The LED light bulbs that do not go off NEVER! Methods to solve the "problem"

A pretty funny thing that happens to me (and not only) when I replace incandescent or neon bulbs with LED bulbs (those multiled, to be clear) is this: even if I turn off the light switch, these light bulbs continue to emit a weak (but clearly visible) beam of light.

The explanation I have given is this: the parasitic capacity between the wires that bring current to the light bulb inside the walls and the walls themselves (which can be considered connected to the ground) or between the various wires present in the "track", given the presence of the 50/60 Hz alternating voltage of the 220 or 110 V light network gives rise to a small leakage current.

This current is in no able to turn on an incandescent or neon lamp, but these LED lamps, given the great efficiency and operation even for very low currents, yes.

Probably this effect would disappear if the light switch acted on both the electric wires going to the light bulbs, but so, normally, it is not. In some cases, making sure that the switch acts on the phase and not on the neutral can solve the problem, but not always. Moreover, the modification of this type involves the intervention on the electrical system which, theoretically, would have to be done by specialized personnel.

If there are several LED lamps of different types in parallel, the one that is active at the lowest voltage of all remains on, while the others remain off.

In reality, this effect exploits it to have a faint night lighting at the house, which allows me to turn quietly without turning on any light.

From the point of view of costs, electricity consumption is negligible, and, in any case, the current leakage, invisible with traditional light bulbs, would have anyway.

If, in some rooms, this faint light annoys, the solution, if you have a minimum of familiarity with the electrical systems, is very simple: you need to connect the primary of a transformer in parallel with the LED bulbs you want to keep off . This transformer can be as small as possible, and located anywhere in the house where it is. An inductance of equivalent value to that of the transformer with the open secondary would be sufficient, but this is probably more difficult to find. The power dissipated by the transformer with the non-connected secondary is negligible (much less than 1W, typically for small transformers).

Only if the leakage currents are very limited, it should be sufficient to place at the ends of the LED bulb, instead of the transformer primary, an economic resistance of 220 kOhm, 1/2 W. This should prevent the LED bulb may form a voltage that ignites it.

The resistive element must be connected near the lamp socket, ie downstream of the switch that turns the light on and off. I repeat that the work can be done by practical people of the matter, remembering to remove the electric current before operating! With long phase connections, it is likely that 220 kOhm may not be sufficient to scale the voltage at the ends of the bulb to levels below that which causes it to turn on. The solution with the small transformer is certainly more effective. Possibly you can connect 2 resistors, always 220 kOhm, 1/2 W, in parallel.

In the diagram below you can see summarily what was said previously.

Another element that can cause the anomalous lighting of the LED bulbs, sometimes with annoying flashes, even when they should be off is the small indicator light of the switch that in some cases is inserted in the switch itself.

Its purpose is to identify the position of the switch even in the dark.

This tiny bulb, usually with a gas discharge, actually causes a current flowing in the load managed by the switch (the light bulbs in the room) when these should be turned off.

If this very small current does not cause any side effects with incandescent lamps, LED lamps may have dim lighting or flashing.

Solution: either the gas discharge indicator is removed or the first solution described above is chosen, as the resistance alone is usually not sufficient to solve the problem.

In the photos below an example of the gas-discharge warning lamp mentioned in this part of the article.