I've just tried a 9W energy-saving bulb in one of my house light fittings, and discovered that when it is switched off, it flashes briefly at about 2 second intervals. A normal bulb exhibits no malfunction (seemingly).
The light in question is a 2-way switched light on a landing. The cable from the 2-way switches connects to the mains power and to the cable to the bulb at a junction box in the loft. There is no "gizmo" (dimmer, security timer, etc) on this particular light, although I do have such on some other lights in the house.
With the power off, I have measured the (normal) resistance of the bulb circuit and the switch circuits at the junction box and at the switches. All circuits that should have been open-circuit were. There was no indication on my multimeter of any continuity across the cores of the lamp or switch cables or to earth.
However, with the power on, with the switch-live-return disconnected at the junction box, and with the switching circuit open, I can measure a voltage (of about 20V AC) between the switch-live-return and both the live-to-the-switch and earth.
Suspecting the switches, I completely disconnected the "outermost" switch and replaced the "innermost" switch (which was a bit old) with a new switch in 1-way mode. With the switch-live-return still disconnected at the junction box and the new switch open, I could still measure about 20V across the switch connections.
Suggestions? Any chance this could be due to some harmless "induced" voltage? I'm hoping so, because we were changing the light bulb (and lamp shade) only after having just finished more than a couple of months work stripping, sanding, filling, repairing, and repainting the landing and stairwell ...
The light in question is a 2-way switched light on a landing. The cable from the 2-way switches connects to the mains power and to the cable to the bulb at a junction box in the loft. There is no "gizmo" (dimmer, security timer, etc) on this particular light, although I do have such on some other lights in the house.
With the power off, I have measured the (normal) resistance of the bulb circuit and the switch circuits at the junction box and at the switches. All circuits that should have been open-circuit were. There was no indication on my multimeter of any continuity across the cores of the lamp or switch cables or to earth.
However, with the power on, with the switch-live-return disconnected at the junction box, and with the switching circuit open, I can measure a voltage (of about 20V AC) between the switch-live-return and both the live-to-the-switch and earth.
Suspecting the switches, I completely disconnected the "outermost" switch and replaced the "innermost" switch (which was a bit old) with a new switch in 1-way mode. With the switch-live-return still disconnected at the junction box and the new switch open, I could still measure about 20V across the switch connections.
Suggestions? Any chance this could be due to some harmless "induced" voltage? I'm hoping so, because we were changing the light bulb (and lamp shade) only after having just finished more than a couple of months work stripping, sanding, filling, repairing, and repainting the landing and stairwell ...