House wiring? (slightly off-topic)

[Glen]

At 02:13 PM 12/27/00 , Robert Donker wrote:
>If you test a 100 watt bulb you'll find it always draws a 100 watts, to keep
>it's side of ohm's law balanced, it must draw more current (generate more
>heat) at a lower voltage. 

The phrase "a 100 watt bulb" means a bulb rated to consume 100 watts of
power when operated at its intended voltage. If the voltage is either
increased or decreased, the wattage consumed by that bulb will deviate
accordingly. If the voltage across the bulb decreases, the wattage consumed
by the bulb will also decrease. If the voltage across the bulb is
increased, the wattage consumed by the bulb will increase, unless the
voltage is increased so much that the filament in the bulb burns out. In
that case, the wattage consumed will drop to zero.


>This proves true in the lab, you can quickly burn
>out a bulb buy lowering the AC voltage. 

I'd love to see how your lab is wired. This is the exact opposite of the
behavior that I have observed with electrical lamps.


>Sort of. The reality is its in a AC
>environment. This means it will behave like an frequency dependant impedance
>(like a speaker for example) and the actual current draw is a more
>complicated to calculate. However the ohm's law still rules. 

Ok, which is it? Either this is complicated to calculate, or it is covered
by simple Ohm's law.


>If the watt's
>remain the same and you lower the voltage the current draw will increase.

Ok, you're beginning to get it correct. *IF* the actual wattage consumed
stays the same, (not to be confused with the wattage *rating* of a
particular lamp) after you have lowered the voltage, the current *will*
increase.  HOWEVER, in order for the wattage to remain the same, we need to
switch light bulbs to another one that is rated for the same wattage as the
old bulb, but also one that is rated at the new lower voltage.   :)


If someone else wants to comment on this discussion that's fine with me,
but I see no point going any farther with this, at this time. I'll just
leave it to the good people of this list to decide which argument seems
more correct.


Later,
Glen