I seem to recall reading somewhere that in 2 way switching for house lighting its a good idea to have a neutral wire parallel to the lives to cut down on interference, is this so? In which case I need 4 core and earth not 3 core and earth.

I is mentioned at:
http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

[g]

On Wednesday, November 30, 2016 at 11:48:51 AM UTC, DICEGEORGE wrote:
I seem to recall reading somewhere that in 2 way switching for house lighting its a good idea to have a neutral wire parallel to the lives to cut down on interference, is this so? In which case I need 4 core and earth not 3 core and earth.


http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

[g]

http://www.theiet.org/forums/forum/m...threadid=28561
says:

Paul1966

Posts: 1538
Joined: 21 December 2004


The key point is that whatever current flows in one direction along a conductor in a cable should also flow in the opposite direction along another conductor in that cable.

In a single 2C(+E) cable running to a light, the instantaneous current at any moment in L is counteracted by an equal current in N flowing in the opposite direction. In a 2C switch loop, both conductors are live, but the instantaneous current flowing to the switch at any instant in time is balanced by an equal current flowing in the adjacent conductor back from the switch.

This principle just extends to 3C cable and multi-way switching. You might have three conductors in the cable, but for any given combination of switch positions only two will be carrying current, and those currents will be flowing in opposite directions.

DICEGEORGE was thinking very hard :
I seem to recall reading somewhere that in 2 way switching for house lighting
its a good idea to have a neutral wire parallel to the lives to cut down on
interference, is this so? In which case I need 4 core and earth not 3 core
and earth.

I is mentioned at:
http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

[g]

I think you may be looking at the now illegal 'Carter' method. Yes,
interference during switching can be reduced by running 'flow' and
'return' wires in close proximity, but the difference is slight and
light switching is not frequent anyway. Mostly a home will not be wired
with live and neutral co located along their length anyway.

Network and phone cables use twisted pairs and are used as pairs, so as
to avoid interference generation and pickup of interference affecting
the signal. What is picked up (or radiated) by one wire, is cancelled
out by its opposite number.

On 30/11/16 11:48, DICEGEORGE wrote:
I seem to recall reading somewhere that in 2 way switching for house lighting its a good idea to have a neutral wire parallel to the lives to cut down on interference, is this so? In which case I need 4 core and earth not 3 core and earth.

I is mentioned at:
http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

[g]


No. Because your 2 or 3 wires to the switch are already balanced -
current down to the switch = current back up from the switch.

so if 3CE is good enough for 2 way switching
is 4CE ever used in a normal-ish house?

[george]

On 30/11/2016 12:17, DICEGEORGE wrote:
so if 3CE is good enough for 2 way switching
is 4CE ever used in a normal-ish house?

[george]

240v Room Thermostats e.g. Controlling UFH zones

In article ,
DICEGEORGE wrote:
I seem to recall reading somewhere that in 2 way switching for house
lighting its a good idea to have a neutral wire parallel to the lives
to cut down on interference, is this so? In which case I need 4 core and
earth not 3 core and earth.

I is mentioned at: http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

What sort of interference are you talking about?

You might also find it very difficult to obtain 4 core and earth. I've
never seen it in terms of house wiring.

But if it is a problem on a two way switched circuit, it would also be a
problem on the common way to wire lighting with a switch drop from ceiling
rose to switch.

--
*I couldn't repair your brakes, so I made your horn louder *

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

DICEGEORGE wrote:

if 3CE is good enough for 2 way switching
is 4CE ever used in a normal-ish house?

not for lighting, perhaps for heating.

Hmm, cannot see that myself. Without screening and stuff like that switch
impulses will just radiate in my experience.

Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"DICEGEORGE" wrote in message
...
I seem to recall reading somewhere that in 2 way switching for house
lighting its a good idea to have a neutral wire parallel to the lives to
cut down on interference, is this so? In which case I need 4 core and earth
not 3 core and earth.

I is mentioned at:
http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

[g]

With all the incredibly noisy switch mode supplies and powerline internet
adaptors around nowadays, I think most houses need wiring with screened
cables and possibly undeground as well!
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Dave Plowman (News)" wrote in message
...
In article ,
DICEGEORGE wrote:
I seem to recall reading somewhere that in 2 way switching for house
lighting its a good idea to have a neutral wire parallel to the lives
to cut down on interference, is this so? In which case I need 4 core and
earth not 3 core and earth.

