Landing Light Nightmare

[Lezourez]

Hi All,
I recently bought some G9 LED bulbs for my hall and landing lights.
Downstairs light is straight on/off from downstairs only, upstairs is switchable upstairs and downstairs.
I installed the downstairs ones with no problems.
The upstairs are another, matter having installed all four bulbs I put power back on and the lights are lit when I switch them off they just dim same result from both switches. However if I put one normal G9 in with the other 3 being LED's there's no problem.
So far I've checked the switch wiring and the ceiling rose wiring both seem to be OK.
I'm stumped to why this is happening, any ideas would be welcome.

Cheers
Lez

 

[Lectrician]

This is due to capacitive coupling in the parallel two way switching cable. Very common for LEDs to glow dimmly, and CFLs to flicker gently.

Nothing you can really do, other than adding a dummy load (as you have found out by adding a lamp).

 

[bernardgreen]

Capacitive coupling between the permanent live and switched live wires in the cables to the switches is allowing some current to bypass the switch and this very small current provides enough energy to light the LEDs.

www.diynot.com/forums/viewtopic.php?p=1897855#1897855

Read more: //www.diynot.com/forums/viewtopic.php?p=1955747#1955747#ixzz2clumOvpv

 

[mattylad]

And here was I expecting a discussion about an airstrip....

 

[bernardgreen]

so that is why there is a jumbo jet on the stairs. Must remember in future to turn of the landing lights

 

[ericmark]

And here was I expecting a discussion about an airstrip....

Think they are called AGL or Aircraft Ground Lights not landing lights.

 

[ban-all-sheds]

so that is why there is a jumbo jet on the stairs. Must remember in future to turn of the landing lights

And perhaps avoid discussing landing strips with Mrs Green.

 

[Lectrician]

And here was I expecting a discussion about an airstrip....

Think they are called AGL or Aircraft Ground Lights not landing lights.

"Landing lights" are on the front of an aeroplane, a little like fog lights!

 

[Lezourez]

Thanks for the advice. Is there any way of putting a dummy load i.e. a load resistor instead of a bulb? If so what kind of value are we looking at KΩs or smaller?
By the way they're Runway Lights on the ground and landing lamps on the aircraft I'm ex RAF.

 

[bernardgreen]

If you use a resistor then it will have to cope with 230 volts when the light is on and will get warm if not hot. Using a capacitor means there is no heating affect. Hence the reccomendation in my earlier post.

 

[phatboy]

My experience is this only occurs with the cheap LED lamps, the better quality ones do not suffer the same issue - maybe they have a small capacitor built in?

 

[ban-all-sheds]

And here was I expecting a discussion about an airstrip....

Think they are called AGL or Aircraft Ground Lights not landing lights.

VASIs.

 

[ericmark]

And here was I expecting a discussion about an airstrip....

Think they are called AGL or Aircraft Ground Lights not landing lights.

VASIs.

I was not involved with runway lights when working at Heathrow but Mount Pleasant on the Falklands they were called AGL's.

 

[SimonH2]

VASIs.

That is just one of the lights you'll find on (and near) an airfield.
VASI is Visual Approach Slope Indicator. As Dave Dunson quips in his "What goes up might come down" after dinner talk, they show white if too high, red if too low, and if they show green then the light is filtering through the grass and you're far too low Much more common (at least anywhere I've been) are PAPIs - Precision approach path indicators which work much the same way but give more information on your position relative to the specified glide path (usually 3˚ but can be different - London City uses 6˚ IIRC - just looked it up, it's 5.5˚ which is very steep for a turbine aircraft*).

* Turbine aircraft have two issues. Firstly they tend to be fairly slippery (more slippery = less fuel burn for a given weight and airspeed) and so take some slowing down. Secondly, they need to keep the engines spooled up in case of a go around. While a piston engine can open the taps from idle and give full power immediately, if you let the turbine spool down in a "jet" then opening the taps will do ... not a lot for a while (I believe can be anything from "a few" seconds to 30s or more depending on the engine and initial speed) which would be a bit embarrassing when you run out of runway without having got back into the air (http://en.wikipedia.org/wiki/Air_France_Flight_296) So they almost always use shallow approaches, drag aids (spoilers and air brakes) to keep the speed down, and keep some power on the engines.

Other lights you'll see :
Approach Lighting which often extends outside fo the airfield boundary (hence the "and near" above). Runway edge lighting, runway end lighting aka "stop lights" as you don't want to be going past them , centreline lights, taxiway centre and/or edge markers, a , and of course general illumination around aprons etc.

 

[ban-all-sheds]

London City uses 6˚ IIRC

http://www.youtube.com/watch?v=4c0eaofrdTo