Checking Power-Providing Circuits
- Measuring a power wire with the intended load disconnected using a DMM will only find open circuits (open fuse or wire).
- Recommended practice: Circuits carrying approximately 200-1000 mA may be loaded with the specified test light SGT27000. Measure circuit voltage with a DMM while the test light is connected and illuminated. A reduction in the voltage present during test-light-loading indicates excessive circuit resistance.
- Recommended practice: Circuits carrying more than one ampere should be loaded with a device requiring similar current (e.g., a headlamp bulb may be effective). A reduction in the voltage present during loading indicates excessive resistance.
- Circuit current is matched to wire gauge/size; Examples:
- Conductor sizes of 24 gauge (.5 mm) or smaller are generally used to carry approximately 1 ampere (1000 mA) or less. Use of the test light to load these circuits is appropriate.
- Conductor sizes of 20 gauge (.8 mm) or larger are generally used to carry approximately 5 amperes (5000 mA) or more. Match the substitute load (measure substitute load current first as necessary) to this current level.