Wiring 2Gang 2Way light switches together.

[Negger]

I'm familiar with wiring a single gang 2way light switch and have looked at FAQ wiring diagrams on this site.
To connect 2X 2Gang 2Way switches together, do I simply double up on the standard wiring i.e. run 2X 3core+E between the switches or can I "piggy back" any of the connections.
Obviously I can put a jumper from the live feed between the two gangs in the first switch, but can I "save" any other cores between the switches ?
Both lights are on the same (new) circuit, and both switches operate only a single ceiling pendant light.
A clear wiring diagram would be much appreciated.
If no shortcuts, I will have a twin & E + single core going to each switch (using a jumper) and also 2X 3&E between the switches - Seems an awful lot of wires to squeeze into channel & back boxes !

 

[Space cat]

If you think about what you've got there, the answer should be obvious. You're using a jumper to link live feed across from one switch to the other so you don't need two separate wires to connect those terminals to their equivalents in the other double switch. You can save a core and use a jumper at the other end. In other words, you use 3&E betwen one pair of switches but you only need T&E for the other pair.

The down side to this is that the colours will be wrong and thus potentially confusing. Think about putting some coloured tape on the T&E cores so that they match those in the 3&E.

 

[ban-all-sheds]

It only cuts down on cores though - still need the same number of cables.

If you wire it like the top right one here you can do it with T&E throughout.

//www.diynot.com/wiki/electrics:two-way-lighting#schematic

 

[Negger]

Many Thanks to you both for your input. I can follow the logic of the diagram in the second response & as I have an abundance of T&E & Single core, I'll run with that.
I'll see if I can post a tidy diagram of the overall solution, including junction box, for the benefit of others.
Thank you both again.

 

[bernardgreen]

If you have space in the ceiling area for a junction box then it can be done with just two triple earths to each switch location.

Live to common of one switch ( brown wire ) , L1 (grey) and L2 (black) connected to L1 and L2 on the other switch, grey and black connected (grey to grey and black to black) at the ceiling rose using 2 extre terminal blocks. The common on the second switch ( brown ) brings the switched live to the ceiling rose.

Grey and black sleeved brown,

Second light wired the same way.,

 

[ban-all-sheds]

I have an abundance of T&E & Single core

What is twin & earth & single core cable? Sounds like 3-core & earth.....

 

[ericmark]

I'm familiar with wiring a single gang 2way light switch and have looked at FAQ wiring diagrams on this site.
To connect 2X 2Gang 2Way switches together, do I simply double up on the standard wiring i.e. run 2X 3core+E between the switches or can I "piggy back" any of the connections.
Obviously I can put a jumper from the live feed between the two gangs in the first switch, but can I "save" any other cores between the switches ?
Both lights are on the same (new) circuit, and both switches operate only a single ceiling pendant light.
A clear wiring diagram would be much appreciated.
If no shortcuts, I will have a twin & E + single core going to each switch (using a jumper) and also 2X 3&E between the switches - Seems an awful lot of wires to squeeze into channel & back boxes !

This was at one time common. However there are two major problems.

1) In some configurations you are not running line and neutral on the same route so the impedance of the cable is not correct as a result it can cause radio interference.

2) Where the two lamps are not feed from the same automatic disconnection device (Fuse/MCB) then a borrowed neutral situation can be caused.

What people seem to forget is we are using AC not DC and as a result the feed and return must follow the same route. Although at 50Hz likely you will get away with it at higher frequencies the cable needs matching for example 75 ohm impedance for TV and radio amateurs will use 50 or 300 ohm ribbon cable.

Today we are finding problems with broad band where sloppy wiring can reduce the broad band speed when the light switches are in once configuration. Also cordless phones will be affected.