Residual current and LED bulbs

  wiganken2 18:34 25 Mar 2019
Answered

I know that low wattage LED bulbs can glow when switched off due to an induced current getting through. I also believe that this glow is harmless due to the tiny amount of current involved which only costs a few pence/year in electricity. I have a ceiling light with 4 LED G9 bulbs each rated at 5w 220/240v and 400 Lumens output and they all glow when switched off. It is a 2-way circuit using simple switches. There are no dimmer switches and the LEDs are non-dimmable. As a test I removed one of the LEDs and inserted a 28w G9 Halogen bulb and this soaked up the residual current and the other three LED bulbs did not glow. Putting the 5w LED G9 back in and all four glowed again. Even though G9 Halogen bulbs do not glow the low residual current must still be there. It is just not high enough to cause the 28w G9 Halogen bulbs to glow. I am not knowledgeable where electrickery is concerned but I am interested so my questions are: - Am I right in thinking that this means zero power is being consumed when the Halogen bulbs are used? Are the Halogens really 100% off?.

  wiganken2 08:17 26 Mar 2019

Thank you for responding. I read the article but it did not answer my questions (at the end) which referred to Halogen bulbs, not LED bulbs.

  BT 09:15 26 Mar 2019

I think your answer may be at the beginning of the article which refers to a Phosphor layer used to modify the colour of the light. This could well account for an after glow when the lamp is switched off. If you look at a Compact flourescent lamp in a dark room after it is switched off it will glow faintly for a short while due to the residual glow from the light producing internal phosphor coatings.

LED lamps and Halogen lamps are two different beasts. Halogen lamps are no different to old type light bulbs in that the light is produced from a hot wire filament. LED light is produced electronically and doesn't rely on hot wire to produce the light.

  wiganken2 10:38 26 Mar 2019

I was not talking about an after-glow of a few minutes. My LED bulbs glow permanently when off so it is a residual current effect. This residual current must always be present when off but it is not enough to cause Halogen bulbs to glow, only LED bulbs. So, because there is no glow, does this mean zero power is being consumed when switched off with Halogen bulbs fitted?

  wee eddie 11:05 26 Mar 2019

better check your Earthing Circuit.

  bremner 11:17 26 Mar 2019

I think your issue is with your electric circuit / wiring. Have a read of this click here

  Fruit Bat /\0/\ 12:58 26 Mar 2019

Worse case scenario - poor earthing and bad bonding of neutral wire to earth.

Poor switches that allow current to trickle past.

Cheap LED lamps - Capacitance inductance across live to switch wires running in same conduit / cable (twin) this is usually overcome by the ballast in the LED lights.

  wiganken2 16:45 26 Mar 2019

Question is still not answered so I'll repeat it: - Because there is no glow with Halogen bulbs fitted, does this mean zero power is being consumed when switched off? I only mentioned LED bulbs to highlight that an induced current was present but my question does not relate to LED bulbs. As I said originally I am not into electrickery so a simple 'Yes' or 'No' would be appreciated. Thanks.

  Fruit Bat /\0/\ 17:24 26 Mar 2019
Answer

does this mean zero power is being consumed when switched off?

No

but provided your wiring is good the power is so minuscule that the meter is not going to see it.

  BT 18:05 26 Mar 2019

In theory you should have no current flowing if your switch is in the Off Position.

I agree. I'm not an electrician but if the circuit is interrupted by a switch I can't see how any current should be able to flow.

Even if there was a very small current flowing its unlikely to be be sufficient to light a filament lamp so even if enough to light an LED it could still be passing through the Halogen lamp but not lighting it up. Imagine a dimmer switch you can turn it down until the lamp stops glowing but could still have a small current passing through it.

  wiganken2 18:49 26 Mar 2019

Thanks for the replies. It was the following article that put my mind at rest regarding the LED bulbs glowing-when-off situation: - click here . It sounds harmless and will only cost me pennies/year so that's why I have not been concerned about getting my wiring checked. The article did however prompt me to ask the question re Halogen bulbs which do not glow. So I think I am sorted now. I'll mark this as 'Answered'. Thanks again.

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