1 set of LED's not working

[Twin Dad]

Suggests that the two way switch is ok and that dimmer possibly not.

Personally I would ISOLATE power, NOTE the dimmer wiring and disconnect, use a connecter block to join together the wires taken from L and common,
Park the wire from L1 safely in a connecter block
Reset the power and the lights should hopefully work as one way from the other 2 way switch, until you can sort out a dimmer if needbe

EDIT as switch has common, L and L1
Rather than common, L1 and L2 sorry

OK, Common and L together, with L1 tucked away. The 2nd switch now controls the spots in question which come on as they should........ A new dimmer needed me thinks.......

For future reference/understanding, would I get the same effect with L1 and common together? Just with the 2nd switch operating on/off in the opposite position?

Many thanks to all for your help.

 

[EFLImpudence]

Yes.

If you connected all three together, the lights would be on permanently and the other switch would have no effect.

 

[333rocky333]

As above, Yes, The supply feed is actually at your other switch common.

The supply then comes down either L or L1 to your dimmer switch, dependant how the other normal switch position is.

The actual Lights are connected to the COMMON on the dimmer.
Therefore the electric to your lights goes via dimmer L to common or via dimmer L1 to common, hence why you needed to cap L1 safely

When you voltage tested across your switch, you bridged your faulty switch, hence the 240 volt reading,
You was reading Live from L or L1 and the meter was picking up the neutral via the common, the cable to the light, via the lamp and hence back to the Neutral connection

This I think, I may be wrong, could damage some cheap multimeters as you are putting the load of 6 lights possibly through the meter.

I think what Terryplumb may have meant by "testing voltage across the switch" was testing Common, L and L1 to EARTH or if a Neutral at the switch, Common, L and L1 To Neutral,
As reading 240 volt that way from the common on the dimmer would as he implied" rule out a faulty dimmer"

There are various other ways to wire 2 way and also switch labelling can vary as you will likely find on your new dimmer.

The main types are

Common with L L1
Common with L1 L2
1 with 2 3
L1 with L2 L3

 

[terryplumb]

sorry for the confusion re : "voltages across switch " . worded very badly.!! 333 rocky333 has explained it very well in post above ,cheers for that . glad you got sorted diyoliver .regards terry.

 

[Twin Dad]

Thank you both for the time you have taken to answer here, and to explain in so much detail. Much appreciated.