When and how do you test high-voltage PPE?

Anyone working above 1 kV depends on their gloves. And on their hot stick, voltage detector and phase comparator. A crack or degradation in that insulation anywhere is asking for trouble.

Yet contacts regularly come to us with the same question. Which standard applies, and at what test voltage do I test my class 4 gloves or my 3 m hot stick? In practice, people trip up over small but important differences. AC versus DC. Class 00 versus 1. IEC 60855 versus IEC 60832.

The IEC has written it all down. This page walks through the relevant standard, exact test voltage and interval for each PPE type.

One legal note. The Dutch Working Conditions Act and Decree require employers to test work equipment periodically. NEN 3140 (low voltage) and NEN 3840 (high voltage) are not law, but they are the accepted method for demonstrating compliance. For PPE above 1 kV, NEN 3840 is the relevant standard.

Each PPE category has its own IEC standard, with a corresponding interval.

Please note: the intervals in this table follow the IEC standards: for most PPE a maximum term, for hot sticks a recommended frequency (Annex D, informative). In practice, shorter intervals may apply due to manufacturer specifications, internal company guidelines or national standards. If you opt for the standard’s term, you must be able to substantiate it: storage conditions, frequency of use, risk assessment and manufacturer advice. Unsure which interval applies in your situation? Get in touch for advice.

The standards distinguish type, sample and routine tests. Periodic re-testing is set out separately in an annex. Keep these levels apart, because the level determines which test voltage is used.

The rest of this page covers the periodic in-service level, the work of laboratories and in-house setups.

Gloves are classified by working voltage. Class 00 is for low-voltage, automotive work. Class 4 is for MV network operation up to 36 kV. IEC 60903 allows both an AC and a DC test.

The DC test voltages come from IEC 60903. That is what we use for periodic testing.

Class 00 and 0 can be checked periodically by air inflation plus visual inspection. A dielectric test only at the owner’s request. For class 1 to 4 the test consists of three parts: an air test, a visual inspection under inflation and the dielectric test in a water bath (1 minute, class-dependent acceptance).

The 70 kV DC insulating glove tester we supply is adjustable between 10 and 70 kV. That covers IEC 60903 class 4 (60 kV) with ample margin, and also provides enough headroom for clients following the ASTM D120 DC proof test for class 4 (70 kV).

AC versus DC remains a question of who is looking over your shoulder. Audits often require the AC procedure. IEC 60903 allows a DC test, but nowhere calls it equivalent to AC. With DC, leakage current is not assessed either. So verify with your client which procedure they want to see on the certificate.

The full test procedure (class ratings, the water-bath setup and the AC-versus-DC choice) is covered in the article on testing insulating gloves.

A hot stick (also insulating stick, live-line tool or switch stick) is a fibreglass-reinforced rod with end fittings. Linesmen use it for live work on MV and HV installations. Lengths run from 1.5 to 12 metres, sometimes longer.

Three standards apply to hot sticks, each at a different layer. IEC 60855-1 covers the FRP material the stick is made of. IEC 60832-1 covers the finished stick as a complete tool. For the periodic in-service test the US guide IEEE 978 is often used. It is a guide, not a standard, and falls outside the IEC framework.

The type test per IEC 60832-1: after 24 hours of water conditioning, at least 100 kV r.m.s. is applied between electrodes 300 mm apart, for not less than 1 minute. For foam-filled-tube sticks an internal insulation type test is added. That is done on a 4.20 m (Cat A, Ur ≤ 550 kV) or 8.30 m (Cat B, Ur up to 800 kV) test piece, in three steps of which the heaviest lasts 1 hour at 1.5/√3 × Ur.

For the periodic in-service test, IEC 60832-1 Annex D recommends testing at least every 2 years, so with at most 24 months in between; that is an informative recommendation, the actual interval is set by the employer. Applying that 100 kV / 300 mm gradient section by section along a long finished stick (with scanning electrodes and leakage current monitoring) is the in-service method from IEEE 978.

The IEC type test applies 100 kV over a 300 mm electrode gap to the finished stick (after water conditioning); for the in-service test the IEC sets no fixed voltage. Test benches for insulating sticks (often four at once) are available on the European market. For a setup that fits your stick lengths and volume, please contact us.

The full test procedure, including the sectional IEEE 978 protocol, is covered in the article on testing hot sticks.

A voltage detector above 1 kV is not the same as an LV proving unit. The proving unit falls under IEC 61243-3 (low voltage) and has a simple calibration check. For MV and HV (1 kV and higher), IEC 61243-1 applies to the capacitive type. There is a more complex test procedure behind it. Resistive voltage detectors fall under IEC 61243-2 (1-36 kV).

The threshold voltage Ut is the voltage at which the detector reacts visibly or audibly. IEC 61243-1 requires Ut to lie between 10% and 45% of the nominal voltage Un. Formally: 0.10 × Un_max ≤ Ut ≤ 0.45 × Un_min.

That dual criterion has a good reason. A detector that only triggers above 45% of Un reacts too late: a part that is actually live gets declared dead. A detector that already triggers below 10% of Un reacts too early: interference or induced voltage triggers it, personnel get used to false alarms, and they ignore the warning.

The periodic test follows IEC 61243-1 Annex G and includes, among other steps, a threshold voltage test on a calibration stand, a function test with audible or visual signalling, a leakage current check on the insulating part under dry conditions and a visual check for cracks or internal moisture ingress. The full eight-step procedure is in the article on testing voltage detectors.

