# Lighting Wiring

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• posted on October 13, 2003, 10:16 am

Dave's keyboard caused the above to slip out into the ethersphere; but what was in Dave's head was to *multiply* by 4 and divide by a thousand. Thus, 1200W pulls 4800/1000 = 4.8A ...
Stefek

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• posted on October 13, 2003, 3:12 pm

I've written out a thousand times 'mustn't post before the coffee kicks in'..
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Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12

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• posted on October 12, 2003, 9:44 pm

It's very simple if we take the ASCII diagram Andy Wade posted, with the intermediate switch removed for simplicity and a couple of alterations:
L1 L1 O===========blue=============O=========== 'Live' \ red wire C O=============red================O C \ O===========yellow===========O=========== Switch return L2 L2 black wire/red sleeve (switched 'live')
Hall Landing Landing switch switch ceiling rose
Now tilt your head to the right so you're looking at the diagram from "top to bottom".
You'll see that the wiring is much simplified over the schematic you suggested. All that is needed is twin core and earth from the landing ceiling rose to the landing switch (i.e. the same as all other lights with single-way switching), and then a short run of three core and earth between the landing and hall switches. The number of wire connections is also minimised - all connections can be made to the back of the switches.
This way of doing it also has the advantage that it's easy to convert any single-way installation to two-way simply by running a length of three-core+earth from the first switch to an additional switch.
Your suggested wiring diagram at <http://www.nthothost.co.uk/assets/imag es/Lighting_circuits_2.gif>, while it would work, would mean running a length of twin+earth from the ceiling rose to each switch, PLUS another length of twin+earth between the switches.
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• posted on October 12, 2003, 9:01 pm
Been following this with interest as I'm about to do the same in the garage.
Is this method OK:
http://www.diydata.com/planning/twowaylight/twowaylight.htm
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Shaun Robertson
Sheffield, UK

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• posted on October 12, 2003, 9:10 pm
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• posted on October 12, 2003, 9:20 pm

Thanks Adam, but is it OK to use the first method there using the junction box? I have two triple 2-way switches so using an external junction box should cut down on the number of wires to each switch. Otherwise I'll need a 6 inch deep pattress box!
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Shaun Robertson
Sheffield, UK

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• posted on October 12, 2003, 9:34 pm
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• posted on October 12, 2003, 10:57 pm

LOL I hadn't noticed that it was marked "5 terminal junction box" but actually had 6!!
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Shaun Robertson
Sheffield, UK

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• posted on October 12, 2003, 9:22 pm

That's the bit that get me as well.

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• posted on October 12, 2003, 11:36 pm

That's historical: in the days when houses were wired with singles in conduit the 'original method', if I can call it that, was used. The alternative method was then only used when converting from one-way switching to two-way.
The original method is still used for conduit wiring where, with correct layout, large current loops can be avoided.
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Andy

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• posted on October 12, 2003, 11:42 pm

I'd add that the way you've called it a ceiling rose or junction box would confuse a newbie as you've laid out the terminals in a way they wouldn't come across. A ceiling rose often confuses the first time, so I'd have shown the terminal layout as it actually exists. And a junction box with the more usual 4 square layout.
You've got to decide what you're aiming for - either a theoretical wiring diagram as Andy supplied, or a practical layout.
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Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12