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, in Annex D, calls for a periodic in-service test (guideline: at least every 2 years), but prescribes no test voltage or method for it. The practical re-testing method comes from the US guide IEEE 978 and falls outside the IEC.

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 test Annex D gives only an interval guideline (at least every 2 years), no voltage or method. How you re-test a finished stick section by section in practice is described by IEEE 978, a US guide outside the IEC framework.

The only standardised test voltage in IEC 60832-1 is the type test. After water conditioning, the finished stick is tested at 100 kV over an electrode gap of 300 mm for at least 1 minute; IEC 60855-1 applies the same ratio to the FRP material. That is a per-design factory test, not a re-test.

For the periodic in-service test, IEC 60832-1 prescribes no test voltage or method. Annex D calls for a visual inspection and a periodic electrical test, with a guideline of at least every 2 years, the interval set by the employer. The practical method (scanning electrodes at a certain distance along the stick, with leakage current monitoring per step) comes from IEEE 978 and falls outside the IEC. A steady or decreasing leakage current is good; a rising or unstable value points to surface degradation or an internal fault.

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. Place the electrodes at their fixed spacing at the first measuring point.

3. Scanning

Apply the test voltage per the method used and move the electrodes step by step along the stick. Record the leakage current per step. A sudden or rising increase indicates a weak section.

4. Certification

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

IEC 60832-1 recommends in Annex D that sticks in use are electrically tested at least every 2 years. That is an informative recommendation; the actual interval is set by the employer. Test new sticks before first use. That is a longer interval than for gloves.

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.

IONIO Labs tests insulating gloves and capacitive voltage detectors, with a test report for every item. Hot sticks are planned but not yet part of our range. If you want them tested, get in touch. See all inspections and lab tests at IONIO Labs.

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