Guide to Safe High Voltage Testing Methods

High voltage testing checks whether cables, switchgear, transformers, motors and lab equipment can safely withstand service voltages and surges. The biggest risk is electric shock. Do three things every time: plan the test, isolate and prove de-energised, and use the right method, PPE and earthing/discharge controls.

Safe HV Testing in Australia 

Applying controlled stress (AC/DC/VLF/surge) to prove dielectric with stand, detect insulation resistance (IR) issues, and find defects (e.g., partial discharge or tan delta loss). Used in utilities, manufacturing, mining, pharma, and research labs during commissioning, maintenance, and after repairs.

Top Three Controls

1. Plan: written test plan, risk assessment, drawings.

2. Isolate & Prove De-energised: lockout/tagout, test for dead, set approach distances.

Use the right method & PPE: method per standard/OEM, barricades, observers, earthing, discharge rods.

What is High Voltage Testing? 

High voltage (HV) testing uses elevated test voltages to check whether insulation systems can withstand normal and abnormal stresses (steady-state, switching surge) without breakdown. It covers cables, switchgear, motors, transformers, lab HV supplies and more. The IEC/AS-NZS 60060 family is the technical backbone for HV test techniques.

Methods at a Glance

When to use each: Commissioning (withstand plus diagnostics), maintenance (IR trend, VLF+tan δ/PD), post-repair (targeted hipot/surge).

Australian Standards & Legal Duties (Know the Rules) 

AS/NZS 60060 (IEC 60060 series): sets definitions, measuring systems and on-site test requirements for HV test techniques. Recent IEC updates (e.g., IEC 60060-1:2025) clarify scope for AC, DC and impulse testing above 1 kV. Use these standards to select test voltages, durations, and measuring systems. 

WHS duties & Codes of Practice: The Model Code of Practice, Managing electrical risks is an approved code under the WHS Act. Following an approved code will assist with compliance; an equivalent or higher method is acceptable. States publish their own approved versions (e.g., NSW 2019, QLD 2021/varied 2025). 

Victoria (Blue Book): If operating in Victoria, use The Blue Book 2022 for work on/near HV apparatus, approach distances, permits, roles, sanctioning and more. It’s referenced under Victorian regulations and sets minimum safety requirements.

3-step “Prove Competence”

1. Engage a competent person (typically a licensed/registered electrician or inspector with HV competency).

2. Use a documented procedure aligned to the Code/standard.

3. Keep records plans, permits, isolation tests, results, and calibration traceability.

Quick Reference Links

• SafeWork NSW: Managing electrical risks (Code of Practice).

• WorkSafe Victoria: Electrical safety guidance.

• WorkSafe QLD: Managing electrical risks (Code of Practice).

• Energy Safe Victoria: Blue Book 2022.

Core Methods & How to Run Them Safely 

Dielectric Withstand (Hipot)

Purpose: Prove withstand capability under elevated AC or DC voltage; go/no-go.Typical setup: kV output, defined ramp/dwell; leakage monitored. Always discharge with a rated rod and earth before removing leads.

Safe sequence 7 steps

1. Confirm isolation, LOTO, permits and approach distances (Vic sites: Blue Book).

2. Bond the test set earth first; attach the return/guard as per OEM.

3. Post barricades/signage; nominate a dedicated observer.

4. Ramp to the specified test voltage; hold for the dwell (often minutes per OEM/standard).

5. Record voltage, time, leakage current, ambient conditions. (Use the test plan template below.)

6. Lower to zero and allow the internal discharge cycle to complete.

7. Apply the discharge rod to the DUT until confirmed de-energised; earth/short the DUT.

AC vs DC: DC can over-stress aged polymeric cables; VLF AC with diagnostics is preferred for service-aged MV cables.

Insulation Resistance (IR)

What you get: A 1-minute IR value (MΩ/GΩ) and optional PI (10-min/1-min) or DAR ratios. Great for baseline and trending.

When IR beats Hipot: Routine checks where you don’t want to apply high stress; first look after maintenance; quick pre-commissioning screen before withstand tests.

VLF AC for Cables

When to use: Commissioning/maintenance of modern polymeric MV cables; safer on capacitive loads than 50/60 Hz. Post-test, discharge and earth the circuit and maintain signage until proven safe.

Tan Delta (Dielectric Loss)

What it shows: Changes in dielectric loss indicate ageing or moisture trees. Pair with VLF to plan repair/replacement windows. hvinc.com

Partial Discharge (PD)

Why run it: Finds defects (voids, sharp edges, bad joints) before failure. Combine with VLF and tan δ for a fuller picture. Calibrate the PD measuring system to IEC 60270 before testing and document PD inception/extinction voltages.

Surge/Impulse (For Motors & Windings)

Use case: Detect turn-to-turn and phase-to-phase weaknesses early, faults that IR/hipot may miss. Compare waveforms between phases; a left-shift or amplitude change flags a winding issue.

Safety Controls & Site Setup (Zero-harm Checklist) 

• Plan the test: Write a test plan with drawings, switching schedule, permits, required competencies and emergency steps.

• Isolate, LOTO, test for dead: De-energise; lockout/tagout; prove dead; define approach distances (Blue Book for Vic).

• Barricade & signage: Set exclusion zones; assign a dedicated observer with radio.

• PPE & insulated tools: Arc-rated clothing, dielectric gloves/boots, hot sticks per site risk assessment.

• Earthing/grounding: Earth the DUT and adjacent equipment; keep ground sticks and discharge rods rated for the job.

• Post-test discharge: Lower voltage to zero, wait internal discharge, then apply discharge rod; for DC tests, hold grounds for at least 4× test duration on long cables.

Incident reporting: Notifiable electric shock events must be reported promptly (e.g., SA guidance notes enforcement). SafeWork SA highlighted 331 notifiable shocks in one period and under-reporting penalties apply.

Who should perform HV testing? 

A competent person should perform and interpret electrical tests, usually a licensed/registered electrician or a licensed electrical inspector with HV competency. 

Calibration Matters: Keep HV instruments calibrated by ISO/IEC 17025 labs and maintain uncertainty statements with your results. Many enterprises set 6-monthly cycles for critical HV gear. 

Evidence & Why it Matters (Stats) 

• Electrical fatalities: 11 in AU/NZ for 2023–24 (10 in Australia), 0.34 deaths per million. Most network-related deaths involved overhead conductors.

• All-cause WHS fatalities: 188 worker deaths in 2024; 1.3 per 100,000 workers.

• Shock notifications & enforcement (SA): Hundreds of shock injuries were reported, with regulators warning on under-reporting and issuing more enforcement notices.

Choosing Test Equipment (Buyer’s Quick Tips) 

• Match method to asset: IR for trend baselines; VLF for MV cables; tan δ/PD for diagnostics; surge for motors; hipot for withstand.

• Confirm standard alignment: Check equipment and procedures align to AS/NZS 60060/IEC guidance for test voltages, dwell times and measurement.

• Safety by design: Look for integrated discharge features and proper earthing points; ensure suitability for capacitive loads (VLF).

• Insist on calibration certificates: Use ISO/IEC 17025 labs and retain uncertainty with results for audits and decisions. (Best practice reinforced by WHS Code record-keeping.)

Downloadable tools

• HV test plan template (.doc): sections for assets, standards, roles, approach distances, isolation, and acceptance criteria.

• Pre-start checklist (.pdf): PPE, barricades, earthing points, observer, comms test.

Risk matrix (.png): quick consequence/likelihood chart for on-site use.

FAQs