On Wed, 12 Jul 2017 22:30:06 +0100, Chris Holford
wrote:

In article ,
Dave, I can't do that writes
Hi, we recently installed a window version of a swamp cooler. As such, it plugs
into a wall outlet in the lounge-room. It has a new 1/3-hp (252-Watt) two speed
motor from HomeDepot.

When it turns on either in Low or High, the voltage dips for almost a second
from 125vac to 117vac then back up to 125vac. The dimming is maybe 20% longer
for the High speed.

Is there some way we can soft-start this or what? It makes the lights dim in the
house for that short period.

Before anyone launches into "house wiring," etc rest assured it is 11-years old,
copper, in metal conduits and all up to code with 200-Amp coming into the house.

I used a 14g, 3-wire extension lead in a bunch of other outlets on different
circuits and still get the same issue. I then hard wired the extension into the
main breaker panel. Same again.

I have cleaned and oiled the fan bearings, adjusted the belt and the fan turns
quite freely by hand.

What can be done to alleviate this momentary voltage drop?

Thanks
I wonder if a suitable thermistor (ntc), wired in series with the motor
would do the job simply and cheaply? E.g. EPCOS B57127P0109M301
I think it is a pretty sure bet he has a problem with the electrical
service to the home - either in the panel. the meter box, or the wires
to the house. He needs a good professional electrician to verify it
and either repair it or get the electrical service provider to fix
it.