bud-- wrote:
Percival P. Cassidy wrote:

On 04/06/09 01:19 pm Jeff Wisnia wrote:


If the LED bulb stops glowing when the incandescent is put in then I
agree with the other posters who said that capacitive coupling, probably
in a "switch leg" piece of cable is letting enough current run through
the LED bulb to make it glow.


Yes, with a regular incandescent bulb in one fitting, the LED bulbs in
the other two fittings do not glow.


I agree with Jeff (and others).

A common test device is a simple neon light with 2 tests leads. If you
plug one lead into the hot side of a receptacle and hold the other lead
the neon light will light up (very dimly). This works if you are
isolated with only extremely high resistance path to anywhere. There is
a *very* small capacitance from your body to ‘the world’.

Yup, that human body capacitance is commonly accepted as being 100
picofarads for an avergage sized homo sapiens.

That's the capacitance which stores a high voltage charge when you
scuffle across a rug, and then discharges to something else (like your
cat's nose) when you get too close to it.

Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.

The capacitance between parallel wires is far higher and could drive a
small current to the LED bulbs and produce a small amount of light.