.
> > I'm not sure, therefore, what is that Neutral wire used for in
LW11.
> > Cheers,
> > Nik
> >
> > -----Original Message-----
> > From: Phil Harris [mailto:phil@xxxxxxx]
> > Sent: 20 February 2003 22:30
> > To: ukha_d@xxxxxxx
> > Subject: RE: [ukha_d] Wiring LW11G
> >
> >
> >
> > > I must admit to doing this when im commissioning a machine
when
> > theres no
> > > neutral at the 3 phase outlets ..but its only temperory
job.....
> > > If for some reason you loose the main earth it could mean
that
> > > all earthed
> > > equipment will become live when the light is turned
on..........not
a
> > > pleasent thought...........
> >
> > Absolutely correct if you still have the "earth"
conductor still
tied
to
> > earth but that won't happen if you have moved it over and tied
it to
> > neutral...
> >
> > ...but hopefully the fact that Frank and I are basically
spending four
> > or
> > five emails just clarifying exactly what we mean gives you a
bloody
good
> > idea of *WHY YOU SHOULDN'T DO THAT KIND OF THING!!!!*
> >
> > Phil
> >
> >
> >
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