Everyone who's fiddled with the inside of their computer will be familar
with the four-wire leads that are used to provide power to the hard drives
and CD drives. These leads consist of a yellow wire, a red wire and two
black wires, and terminate in a large white plug.

The yellow wire carries the 12 volt power feed, while the red is the 5 volt.

Because of the rather complicated setup I've got, with three hard drives
running through a drive selector, I've added switches to the 12 volt leads
on two of the drives, so that I can turn them off when they're not needed.

These switches are simple 240v lamp switches - of the push-on, push-off
type.  They have only two terminals, so when the 12v wire is cut, each cut
end is screwed into a terminal socket.

Here's my query:  These switches don't tell me if they are on or off, so
I've bought some 12 volt switches with an inbuilt indicator lamp, the idea
being that, if the switch is on, the lamp will be lit and vice versa.
However, these switches have THREE terminals, and I can't work out how to
set up the wiring. (duh)

The terminals are labelled 'Earth', 'Load' and 'Supply'.  I guess that Load
and Supply would be the two cut ends of the 12v wire, which currently
connect to my simple lamp switch.

But does the Earth terminal need connecting to the chassis?  Or one of the
black neutral wires.  Or what?

Information would be much appreciated.

Ian Porter
Computer Guys Inc.
Arrowtown
New Zealand
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