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Wireman · Testing how-tos troubleshooting · 2023 NEC ·

Testing how-tos

How to run the tests: meters, megger, tracing, finding faults.

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Verify a circuit is dead (live-dead-live)Prove absence of voltage the right way: rated meter, every source locked, every conductor tested, tester proved before and after.Up to 7 steps Use a multimeter: volts, ohms, ampsSet up the meter for volts, resistance and continuity, or amps, and read what it tells you.Up to 3 steps Clamp meter: amps, inrush and balanceRead running current, starting current, phase balance and leakage without opening the circuit.Up to 3 steps Megger a cable or motorIsolate it, pick the test voltage, run the insulation test, read the result and discharge.Up to 4 steps Find a short by splitting the circuitCut the circuit in half at a box, test each half, and keep halving until the short has nowhere to hide.Up to 5 steps Trace and identify a circuitFind the breaker, follow a cable through walls, or ring out one conductor in a bundle.Up to 3 steps Test a capacitorDischarge, inspect, measure microfarads, and check it under load.Up to 5 steps Test a breakerWhat you can really check in the field, and when a breaker needs proper trip testing.Up to 5 steps Check phase rotationUse a phase-sequence meter before you land motors or connect a second source, and fix it by swapping two lines.Up to 3 steps Voltage drop test under loadCompare voltage with no load and full load to find long runs, small wire and bad connections.Up to 5 steps Measure ground resistanceFall-of-potential with stakes, or a clamp-on tester, and what each can and can’t tell you.Up to 4 steps Find a hot connection with a thermal cameraScan under load, compare like with like, and judge how serious a hot spot is.Up to 4 steps