Lights turning extra modules on and they cannot be turned off

[criskolo]

Is it possible that you wired the XPT module to the SAME black and white wires as the switch right next to it?
This is my case, I did connect the black and white wires to an x10 switch in the same gang box. If the switch light is OFF, the XPT works just fine turning on and off and dimming all other lights. But if the other switch is ON, XPT stops working until I turn the other switch OFF. Is this normal? How can I solve this if I don't have an extra set of black & white wires (it used to be a 3 way switch without the neutral)

[Brian H]

criskolo; Sounds like you connected your XPT to a switch loop. Where the Line is on one of the switches contacts and the other is the lights line input. The White in that case is NOT neutral. So when the manual switch is off. The XPT steals its power return through the load; back to the real Neutral. When the manual switch is on. There is no power on the XPT as it is being shorted out by the manual switch.
So a White wire is no guarantee it is a Neutral.

I have a few switch loops in my home and yes white is one of the wires and is not a Neutral.

[Boiler]

Hello criskolo,

Welcome to the forum.

The behavior you described can be caused by a number of reasons -

• The load on the adjacent X10 switch is generating noise (CFL or electronic ballast) and preventing the XPT communication from being heard by other devices.
• Your X10 transmission levels are marginal, switching the X10 load (incandescent) is sufficient to drag the level below the receive threshold.
• Your "white" wire isn't really a neutral.

I'm a little concerned by the fact that this was once a three way circuit.  If you're working on the end of the circuit where power is entering, all may be good.  If this switch was the position that supplied the load (likely since you're controlling the load with the X10 switch) it's possible that the white wire isn't a neutral or not the correct neutral.

Please describe the original circuit in detail.  It's possible that the power to the two switch positions were actually fed from the opposite phases (220V present across two different black wires).  If so, we'll need to determine which phase the "white" wire belongs to.

Boiler

Edit: Just saw Brian's post (which makes a lot of sense).  Since this was once a 3-way, there should be another wire available (red?).