I was trying to replace the light fitting in one of the bedrooms today
to a MK Shockguard pendant fitting. When aI remove unscrewed the
exisiting pendant fitting I discovered that there were three twin and
earth cables. The black from two of the cables were connected to the
Neutral of the light fitting. However, the black from other T&E was
wired to the Live. The red wires from all three cables were wired to a
connector block wrapped in electrical insulation tape.

Why has the black been used as Live? Is this cause for concern? Should
I just go ahead and fit the new fitting or should I get an electrican
to take a look at our wiring?

Many thanks!

Distorted Vision wrote:
I was trying to replace the light fitting in one of the bedrooms today
to a MK Shockguard pendant fitting. When aI remove unscrewed the
exisiting pendant fitting I discovered that there were three twin and
earth cables. The black from two of the cables were connected to the
Neutral of the light fitting. However, the black from other T&E was
wired to the Live. The red wires from all three cables were wired to a
connector block wrapped in electrical insulation tape.

Why has the black been used as Live? Is this cause for concern? Should
I just go ahead and fit the new fitting or should I get an electrican
to take a look at our wiring?

This is standard practice for what is known as "loop in" wiring. Nothing
to worry about.

The three cables a

1) power in - probably from the previous light on the circuit (or the
consumer unit if this is the first light)

2) power out: carries power to the next light - will not be there on the
last light in the circuit.

3) Switch cable: carries the live to the switch, and the switched live
from the switch.

Hence 1 and 2 need to be connected together to ensure power continuity.
The neutral to the bulb can also be permanently connected.

The switch wire is unusual in that *both* its wires are live - one
permanent, the other switched. When using red/black (or brown/blue)
cable for this, the neutral coloured wire carrying the switched live
should be marked with tape or sleeving to indicate it is really another
live.

Piccy here (2nd one down)

http://www.diydoctor.org.uk/projects...d_switches.htm



--
Cheers,

John.

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"Distorted Vision" wrote in message
...
I was trying to replace the light fitting in one of the bedrooms today
to a MK Shockguard pendant fitting. When aI remove unscrewed the
exisiting pendant fitting I discovered that there were three twin and
earth cables. The black from two of the cables were connected to the
Neutral of the light fitting. However, the black from other T&E was
wired to the Live. The red wires from all three cables were wired to a
connector block wrapped in electrical insulation tape.

Why has the black been used as Live? Is this cause for concern? Should
I just go ahead and fit the new fitting or should I get an electrican
to take a look at our wiring?

No offence but as you have demonstrated you know nothing about conventional
lighting circuits, I would probably advise the electrician! Everyone has to
learn somwhere though - buy a DIY book that has electrical circuits in and
find out why your installation is the expected one (aside from the lack of a
red sleeve on the black - should be there but almost never is).


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not

In article
,
Distorted Vision wrote:
I was trying to replace the light fitting in one of the bedrooms today
to a MK Shockguard pendant fitting. When aI remove unscrewed the
exisiting pendant fitting I discovered that there were three twin and
earth cables. The black from two of the cables were connected to the
Neutral of the light fitting. However, the black from other T&E was
wired to the Live. The red wires from all three cables were wired to a
connector block wrapped in electrical insulation tape.

Why has the black been used as Live? Is this cause for concern? Should
I just go ahead and fit the new fitting or should I get an electrican
to take a look at our wiring?

Get a bit of paper and draw out the circuit diagram for a light fitting
and switch, grouping the cables together as in TW&E. Include the feed into
the fitting and the one on to the next fitting. It should all then become
clear.

If you're not capable of drawing this out you need to do some very basic
learning before attempting any electrical work of this nature, I'm afraid.

--
*The statement above is false

Dave Plowman London SW
To e-mail, change noise into sound.

Thanks for the replies.

