AC Safety Questions

[Robert Schrum]

The "L" and "N" are likely "Live" and "Neutral", respectively.  In this case,
you have the fuse/switch on the right side.  In ~117VAC systems in a perfect
world, the neutral wire (white in house wiring convention) is at zero volts or
ground potential.  I've never met a perfect AC outlet, though--there is always
some kind of voltage--sometimes surprisingly high in older homes--between
neutral and ground.  So, never equate neutral for ground, and especially never
tie them together!

The "live" or "hot" wire (black) carries the main ~117 volts.  Putting the fuse
and switch on that side leaves less lesser portion of the circuit at this
potential, should the fuse blow.  (But remember the corollary of Murphy's Law
that says that expensive components will fail in order to protect the fuse. :) )

-----Original Message-----
From: Christopher MacDonald <cmacdon at ix.netcom.com> at hcinternet-server

Sent: Thursday, August 06, 1998 2:03 AM
To: synth-diy at mailhost.bpa.nl at HCINTERNET-SERVER
Subject: AC Safety Questions


Hi all,

In the interest of avoiding electrocuting myself or, worse, someone
else, I would like to describe my intentions for routing the AC supply
into my synth enclosure.  I would appreciate it if those more
experienced than I  could offer advice or at least confirm that I have
made no safety-jeopardizing errors!

I have bought a receptacle for a standard US AC line cord.  This
receptacle is identical to that which one would find on a PC or a
factory synth.  This jack has three prongs, the center of which is earth
(it's marked with an "e" and the "ground" schematic symbol). I intend to
connect this center prong to the ground buss of my power supply and also
to connect the metal enclosure to the PS ground buss.

I'm a bit unsure about polarity on the other two prongs, one is marked
"L" and the other "N".  I intend to connect the prong marked "L" to a
fuse holder and then to my SPST power switch in series, and to connect
that to one lead of the primary power supply transformer coil.  The "N"
prong would connect directly to the other end of the PS primary coil.
Does polarity matter here?

Bad ASCII diagram:

                             \
"L" prong                     \        transformer
<<<------------o^^^^o------o   \o---------o  o------
            fuse holder    switch         )||(
                                          )||(------
"N" prong                                 )||(
<<<---------------------------------------o  o------

(Ground prong connection not shown)

Is this okay overall?  I was planning to use a 1 amp (not slow blow)
fuse. It all seems logical but that hasn't always worked for me in the
past...    :)

Thanks, sorry for more pesky newbie posts.

-Chris MacDonald