The safest method is to use a 3 wire plug and carry the ground to one side (or a center tap) of the secondary. Any leakage from the AC to the secondary will be grounded, and a dead short will pop the breaker. This is the industry standard method and the only method I know of that is UL approved except double insulation which some drills use and is not applicable here.
Marshall "M. G. Devour" wrote: > > > The next question is: How can I build in a fuse or > > > breaker to prevent any possibility of my clients (or > > > myself) getting electrocuted in case of accident? > > > > I've never heard of a small AC-DC transformer shorting 120VAC to the > > output; they only die, to my knowledge... > > Would it be too disruptive just to put a resistor in series with the > output as a worst case current limit? Select the value such that it > limits current to a non-lethal value at 120 volts, while only dropping > a little voltage at the design output level. > > Another easy alternative is to put a zener diode "crowbar" circuit on > the output. This consists of a low current fuse in series with one or > both of the supply output leads, and a zener diode connected between > the + and - leads after the fuses. > > This setup causes the fuse(s) to blow if the output voltage exceeds the > zener's reverse bias breakdown voltage, or if the polarity of the > supply should reverse, either of which will cause the zener to conduct. > > Not perfect protection by any means, but cheap. It won't protect > against getting a shock from the line to another object unless your > body conducts enough to blow the fuses. > > Some help from our electrical engineers would be good! > > M. > > [Mike Devour, Citizen, Patriot, Libertarian] > [mdev...@eskimo.com ] > [Speaking only for myself... ] > > -- > The silver-list is a moderated forum for discussion of colloidal silver. > > To join or quit silver-list or silver-digest send an e-mail message to: > silver-list-requ...@eskimo.com -or- silver-digest-requ...@eskimo.com > with the word subscribe or unsubscribe in the SUBJECT line. > > To post, address your message to: silver-list@eskimo.com > Silver-list archive: http://escribe.com/health/thesilverlist/index.html > List maintainer: Mike Devour <mdev...@eskimo.com>
