On Sun, 26 Aug 2012 12:24:02 +0100, Dave Liquorice
wrote:

With three switches the load has to be on the other side of the "supply"
change over switch. With four or more switches the load can be any where
except on the last change over switch. I think...

In the general case there is a 2-way switch at each end with any number of
intermediate switches in between. You can connect the load(s) and supply
to any leg, including the end ones (my drawing shows the load and supply
connected at the left-hand end). But the load must be connected to the
same leg as the supply!

One way to think about it is that a changeover switch plus any number of
intermediate switches is equivalent to a single changeover switch. This
allows you to expand the basic topology as shown on Wikipedia by adding
intermediate switches at either end:

Changeover switch (plus any number of intermediate switches)
load(s) + supply
Changeover switch (plus any number of intermediate switches)

Richard.
http://www.rtrussell.co.uk/