Off-topic - for those who know about electronics....

[Feltwell]

I decided to fit a little LED floodlight to the end of my garage, to light up the garden if required. Only 10 watts but amazingly bright - LED technology has really come on a long way - plus it's tiny, and cheap as well.

The query is - it's wired through a single pole exterior switch, and replaced a halogen fitting. When you turn the new LED one off though it's never completely off - it always glows, not enough to worry about but enough for the neighbours to notice. Any idea why this is so? Presumably just having the neutral always connected is enough for it to do this.

Don't need to know really, just curious!

 

[a twig]

Defo shouldn't always glow, sounds like there's some leakage somewhere.

Check your wiring

 

[MikeG]

Sorry to be all bureaucratic and stuff, but this probably needs a Part P certificate from a sparky. It won't get it if you can't turn it off!! Seriously, that sounds dangerous, and I'd get someone with testing kit to have a look at it.

 

[Feltwell]

I'm not overly worried, this switch has been connected to a halogen floodlight for 10 years with no problems, and it was all tested & signed off when I built the garage. I *may* have found the answer though - the switch, which is an exterior one, has a little red LED light that is on when the switch is off, to help you find the switch in the dark. Presumably American, given reference to a "hot" wire, but Google yields this:-

Some light switches run a small amount of current through the bulbs even when off, usually to power small devices at the switch like a timer, motion sensor, or night light. Do your switches have either of those features, or something else like that?
The way those devices work is instead of having a hot/neutral pair powering the switch, they just sit inline with the hot wire and draw a very small amount of power. Old fashioned incandescent bulbs won't light up if there's only a small amount of electricity running through them, so you would never notice this current, but LEDs are much more efficient and apparently are getting enough power to run.

Think I may disconnect the little red LED and see what happens.

 

[steveb]

One of my led lights gives a very slight flicker when another adjacent circuit is energised. You can only see it if you are staring at it and the room is very dark.

The belief is that due to the the parallel cable runs , one is picking up a tiny amount of charge from the other (inducted, capacitated, incapacitated, something like that) . If I turn off the other circuit then the flickering in this one stops

Been like it 6 years so far, still not bothered.

 

[noj]

LED glow from induced current is quite common - a double pole switch would fix it.

 

[fernicarry]

The google explanation is correct, hot being the US term for live.

The switch is in series with the load as is the little light. Even with the switch off the little light is still drawing a minute current through the load and through itself. The load drops most of the voltage leaving a couple of volts for the little guy to do his thing. For decent sized loads this minute current won't bring it anywhere near to firing up but for LED fittings it can be enough to light them up a little, or even quite a lot. LED fittings incorporate a small switched mode power supply so they are capable of running off of just about anything you throw at them. Unfortunately the only way to do it when neutral isn't available, which is nearly always in the UK.

We have quite a few X10 dimmers, most are well behaved with the Phillips Master LED's I use but one isn't and it won't go all the way off. I had to replace one of the 3 LED bulbs on it with a conventional bulb to stop the other 2 from glowing slightly. Lighting shops sell a thing to stop this, which is essentially just a big resistor that brings the load back up to the minimum the dimmer expects, thereby undoing some or all of the energy saving. Ain't technology marvelous...

MK switches with illumination do take a neutral (they use small neons rated at 240V) so won't have this problem. I'd guess in your garage you'll find it relatively easy to provide a neutral if there isn't one there already. Or just chop out the little red LED...

-AL

 

[philpjuk100]

,

 

[Feltwell]

LED indicator in switch disconnected, it was indeed wired into the live, bridging the switch - and hey presto, one LED light that now switches off completely, thank you all!