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Lights dimming

D

Den

Jan 1, 1970
0
Group:

I need to be lead gently (but not too gently through this one!).

In my home in California (110V) why is it that (for example) a light will
noticeably dim when a heavy duty appliance is turned on on the same circuit,
but not when it is turned on on another circuit?

Why didn't I see this effect when I lived in the UK (240V)?

Cheers

Den
 
Den said:
Group:

I need to be lead gently (but not too gently through this one!).

In my home in California (110V) why is it that (for example) a light will
noticeably dim when a heavy duty appliance is turned on on the same circuit,
but not when it is turned on on another circuit?

Why didn't I see this effect when I lived in the UK (240V)?

Cheers

Den
ckt1 A============Bappliance====lite

ckt2 A======================Blite
There will be a voltage drop on the conductors on ckt1 from point A
to point B when the appliance turns on. ckt2 conductors will not experience
a voltage drop when the appliance turns on, since they are not connected to
the appliance.
Therefore, when you plug the lite into ckt2 it does not dim like it does
when plugged into ckt1
 
D

Den

Jan 1, 1970
0
OK thanks for this ... but why wasn't the same effect visible on 240V ... is
it an effect that is proportional to the voltage or square of the voltage?

D
 
A

Andrew Gabriel

Jan 1, 1970
0
OK thanks for this ... but why wasn't the same effect visible on 240V ... is
it an effect that is proportional to the voltage or square of the voltage?

Sort of, square of the current actually, all other things being equal.
It's probably actually worse than this as all other things aren't equal
(in particular conductor crossectional area for equivalent voltage drop
losses would need to be 4 times those in the UK for same power circuit).
See a recent thread where exactly this point was discussed.

Filamant lamps themselves accentuate voltage fluctuations in their
light output -- you might find retrofit compact fluorescents and
regular fluorescents with electronic control gear are better at masking
the voltage fluctuations.
 
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