I is mentioned at: http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

What sort of interference are you talking about?

You might also find it very difficult to obtain 4 core and earth. I've
never seen it in terms of house wiring.

But if it is a problem on a two way switched circuit, it would also be a
problem on the common way to wire lighting with a switch drop from ceiling
rose to switch.

--
*I couldn't repair your brakes, so I made your horn louder *

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

On 30/11/2016 11:48, DICEGEORGE wrote:
I seem to recall reading somewhere that in 2 way switching for house
lighting its a good idea to have a neutral wire parallel to the
lives to cut down on interference, is this so? In which case I need 4
core and earth not 3 core and earth.

I is mentioned at:
http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

[g]

I have only ever used the "Alternative method of Two Way Switching" on
that page .. adding intermediate when needed

On 30/11/2016 12:17, DICEGEORGE wrote:
so if 3CE is good enough for 2 way switching
is 4CE ever used in a normal-ish house?

[george]


Normal houses ... only 3c+e

In article ,
Brian Gaff wrote:
With all the incredibly noisy switch mode supplies and powerline
internet adaptors around nowadays, I think most houses need wiring with
screened cables and possibly undeground as well!

Why? It doesn't cause a problem here. And I'd guess I have more AV
equipment than most.

--
*For every action, there is an equal and opposite criticism *

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

DICEGEORGE wrote

I seem to recall reading somewhere that in 2 way switching
for house lighting its a good idea to have a neutral wire
parallel to the lives to cut down on interference, is this so?

Nope, its an urban myth.

In which case I need 4 core and earth not 3 core and earth.

Yes, and that is available.

I is mentioned at:
http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

Its bull****.

DICEGEORGE wrote
DICEGEORGE wrote

I seem to recall reading somewhere that in 2 way switching
for house lighting its a good idea to have a neutral wire
parallel to the lives to cut down on interference, is this so?

Nope.

In which case I need 4 core and earth not 3 core and earth.
http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

http://www.theiet.org/forums/forum/m...threadid=28561
says:

Paul1966

Posts: 1538
Joined: 21 December 2004

The key point is that whatever current flows in one direction along a
conductor in a
cable should also flow in the opposite direction along another conductor
in that cable.

That isnt what happens with quite a bit of lighting wiring, and it works
fine anyway.

In a single 2C(+E) cable running to a light, the instantaneous current at
any
moment in L is counteracted by an equal current in N flowing in the
opposite
direction. In a 2C switch loop, both conductors are live, but the
instantaneous
current flowing to the switch at any instant in time is balanced by an
equal
current flowing in the adjacent conductor back from the switch.

Yes, but that doesnt matter with lighting circuits.

This principle just extends to 3C cable and multi-way switching.
You might have three conductors in the cable, but for any given
combination of switch positions only two will be carrying current,
and those currents will be flowing in opposite directions.

Yes, but that doesnt matter with lighting circuits.

Brian Gaff wrote

Hmm, cannot see that myself. Without screening and stuff like that switch
impulses will just radiate in my experience.

Its not clear that he is actually talking about switching transients,
more likely he's just talking about mains frequency hum, but that
doesn’t happen enough to matter with lights.

"DICEGEORGE" wrote in message
...
I seem to recall reading somewhere that in 2 way switching for house
lighting its a good idea to have a neutral wire parallel to the lives to
cut down on interference, is this so? In which case I need 4 core and
earth not 3 core and earth.

I is mentioned at:
http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

[g]

Brian Gaff wrote

With all the incredibly noisy switch mode supplies and powerline internet
adaptors around nowadays, I think most houses need wiring with screened
cables and possibly undeground as well!

No they don’t, most don’t bother with AM radio anymore.

"Dave Plowman (News)" wrote in message
...
In article ,
DICEGEORGE wrote:
I seem to recall reading somewhere that in 2 way switching for house
lighting its a good idea to have a neutral wire parallel to the lives
to cut down on interference, is this so? In which case I need 4 core and
earth not 3 core and earth.

I is mentioned at: http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

What sort of interference are you talking about?

You might also find it very difficult to obtain 4 core and earth. I've
never seen it in terms of house wiring.

But if it is a problem on a two way switched circuit, it would also be a
problem on the common way to wire lighting with a switch drop from
ceiling
rose to switch.

--
*I couldn't repair your brakes, so I made your horn louder *

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