Ensuring accurate and safe measurements when working with foil insulation is crucial for your safety and potential compensation in the unfortunate event of an accident or injury. Here's what you need to know:
Understanding Touch Voltages: What It Means for You
- You've successfully determined that an electrical installation is safe through de-energised testing. Yet, your high impedance voltmeter suggests there might be a touch voltage. What now?
- Recognize that high impedance meters can sometimes display voltages due to other factors than just the mains supply or electrical systems.
- These readings can arise from capacitive coupling with nearby non-energised wires or conductive parts.
Why It Matters
- The readings you're seeing? They might be misleading. The coupling effects can lead to:
- Difficulty in determining if the test circuit or part is energised.
- Confusion during testing.
- Potentially unnecessary practices, like disconnecting or isolating.
Testing the Right Way
- Identifying "Sustained" Voltages:
- Connect a low impedance load alongside your high impedance voltmeter.
- A suitable resistor across the voltmeter's terminals can achieve this for digital voltmeters.
- Measure the circuit. Does the reading remain steady? It's likely from a sustained source. If it drops near zero, it's an induced voltage from within the setup.
- Safety Thresholds:
- Readings adhering to clause 3.9.2 of AS/NZS 3017 Electrical Installations - Verification Guidelines typically indicate no electrical danger.
- Choosing the Right Instruments:
- Ensure the device's function, range, and accuracy class suit your work and conditions.
- For info on instrument features and measuring sustained voltages, consult the manufacturer or their rep.
Important Resources
- Your work is electrical work. Stay updated with the Electrical Safety Regulation 2013 section 9.
- Dive deeper with the Managing electrical risks in the workplace code of practice 2021 (PDF, 1.25 MB).
- For specifics on measuring touch voltage, turn to AS/NZS 3017 (see clause 3.9).
Safety is paramount. Understanding your tools and the nuances of your measurements ensures not only your safety but also safeguards your rights and compensation avenues in case of mishaps. Always be informed and stay vigilant!