Ronald Raygun wrote:
harry wrote:

What you have here is the standard method of converting a one way
switched light into a two way.
The one way switch is removed & discarded.
A bit of three-core wire is run from this wsitch postiion to the
additional position.
The commons on the switches are link by one core.
The other two terminals (L1&L2 /"strappers") in the two switches are
linked by the remaining two cores.
The wires that fed te original one way switch are connected toL1&L2
terminals on the switch that replaced the one way switch.
Finish.

That's a very odd "standard method", given that the more orthodox
method requires no more wires. Why the heck wasn't the new 3-core
wire wired as follows instead?

Use two of the cores to connect the two strappers of the two switches.
This is the same as above.

Connect the third core to the common of the remote switch. Then use
the local end of that third core, and the common of the local switch,
as the replacement for the original one way switch.

I.e. either connect the local end of the third core (which is the
common of the remote switch) to the live feed, and then connect the
common of the local switch to the live end of the light bulb, or the
other way round.

Apart from anything else, the circuit is easier to understand.

Though I do see the inherent simplicity of wiring the thing up by
using the three cores to parallel up all three terminals on both
switches.

Because that is how numpties wire switches up.

--
Adam