Electrical Hazards
10. Portable Measuring Devices
Given the high number of serious accidents that have occurred in low voltage installations due to internal faults or faulty connection to portable measuring devices that caused short-circuits inside the latter and which led to an electric arc at the point of measurement, preventive measures are to be maximized in high power circuits or circuits with a high short-circuit currents, fulfilling the following conditions:
- The portable measuring devices used under low voltage are to be industrial devices and are to be provided with the necessary electrical protection in all ranges (ohms, amps, etc.) so as to protect both the instrument and the person using it in the case of being incorrectly used when taking measurements.
- When measuring voltage, the devices are to be suitable for use at the maximum rated voltage of the installation. In low voltage installations (up to 1,000 V) and due to electrical manipulation, harmonics or electrical discharges, transient voltages of several kV may appear.
- Never connect a voltage source with the switch in the ohms (Ω) position. The input protection of this circuit is to be at least that of the maximum rated voltage of the live electrical installation.
- These devices are to be checked with the necessary regularity and are to be checked on a low power (high impedance) source before being used on high power circuits.
- Electricians are to have at their disposal a copy of the instructions manual containing the safety precautions for the use of any such device.
- The degree of insulation is to be Class II (p) and the protection classification is to be at least IP 50.