I really don't think I need to pay an electrician just to wire in
pendant fittings when its something I can do easily myself. Yes I
didn't know the neutral coloured wire was switched live but I really
don't think I'd have much of a problem with electricial circuits. I
have a 1st Class MEng degree in Electrical & Electronic
Engineering....not that you learn anything useful like domestic wiring
or lighting circuits of course.

Distorted Vision wrote:

I really don't think I need to pay an electrician just to wire in
pendant fittings when its something I can do easily myself. Yes I
didn't know the neutral coloured wire was switched live

Which one did you think was switched live then?

but I really don't think I'd have much of a problem with electricial
circuits. I have a 1st Class MEng degree in Electrical & Electronic
Engineering

This is the only reason I'm making sarky comments when you apparently do
have a problem with an electrical circuit :-)

Pete

"Distorted Vision" wrote in message
...
Thanks for the replies.

I really don't think I need to pay an electrician just to wire in
pendant fittings when its something I can do easily myself. Yes I
didn't know the neutral coloured wire was switched live but I really
don't think I'd have much of a problem with electricial circuits. I
have a 1st Class MEng degree in Electrical & Electronic
Engineering....not that you learn anything useful like domestic wiring
or lighting circuits of course.

It takes about ten minutes to find out about 99% of domestic wiring.
It is simplified so that semi skilled people can do it.
Getting it to work is easy.
It takes effort and experience to be neat and quick.

In article
,
Distorted Vision wrote:
I really don't think I need to pay an electrician just to wire in
pendant fittings when its something I can do easily myself.

But you couldn't?

Yes I didn't know the neutral coloured wire was switched live but I
really don't think I'd have much of a problem with electricial circuits.

Patently you do. When faced with something like this that you don't
understand the normal approach would be to draw out the circuit diagram.

I have a 1st Class MEng degree in Electrical & Electronic
Engineering....not that you learn anything useful like domestic wiring
or lighting circuits of course.

And this didn't involve drawing and following circuit diagrams?

--
*Proofread carefully to see if you any words out or mispeld something *

Dave Plowman London SW
To e-mail, change noise into sound.

But you couldn't?

Yes could and I did this morning. I just wanted to ask why the black
was live that's all.

Patently you do. When faced with something like this that you don't
understand the normal approach would be to draw out the circuit diagram.

Well I don't want to get into an argument over it but yes after
drawing the circuit diagrams its clear how simple it is.

I have a 1st Class MEng degree in Electrical & Electronic
Engineering....not that you learn anything useful like domestic wiring
or lighting circuits of course.

And this didn't involve drawing and following circuit diagrams?

Well yes obviously, right up to advanced circuit analysis and
theory.

Distorted Vision wrote:
But you couldn't?

Yes could and I did this morning. I just wanted to ask why the black
was live that's all.

Patently you do. When faced with something like this that you don't
understand the normal approach would be to draw out the circuit diagram.

Well I don't want to get into an argument over it but yes after
drawing the circuit diagrams its clear how simple it is.

I have a 1st Class MEng degree in Electrical & Electronic
Engineering....not that you learn anything useful like domestic wiring
or lighting circuits of course.

And this didn't involve drawing and following circuit diagrams?

Well yes obviously, right up to advanced circuit analysis and
theory.


Please don't tell us that your day job involves anything that might
impinge on public safety. ;-)

On Wed, 11 Feb 2009 19:24:28 -0800 (PST), Distorted Vision
wrote:

I was trying to replace the light fitting in one of the bedrooms today
to a MK Shockguard pendant fitting. When aI remove unscrewed the
exisiting pendant fitting I discovered that there were three twin and
earth cables. The black from two of the cables were connected to the
Neutral of the light fitting. However, the black from other T&E was
wired to the Live. The red wires from all three cables were wired to a
connector block wrapped in electrical insulation tape.

Why has the black been used as Live? Is this cause for concern? Should
I just go ahead and fit the new fitting or should I get an electrican
to take a look at our wiring?

Many thanks!

Who is al remove ? :-)