"Josh" wrote in message
...
On Fri, 06 Nov 2009 18:41:09 GMT, "Joe" wrote:


"Josh" wrote in message
. ..
On Fri, 06 Nov 2009 18:12:08 GMT, "Joe" wrote:

Josh,

How? if you number the terminals on a 4 way as 1 through 4, the hot
ones
are 1 and 3 when the switch is in one position and the hots are 2 and 4
when
the switch is in the other position. There is not one terminal that is
'common'. If there's no common, then you don't have a terminal that
goes
from the switch to the fixture (or, for that matter, there's no common
for
the originating hot). If I'm misunderstanding this, please help me
out.


The 4-way switch just passes through or crosses the wires from one
side to the other, depending on position. Putting 1 and 2 on the top,
and 3 and 4 on the bottom of the switch:

Switch down: 1 - 3, 2 - 4
Switch up: 1 - 4, 2 - 3

So to use as a 3-way, use terminal 1 as common, 3 and 4 for the
travelers, leaving 2 unused

Switch up: 1 - 3
Switch down: 1 - 4

Which is exactly what a 3-way switch does (and you can start from any
of the terminals as common, with the 2 furthest away for the
travelers).

Some diagrams of 3 and 4 way switch wiring:

http://www.ezdiyelectricity.com/?page_id=381

Josh

In every instance in the diagrams you posted, there is no terminal that is
always 'in use' on any of the 4 way switches. There is no common.

In this diagram:
http://ezdiyelectricity.com/images/w...am-600x420.jpg
the terminals (1 & 2 on top, 3 & 4 on bottom), the terminals used are
either
1 and 4 (top left and bottom right), or if the switch is thrown, 2 & 3
(top
right and bottom left). which terminal is the common?



That's because the diagrams are only showing one position of the
switch (crossed); when the switch is in the other position, the switch
connects the top 2 terminals (in that diagram) together, and the
bottom 2 terminals together. That makes any of the terminals common
to the 2 terminals opposite it.

This set of diagrams shows the actual operation of the circuit better:

http://www.wfu.edu/~matthews/misc/sw...WayStills.html

Josh

Josh,

thanks.

jc
"a man is never so sure he's right as he is the moment before he's proven
wrong"