| I would still like to know if someone knows what is the actual function of | the neutral connection.
With respect to the X10 switch it is either/both to power the switch and to let the switch see the full amplitude of the X10 control signal. Two- wire (no-neutral) switches get both through the load, a trick that does not work well for some kind of loads.
| While your statement is almost always true, note | that very low current devices such as lighted switches do use the ground to | complete the circuit. They do not even have a neutral terminal.
This was true at one time, but probably not in the way you meant. Conventional lighted toggle switches have their lamp in series with the load (i.e., across the switch). They do not use ground for anything other than to ground the frame. Some of the LED-illuminated PCS/Lightolier slave switches did ship with instructions that said you could connect the grey(?) return for the LED power to ground if there was no neutral in the box. This surprised me since I thought this practice had been forbidden for a long time (decades?) before such switches even existed. In any case, the instructions no longer say this.
I suppose you could argue that some fluorescent fixtures use the ground for more than safety since they will not start correctly unless the reflector is grounded. But this is more of a bug than a feature. :)
| Is the | mechanism in an X-10 switch analogous to the lighted switch or does it use | more than a trickle current?
In most cases it uses more current than any of the devices that might at one time have been allowed to use the ground, and in any case such use is certainly now forbidden. The requirement for AFCI breakers on all circuits (with AFCI breakers including some level of ground fault detection) should put the final nail in the coffin.
Dan Lanciani ddl@danlan.*com