There is a capacitor on the aeration compressors but I just SWAG and say 2x running amp is starting amp.
1/2 hp "120v" Vertex running amp is 3.8 amps. So, for you who are smarter in the electric world than I am, what is the starting amp draw?
(No claim at all to being smart in the electric world, just throwing in my two cents.)
esshup, do you buy enough equipment that your sales rep would forward an email to one of the manufacturer's engineers? I think that would get the best answer as to the start-up amp draw, or if the spike is so quick as to be inconsequential to designing the sizing of the electrical line.
As regards the starting draw: As voltage supplied to a motor drops, then the amps must increase to perform the same work. This is generally a linear relationship. As long as the motor is still within its nameplate rating for current, then that should not create a problem. Once a motor runs for a significant time above the amp rating, excessive heat typically becomes a problem - and that will certainly shorten the life of the motor.
For start ups where there is significant mechanical resistance (like starting a compressor piston), that typically creates a starting draw that is higher than the running draw. The electrical engineers have lots of different terms to describe this additional torque load on the motor but that is miles above my pay grade. However, those loads are usually NOT linear. They typically have a square function, therefore in the case of high start-up torque, running the voltage below the design volume pays a much larger penalty.
However, I am glad to hear that your aeration compressors have a capacitor. It sounds to me that the actual experts that designed the compressors came up with an elegant solution to the problem we are discussing. Further, even if the voltage at the motor drops by more than 3% at start up and creates a little excess heat, that should be fine as the motor quickly transitions to the "running" amperage draw. I expect cycling the system on and off multiple times per hour would be the only damaging thing to do.
esshup, have you ever put on your tester when a compressor or motor was going bad? If the compressor piston started having excess friction as it was approaching failure, then the motor would be drawing more amps for the wasted "work". If the electrical wire was designed right at the design limit, then the voltage drop across the system would further exacerbate the problem. You would experience some hot wires and hot motors exactly as you have stated. When the motors are approaching failure do they typically draw significantly more amps?
Gpugh, can you ask your seller if your fountain pump includes a capacitor in the system? If you have a very long (and expensive) electric line run, perhaps you could install a capacitor in the system near your two devices? There is a chance that would be cheaper than paying for heavier gauge wire. (That is a NON-expert opinion. Be sure to ask your electrician.)
