3 way light switching without an intermediate switch ??

Would someone like to tell me how it's done?

On the Wiki 2w diagram below could you cable and run a switch from the 1st switch position (RHS of picture) as a mirror image of the switch on the LHS .

Thus the switching method of the LHS would be duplicated from the RHS switch in the 3rd switch position ?



If not this way then how do people do a 3 way switching without using an intermediate?

Reason I ask is that I have recently done 3 way switching using MK grid switches to allow for a 2 gang switch doing 1 way and 3 way switching using intermediate 20a grid switch.

This makes the house non standard since all other switches are vanilla MK with this one exception.

I ripped out the old 3w switching (silly lad) without checking the method used, but the switches were all standard 2 way with L1, L2 and C.

Come on, dish the dirt and please explain the 'cheat'

You must be mistaken

One of them will have been an intermediate.

It's not possible to acheive 3 way switching without one.

short of using relays you cannot do three way switching without using an intermediate switch.

plugwash said:

short of using relays you cannot do three way switching without using an intermediate switch.

Click to expand...

You can do it with two 2way switches side by side and operated together...

one pair of strappers to the two commons.

of the other pair one to the two L1s and the other to both L2s

If both switches are up or both are down it works. (with some makes of switch the L1 and L2 on one switch may need to be changed over )

This old chestnut just keeps on turning up. Plugwash and RF Lighting are correct; true 3-way switching cannot be done with three 2-way switches alone. An intermediate switch has four terminals, two in and two out. It either passes the connections straight through or crosses them over when you flip the switch. Multi-way switching can be achieved by adding extra intermediate switches.

On the Wiki 2w diagram below could you cable and run a switch from the 1st switch position (RHS of picture) as a mirror image of the switch on the LHS?

Click to expand...

If you do this you will find that the three switches work in a rather strange way. If the light is OFF, any of them will switch it ON but BOTH of the other switches will have to be flipped to turn it OFF again. To make it work without an intermediate switch you will need a relay.

If you must use a particular style of switch that isn't available as an intermediate in a particular location, you could cable that switch as either the first or last, and cable other switches as intermediates

Assuming this is a follow on from your question last week, is there any particular reason that you have to use MK?

TLC stock an MK Logic switch - Ref MK K4875.
You can also get an MK switch from Screwfix.

Is this what you are looking for?

No, I was certain there was no intermediate switch on the old 3w set up.

Being a sad muppet I spent half an hour going through all the old fittings taken off over the process of the full rewire.

Guess what? I was wrong, there was an intermediate switch on the old set up, what through me was that it was up on the 1st floor landing and in the most illogical of position as the intermediate.

So thanks guys, sorry that the post might have suggested I was a doubting thomas

As mentioned, the new wiring was fine after I followed Spacecats advice and bought the grid switch bits.

Thank you all