Testing hot sticks per IEC 60832

A hot stick with internal degradation looks healthy from the outside. Clean surface, fittings tight, but a weakened FRP section no longer holds up under high voltage. You can’t see the risk — you measure it.

The periodic test is the only way to check the dielectric strength per section. IEC 60832-1 sets the type test and gives an interval guideline in Annex D; IEEE 978 provides the sectional test protocol used worldwide in practice.

Three standards, one tool

Hot sticks fall under three standards, each covering a different layer. IEC 60855-1 deals with the FRP tube material itself: material properties and dielectric strength per unit length. IEC 60832-1 covers the finished stick as a tool, including end fittings, marking and the type test; for the in-service interval Annex D gives a guideline. IEEE 978 is the most widely used practical protocol for the sectional in-service test. IEC sets the type test and material requirements; IEEE 978 describes how you re-test a finished stick section by section.

Test voltage: 100 kV per 300 mm section

The value of 100 kV over 300 mm comes straight from the IEC type test: IEC 60832-1 tests the finished stick at 100 kV over an electrode gap of 300 mm for at least 1 minute, and IEC 60855-1 applies the same ratio to the material. Applying that gradient section by section — sliding the electrodes step by step along a long stick — is the in-service method from IEEE 978.

The test uses scanning electrodes that move along the stick while the leakage current is monitored per section. A spike points to surface degradation or an internal fault.

Test procedure

1. Visual inspection and cleaning

Check for surface damage, deep scratches or stains. Wipe the stick clean with a dry cloth. Moisture or dirt raises the leakage current and causes false spikes.

2. Setup in the test stand

Mount the stick horizontally. Move the primary electrode to the first measuring point, earth at the other end.

3. Scanning

Apply 100 kV and move the electrode along the stick in steps of 300 mm. Record the leakage current per step. A sudden increase indicates a weak section.

4. Certification

Test report with stick length, standard, date, test voltage and measured leakage current per section.

Test interval

IEC 60832-1 gives an interval guideline of at least 2 years for sticks in use in Annex D. That is an informative recommendation; the actual interval is set by the employer. Test new sticks before first use. That is more generous than gloves, reflecting the higher mechanical robustness of FRP.

More about testing high-voltage PPE

This article is part of a series on the periodic testing of high-voltage PPE:

• Testing insulating gloves — IEC 60903
• Testing voltage detectors — IEC 61243
• Testing phase comparators — IEC 61481-1
• Testing earthing equipment — IEC 61230
• Testing insulating mats — IEC 61111

Or read the complete overview with all standards and intervals.

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