NETA Level III
Ground fault testing circuit breakers equipped with G-Series 310 and 310+ can be a real pain if you are unfamiliar with the power requirements of these trip units. The factory procedure from EATON requires you to use two primary-injection test sets and convoluted test connections for a simple ground fault test, fortunately there is a better way.
You can use the EATON Functional Test Kit to provide the 310 and 310+ trip unit with adequate sensing power for a single pole ground fault test. Simply turn the dial on the test kit to "Power Up" and hold down the "Push to test" button during your primary injection test.
I discovered this trick today while acceptance testing a 2500A switchboard main breaker (EATON RG Frame) with ground fault. I was unaware of the power requirements and tried to test the switchboard ground fault system as normal, with a single current box and a jumper.
At first I was getting no trip and a solid green LED on the trip unit which should normally be a flashing green, indicating that the trip unit is working properly. I made a phone call to another tech who is familiar with these trip units and he forwarded me this crazy procedure from EATON.
According to their procedure I needed two test sets. One to push enough current to power the trip unit through two poles in series, and a second test set to simulate the ground fault current through the free pole.
This is just a ludicrous design in my opinion and I had no additional current sources, so I had to improvise. Luckily I had the functional test kit with me and remembered it has a power up function that gave me the flashing LED.
Sure enough using one hand to hold the button and another to push current with my test set did the trick, I got the trip and no trip results I expected. No crazy procedure needed, hopefully these findings help someone out in the future.
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