When used for that application by Catalina, this switch is mounted in the 120V AC Service side of the panel above the text "PUSH TO TEST LAMP" to the left of the red reverse polarity light. To test the light you push and hold the switch. The test light should light up. Once the spring loaded switch is released, it should return to the non-test position.

In the resting position there is continuity between spades 2 and 3. The middle spade is number 2 and is wired to one side of the indicator light, while the other side of the light is wired to the white pole on the incoming side of the AC Main breaker. The number 3 spade is connected to the green buss bar. The indicator light will then turn on should there be any potential difference between the white and green wires indicating a reverse polarity situation with your shore power supply.

When the switch is depressed, there is continuity between spade 2, indicator light / white side of breaker, and spade 1, which is connected to the black pole on the incoming side of the AC Main breaker. This is where the potential difference should exist with a proper shore power connection and will allow for the testing of the indicator bulb, which should turn on if it has not burnt out.

Equipped with 3 male metal spade connectors.

Dimensions:
• Face: 13/16" x 9/16"
• Body: 5/8" x 1/2"
• Depth (body only): 7/16"
• Mounting hole:1/2" x 3/4"

Ratings:
• 12A @ 125VAC
• 6A @ 250VAC

This is not a common single pole On-Off momentary switch used, for example, where one might want a pump to run only while the momentary switch is being depressed. It is unique to the application described above.