These three tests should be in your preventive maintenance program for medium-voltage circuit breakers: 1. Contact resistance test. Use a digital low-resistance ohmmeter (DLRO), not a digital ...

Snap-on ’s new EECT900 Multi-Probe Ultra features a circuit tester and digital multimeter in one handheld device for testing AC and DC voltage, resistance, and amperage.

First, turn off the circuit breaker that powers this circuit. Inside each box you should discover four wires that connect to each three-way switch.