Hi, I've recently noticed that when i switch on one of the ceiling lights in the living room it dims & then brightens as if it's like a pulse beating. Sometimes it will do it slowly & other times it will be quickly. I have two ceiling lights, one at either end of the room running off their own separate switch. The other light is fine. Any idea what's causing this & how to fix the problem. Many thanks.
Funny light
- Thread starter Tony 1
- Start date
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Been asked and answered many times
When the switch is OFF capacitive coupling between Live and Switched Live in the wiring to the switch allows enough energy to reach the lamp and make it flash. A well known problem with energy saving lamps. They save this very small trickle of energy until it is enough to make the lamp flash.
If this has suddenly started to happen with energy saving or LED lamps that were previoulsy OK then you should check that the earth conductor in the cable to the switch is still intact and connected to the earth conductors. With the earth in place the capacitive coupling Live to Switched Live is less effective.
Putting a capacitor across the lamp will absorb this energy and prevent the lamp flashing.
Capacitor 0.047uF micro Farads 250 volts AC in series with a resistor 100 ohms
Which come pre-packaged as a contact suppressor from RS Components
RS Stock No. 206-7847
Manufacturer Evox-Rifa
Manufacturers Part No. PMR209MB5470M100
There are other sources of the contact suppressors
When the switch is OFF capacitive coupling between Live and Switched Live in the wiring to the switch allows enough energy to reach the lamp and make it flash. A well known problem with energy saving lamps. They save this very small trickle of energy until it is enough to make the lamp flash.
If this has suddenly started to happen with energy saving or LED lamps that were previoulsy OK then you should check that the earth conductor in the cable to the switch is still intact and connected to the earth conductors. With the earth in place the capacitive coupling Live to Switched Live is less effective.
Putting a capacitor across the lamp will absorb this energy and prevent the lamp flashing.
Capacitor 0.047uF micro Farads 250 volts AC in series with a resistor 100 ohms
Which come pre-packaged as a contact suppressor from RS Components
RS Stock No. 206-7847
Manufacturer Evox-Rifa
Manufacturers Part No. PMR209MB5470M100
There are other sources of the contact suppressors
Excellent answer to the wrong question. 
(My bold text)
Is this a low energy lamp? We have one that comes on bright for a second but dims almost immediately then takes a few minutes to come bright again. Yours sounds like its just repeating this cycle. Swap the lamps over and see if the fault goes with it.
(My bold text)
Is this a low energy lamp? We have one that comes on bright for a second but dims almost immediately then takes a few minutes to come bright again. Yours sounds like its just repeating this cycle. Swap the lamps over and see if the fault goes with it.
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I read it wrong as it was too early in the morning.Excellent answer to the wrong question.
In answer to the actual question. The symptoms suggest there may be a resistance in the live feed due to a loose terminal, a worn contact in the switch or a poor contact between lamp and lamp holder contacts.
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