Neutral terminal on X-10 type wall switch

I would still like to know if someone knows what is the actual function of the neutral connection. 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. Is the mechanism in an X-10 switch analogous to the lighted switch or does it use more than a trickle current?

X-10 wall switches for fluorescent fixtures usually contain a relay and as such need a "real power" connection for the relay coil. You can usually hear a click whenever these switches turn on or off.

You can NEVER safely use a ground connection for a neutral.

The neutral wire is there to complete the circuit back to the breaker panel. It is sized the same as the hot leg and must carry the same amount of current.

Not if the installer follows code, they don't. The ground is for safety, not to be used as a current carrying conductor. It is not sized for the purpose either. For example, you may have multiple circuits supplied through 14 AWG cable using a single, 14-gauge ground wire.

Switch legs sometimes have only hot, switched hot and ground leads. This is common where power is supplied directly to a fixture or outlet. In such cases the neutral is not required but that does not mean that the safety ground can be used in the manner you would like.

Don't get us wrong on this, friend. No one here is trying to be a code enforcer. We're only telling you what we've had to deal with on our own installations.

"Marilyn & Bob" wrote in news:_YKni.10414$yx4.9624@trndny08:

Lighted switches do NOT use the ground to complete the circuit. They complete the circuit through the load. They operate with such a low current that the load is not visibly affected.

To demonstrate this, take a properly wired lighted switch and remove all of the loads (bulbs) from the circuit. The light in the switch will no longer work. If the light in the switch still works, either you missed a load or the wiring is incorrect.

| 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

Thank you this is the anwer that I wanted as it was the expanation (as opposed to admonition) that I was looking for.

I did this experiment and the light stayed on when the switch was in the open (off) position. I removed all the bulbs, even though they are CFs and there would be no current through the load when they were off in any case.

The switch is a standard lighted SPST wall switch. It is connected to the line and load. Ground is through the box (BX cable). When the switch is wired but out of the box (and the breaker is ON), the light does not go on. The circuit is unquestionably completed through the ground. If you have a lighted switch, I suggest you do your experiment.

A later poster indicated that the fluorescent light switch uses the current to trigger a relay and so it is more than a trickle and thus it is not the equivalent of the lighted switch and requires an actual neutral connection.

"Marilyn & Bob" wrote in news:m77oi.22$Nf4.7@trndny08:

I disagree. As described in this newsgroup previously, CF lamps have electronic sircuitry that can conduct current even when there is insufficient current to light the flourescent bulb. I would call this an incomplete test, except for your next comment:

Since you tried both grounded and ungrounded and got different results, I will admit that this was a good test. I am AMAZED. This implies that (with the breaker on) the frame of the switch is hot (although the amount of current available may be limited by a high value resistor). It is a poor practice as far as I am concerned.

I have tried the experiment with my own "standard lighted SPST wall switch" with very different results. Grounded or not does not matter. Only the presence or absence of a load in the cirucit (and the state of the switch and breaker) determines whether the light is on or not.

Your answer brings up one (hopefully) last question: if CF bulbs normally carry a tiny bit of current when the switch is off, but the breaker on, why can they not be turned on and off by a standard X-10 switch? As I said previously, my standard X-10 switch works fine controlling 5 lamps in parallel (track lights) with 4 being CFs and one incandescent, but won't work if all five are CFs.

"Marilyn & Bob" wrote in news:ORMpi.2100$Ok5.1102@trndny02:

X-10 switches without a neutral connection are specified to require a minimum load (of about 40 W if I recall correctly). Basically this means that the resistance of the load has to be sufficiently low so that the X-10 transmitter can get sufficient signal through the load to the receiver (switch). A CF bulb (or even five in parallel) does not have a low enough resistance (equivalently, does not pass sufficient current) to pass a sufficient signal through from transmitter to receiver.

Solutions include

1) Provide an alternate path, such as an incandescent bulb in parallel as you did. You may find that something less than 40 W is sufficient. 2) Use an X-10 switch rated for use with flourescent lights - it will have a neutral connection. In this case, the signal amplitude seen by the switch is mostly independent of the load. Such a switch should work even with one CF bulb.

Good luck!