AC Safety Questions

[Bill Layer]

Hi Chris.

The PC-type receptacle you are discussing is known as an IEC connector.
>
>I'm a bit unsure about polarity on the other two prongs, one is marked
>"L" and the other "N".  

L = Line (Black), N= Neutral (White). If the wiring in your house is
correct, Neutral is made common to Ground at the AC Mains breaker box.

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?
>
You are right in fusing the Line side right off the bat; this is the best
method. The onto the switch and xfmr. Other side of xfmr primary is then
common to neutral. 

Polarity is only of (minor) concern with respect to ground leakage current.
Do this test:

Wire the arrangement temporarily, so that the polarity of the xfrm primary
may be changed. Using a CHEATER plug (blow off the ground...), connect the
AC cord to the mains socket. Using a VTVM or DVM, measure AC volts from the
chassis of your power supply to the AC Ground at the socket.

Record the reading, disconnect power, then reverse the xfmr primary and
perform the test again. Record the reading.

Whichever arrangement gave the lowest AC volts reading is more correct.
Wire it that way permanently.

Have fun!

 
Bill Layer
"Heavy old junk wanted"