IEC 61868-1998 — Live Working — Care, Maintenance and Testing of Tools

Key Insight: IEC 61868-1998 specifies maintenance requirements and periodic test procedures for live working insulating tools, serving as the essential safety management standard for protecting workers and extending tool service life.

1. Scope and General Principles

IEC 61868-1998 “Live working — Care, maintenance and testing of tools” applies to all insulating tools used for AC or DC live working, including insulating sticks, operating rods, insulating tongs, voltage detectors, and general-purpose live working tools. The standard does not cover specialized equipment such as live working robots.

The core philosophy of the standard is “preventive maintenance over passive replacement.” Through daily inspection, periodic cleaning, proper storage, and scheduled electrical testing, insulation defects can be identified and rectified before they develop into hazardous failures. For live working tools, even minor surface damage (scratches, moisture absorption, carbon tracking) can lead to flashover under high voltage, posing serious risk to operator safety.

Safety Warning: Insulating tools must undergo visual inspection before and after each use. If any cracks, deformation, burn marks, or signs of moisture are detected, immediately withdraw the tool from service and send it for testing. Even visually intact tools must undergo scheduled electrical withstand testing.

2. Periodic Testing Methods and Acceptance Criteria

IEC 61868 specifies two main test categories: Type Tests and Routine Tests. For in-service tools, the focus is on routine tests, including electrical insulation tests and mechanical strength tests.

2.1 Electrical Insulation Testing

Insulation testing is the key method for verifying that tools meet insulation performance requirements. The test voltage depends on the tool’s maximum operating voltage class. The standard requires power-frequency AC voltage withstand tests with a duration of 1 minute, with no flashover or breakdown as the acceptance criterion.

2.2 Test Interval and Record Management

The standard recommends routine test intervals not exceeding 6 months. Under severe environmental conditions (high humidity, chemical contamination, extreme temperatures), intervals should be shortened to 3 months. Each tool must have an independent maintenance record documenting manufacture date, commissioning date, test results, and maintenance history.

Tool Type	Max Operating Voltage (kV)	Test Voltage (kV)	Test Interval	Acceptance Criterion
Insulating Stick	12	44	6 months	No flashover/breakdown
Insulating Stick	36	70	6 months	No flashover/breakdown
Insulating Stick	72.5	105	6 months	No flashover/breakdown
Insulating Stick	170	195	6 months	No flashover/breakdown
Voltage Detector	—	Rated voltage ×1.5	6 months	Audio/visual indication OK
Insulating Tongs	—	Rated voltage ×3	3 months	No flashover/breakdown

3. Engineering Practice and Maintenance Management

Best Practice: Implement a Tool Lifecycle Management (TLM) system with RFID tagging for each tool. Test and maintenance results are recorded in real-time via handheld terminals. The system automatically issues 30-day advance expiration reminders based on test dates and required intervals.

Storage Environment Control: Storage conditions directly impact insulating tool service life. The standard recommends a storage temperature range of 10°C to 25°C with relative humidity not exceeding 60%. Tools should be stored vertically by hanging to avoid deformation. Insulating tools must not be mixed with ordinary tools to prevent oil and metal particle contamination of insulating surfaces.

Cleaning and Decontamination: Dirt and grease should be removed immediately after use. Use neutral detergents or isopropyl alcohol (concentration not exceeding 70%). Acetone, gasoline, or other solvents that attack insulating materials are strictly prohibited. After cleaning, tools should be air-dried at room temperature for at least 24 hours before insulation testing or storage.

Critical Warning: Never use abrasive cleaning materials (wire brushes, sandpaper) to remove stubborn stains from insulating tool surfaces. Any mechanical wear exceeding 0.1 mm depth damages the surface charge distribution of the insulating material, significantly reducing flashover voltage. Furthermore, no modification (drilling, cutting, painting) of insulating tools is permitted.

4. Frequently Asked Questions

Q1: Can insulating tools be used past their test expiry date?

A: Absolutely not. Tools beyond the test expiry date are considered “untested” — their insulation performance is unverified, and using them carries unacceptable safety risk. Even if tools appear intact, they must pass testing before being returned to service. It is recommended to label the next test due date directly on each tool.

Q2: Can DC voltage be substituted for AC in insulation testing?

A: In some cases, yes, but the DC test voltage should equal the peak AC test voltage (i.e., multiplied by √2). However, DC testing cannot fully reveal internal air gap discharge issues within insulating materials. The standard recommends AC withstand testing as the primary method; DC is considered only when AC test equipment is unavailable on site.

Q3: How can moisture absorption in insulating tools be detected?

A: Insulation resistance testing provides a reliable indicator: under 500 V megger testing, the insulation resistance should be no less than 1000 MΩ. Values below this threshold indicate moisture absorption or surface contamination. Moisture-affected tools can be dried in a 40°C~50°C oven for 16~24 hours and then retested.

Q4: Must used tools undergo full type testing to original standards?

A: Generally not. In-service tools require only routine testing, with test voltages moderately below type test standards (approximately 75%~80% of rated test voltage). However, if a tool has undergone major repair or replacement of critical components, full type testing should be performed.