Leakage Current in Single Phase AC Motor

Thread Starter

DJZ

Joined Nov 22, 2023
3
Hi all,

I have a single phase motor (115VAC 1/4hp) that keeps failing our internal leakage current test. We are measuring about 0.1mA of leakage current when the pump is plugged in, but powered off.

The only thing the the live is wired into is an IEC connector then into a two-terminal SPST switch rated for 277VAC. The neutral is not wired through the switch and the earth is connected to the motor chassis.

With the motor plugged in and powered off, I am measuring 117.5VAC on the live terminal and 0.98VAC-1.2VAC on the neutral terminal. Any ideas on what could be causing this leakage current when the pump is power off?
 

MaxHeadRoom

Joined Jul 18, 2013
28,513
Did you try bypassing the switch and connect direct, test by using the breaker or other means to disconnect the pump power.
Probably require a method of elimination.
 

Thread Starter

DJZ

Joined Nov 22, 2023
3
Did you try bypassing the switch and connect direct, test by using the breaker or other means to disconnect the pump power.
Probably require a method of elimination.
I will give that a try and report back. Thanks for the reply.
 

Thread Starter

DJZ

Joined Nov 22, 2023
3
Did you try bypassing the switch and connect direct, test by using the breaker or other means to disconnect the pump power.
Probably require a method of elimination.
I completely disconnected the live from the motor (switch no longer in circuit) and left the earth and neutral connected. Still seeing 0.98VAC between earth and neutral despite the disconnected live. Is this normal?
 

MaxHeadRoom

Joined Jul 18, 2013
28,513
With a high impedance motor it would be normal, to test for valid earth leakage a 1k resistor is placed from N to Earth and see if voltage is sustained.
 
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