DIY Doctor

2 Way Light Switch Problem

Postby mhordern » Sat Dec 15, 2007 3:54 pm


We want to replace two light switches - one I have done fine - its a 1 gang 2 way with 1 and 2 plus COM.

The other switch (both operate a light in the hall) has no COM just four connections marked 1 to 4.

There are 4 wires connected - one in each two being red and two being blue - the yellow is cut back and insulated - is this a special switch ? and what is in called so I can replace it - or can it be replaced with a standard 2 way switch and if so how should it be wired ?


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Postby rflight » Sat Dec 15, 2007 9:09 pm

:? Not 100% sure about this but if it's one gang then it sounds like an intermediate switch. This is a switch used in between two way switches on a two way circuit. A picture would be good.
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Postby BLAKEY1963 » Sun Dec 16, 2007 10:21 am

rflight is correct martin going by info given !
yes u r correct this sounds like an intermeadiate switch.
to elaborate used to switch a lighting point from 3 positions or
more. ( usually on long corridors or mutiple level buildings )
the 1 - 4 connections switch between L1 and L2 of the strappers
the yellow is being used as the common and remains continous
from one end of the switching arrangement to the other.

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Postby mhordern » Sun Dec 16, 2007 10:36 am


thanks - yes it says its an intermediate switch on the inside - and thinking about it there is another one elsewhere in the houise that switches the light on.

However confusing as sometimes the intermediate has no effect depending on the postion of the other switches.,

I assume there is no way round it and I need to replace it with another intermediate switch ?
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Postby 333rocky333 » Sun Dec 16, 2007 5:53 pm

Should work in any combination of switch positions, may be switch was always connected wrong .

Sounds like your live is at the common of one of the two way switches and the switch live is at the common of the other two way switch,the red and blue are the two way strappers between both two way switches using the L1 and L2 terminals and is why the yellow is not connected .

As others said you also have a intermediate switch, if you remove that intermediate switch and link red to red and also the blue to blue ,try both the two way switches and see if they both now work correct.

If ok look at diagram on back of intermediate switch and reconnect so that red and blue of one cable pair switch across to red and blue of opposite cable pair in one switch position and in other switch position will link from red and blue of one cable pair this time to BLUE and RED of other cable pair.

As in this case both red and blue are being used as switchLIVES wrong connection would just cause switching to work only with certain combinations
Remember to isolate supply first!!
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