Posted by I can't do that Dave on March 21, 2018, 3:08 pm
We have a swamp cooler and it is getting close to the time to put it into d
aily service. When the 1/2hp fan motor switches from Low to High, or High t
o Low, there s a short delay and then it starts up again. All good since it
is a two-speed motor.
But when it starts each time the lights in the house momentarily dim, so I
am wondering if it is possible to buy a soft-start whatever and wire it in
between the motor and controller.
Last year I asked on groups about the swamp and dimming lights, but no one
mentioned a soft start, but instead suggested I get the wiring checked. Got
an Electrician in and he gave the entire house a clean bill of health. No
surprise really, the guy who built the house was an Electrician in the Navy
for thirty years.
I checked Amazon and can find nothing, but Wiki mentions them for three-pha
Posted by David Lesher on March 23, 2018, 8:03 pm
Friend bought a house from a retired Navy Chief electrician;
he'd rewired it & thought that black was neutral, just like in
Yep, 3-phase motors are another story entirely. You could
replace the motor with a 3-phase unit and a VFD; that would
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Posted by amdx on April 8, 2018, 1:43 pm
On 3/21/2018 10:08 AM, I can't do that Dave wrote:
Does the wiring to the 1/2hp motor go directly back to the breaker box.
Just doesn't seem like it should cause the lights to dim.
You have 220V coming in, which phase is it on? (I'm assuming it's a 120V
Does it help to switch that motor to the other phase?
Could there be a poor connection on your incoming lines.
Do you have an electric dryer?
An interesting test would be to monitor the voltage of one phase
while you start the dryer, then repeat for the other phase.
See if there is a difference in the voltage drop.
You might need to remove any loads that might be drawing current,
fridges, freezers, sump pump, furnace, air conditioner, to get a more
Posted by Mark F on April 9, 2018, 5:45 pm
1. What voltage does the motor run on? What are the ratings for
the motor (voltage, running current,
startup current [or at least the type of fusing specified] ?
2. What is the total service to the house
(number of phases, voltage, current)?
3. What size wire and approximate run length for the circuit the motor
4. You say lights dim. Assuming you have 2 phases in the house
and the motor runs on one phase that is 180 degrees out of phase
with the other (which is normal in the USA outside or parts of
Queens, NY, which gets 2 of 3 phases, for 208 instead of 240 volts
nominal), have you looked at lights on the other phase to see if
they get BRIGHTER when the motor starts.
If the lights that get brighter share the neutral on the circuit,
then the dimming might be normal with the usual required wiring
for a 15 Amp circuit (#14).
5. Borrow a modern motor setup of the same horsepower. See how things
act with it then evaluate replacing the "swamp cooler"
Also, to be sure we are on the same page:
Looking at Google for current swamp coolers of what seem to
be similar size, I see:
0.5 horsepower, Maximum Amperage 11.5 Amps
Can you measure the startup up current and compare it to 11.5 Amps?
(Note, the 11.5 Amps in the spec might not be the actual maximum,
so you'd need a fast meter or electronics)
Try looking at:
for circuit information there to see if you would need a 20 Ampere
Also, if the circuit is long you need to go one or more wire gauges.
So 15 Amp would need #12 of #10 instead of #14.
For 20 Amp #10 or #8 instead of #12.
(If the thing plugs into a receptacle probably should use
pigtails since the connection on the receptacle are likely
not be rated for #8 and would make things easier with #10)
I couldn't find a wiring diagram, but the web site points to:
You could look in there to see the Portacool thing has any special
This has a picture of the $00 replacement motor for the Portacool:
You might be able to read the rating/wiring label on the motor and get
some information from it.