Test benches for voltage detectors are available for the MV range (up to 52 kV) and for transmission grid use (up to 245 kV). For a fitting choice, please contact us.

A phase comparator checks whether two MV or HV lines carry the same phase. Critical before switching two networks in parallel. IEC 61481-1 distinguishes two types: single-pole with memory system (up to 36 kV nominal) and two-pole wireless (up to 245 kV nominal). Resistive phase comparators fall under IEC 61481-2, limited to 1-36 kV due to ergonomic one-person operation.

The scope is wider than often assumed. IEC 61481-1 covers 1 kV up to 245 kV a.c. The idea that it “stops at 36 kV” applies only to single-pole memory units. Two-pole wireless reaches well into transmission-grid territory within the same standard.

The periodic test (IEC 61481-1) has seven steps: visual and dimensional inspection, check of the testing element, leakage current under dry conditions, bridging-protection test, spark resistance, clear indication, and clear perceptibility of the visual and audible signals.

The dielectric test voltages scale with the nominal voltage.

The in-service interval per Annex G is a maximum of 6 years. Dutch practice often shortens that to annual or biennial inspection.

Whether MV units up to 52 kV can be tested on the same test bench as voltage detectors (IEC 61243) depends on the bench. Phase comparators may need a source with adjustable phase angle. Two-pole wireless units up to 245 kV require a separate HV test bench.

The seven test steps and the two operating principles are detailed in the article on testing phase comparators.

Strictly speaking, portable earthing sets aren’t PPE. They’re work equipment. But they belong in this story. In the five golden rules for work on a de-energized installation, the earthing set comes right after the voltage detector: once you have confirmed the line is dead, you connect a set between the phases and earth to keep it that way. That catches both accidental re-energization and induced voltage from parallel circuits.

IEC 61230 covers the short-circuit rating (kA × √t), cable cross-section per rating, clamp design and in-service inspection. The type test uses a test current It = 1.15 × Ir at a peak factor of 2.5 for 50 Hz. That is a high-current test: the destructive factory test, performed once per design.

For periodic in-service testing, the standard hands the interval to the user. The test current is not entirely free: it recommends measuring continuity at no less than 10 A, with instrument resolution of at least 1 μΩ. The pass/fail values are given in ASTM F2249; each measurement is compared against the initial reading. A rising resistance means corrosion, or a crimp that is letting go.

That measurement needs a micro-ohmmeter. For cable cross-sections of 35 to 240 mm² and set lengths of a few metres, total resistance lands at about 0.1 to a few mΩ. A test current of 100 A is industry practice at manufacturers and labs, not an IEC requirement, but it generates enough heat to expose loose contacts. More in our complete guide to micro-ohm measurement.

Visual inspection remains the most important check. Cable jacket intact, clamp teeth not deformed, insulation undamaged. Before every use. After any fault event where the set has actually carried short-circuit current: replace or destructively inspect.

The full inspection and test procedure for earthing equipment is covered in the article on testing earthing equipment.

Mats go under the feet during work on switchgear and MV/HV installations. They break the path to earth through the floor. Five classes under IEC 61111, set up like gloves but without class 00.

For periodic re-testing, IEC 61111 Annex B.7 sets a maximum interval of 12 months, also for mats in storage. Class 0 needs only a visual inspection. From class 1 upwards, the dielectric proof test is mandatory (main proof test 3 minutes; the shortened conformity variant runs 1 minute without moisture conditioning), with a visual check before and after. After an incident or any real doubt, a dielectric test makes sense for class 0 too.

More on classes, re-test intervals and the dielectric test is in the article on testing insulating mats.

For periodic testing of insulating gloves, IONIO supplies a DC tester adjustable between 10 and 70 kV. It covers class 0 to 4 per IEC 60903 (DC proof test) and has enough headroom for clients who follow the ASTM D120 DC proof test for class 4 (70 kV). Product page: 70 kV DC insulating glove tester.

For hot sticks (IEC 60855-1 and IEC 60832-1), voltage detectors (IEC 61243) and phase comparators (IEC 61481) we supply on request. We know the European suppliers and help with selection, configuration and, where relevant, calibration and training.

Clients who do not want to test in-house, we refer to specialised testing laboratories in the Netherlands and Belgium.

You can test high-voltage PPE yourself or outsource the testing. Testing in-house requires your own test setup, trained staff and a fixed procedure in line with the standard. A glove tester and a test stand for hot sticks together form a complete in-house setup.

You can outsource testing to IONIO Labs. We test electrical insulating gloves to IEC 60903 and capacitive voltage detectors to IEC 61243-1, with a test report for every item.

What suits you best depends on the number of items, the test interval and your own planning. In a consultation we compare the options with you.

Looking for a glove tester, or advice on the right setup for your PPE testing process? Get in touch via the contact page.

We answer technical questions and put together a quotation that fits your situation.

IONIO tests and inspects electrical insulating gloves following the test methods of NEN-EN-IEC 60903 (air test, visual inspection under inflation and dielectric DC test, class 1–4) and capacitive voltage detectors to IEC 61243-1, with a test report for every item. See the services insulating glove testing and voltage detector testing, or all inspections and lab tests at IONIO Labs.