Re-Testing of Dielectric Electrically Insulating Boots

How are the boots supplied tested.

Every pair of Dielectric boots is electrically tested to EN 50321:2000 prior to dispatch. The test involves filling the boot with water and submerging it in a water bath, an electrode is placed inside the boot, with a second electrode connected to the metal frame of the bath. A test voltage is then applied. Boots are tested at 5kV for leakage current and are then submitted to a withstand test at 10kV for three minutes.

We regularly test samples from production at 20kV (which requires a slightly different setup for the test rig), and customers can specify boots are tested at this higher voltage if required. We also regularly perform a dry withstand test on the sole of the boot at 35kV (the boot is filled with ball bearings rather than water and stood on a metal plate) and again, customers can specify this test if required.

Re-testing

Not many people are aware that Annex B2 of the standard for dielectric footwear - EN 50321:2018 (Electrically insulating footwear for working on low voltage installations), requires that all approved dielectric footwear is re-tested every year.

We test every pair of dielectric boots to the methods in the EN 50321 standard during manufacture. Part of this test method, the 'Proof Voltage Test' should be performed annually (or at the interval defined in local national standards if this is different), once the boots are in service, along with a thorough visual inspection of the boots.

A Proof Voltage Test requires that the boot be filled with either water or ball bearings to within 4cm of the top of the boot and that it is submerged in a tank of tap water to the same level. A probe is placed inside the boot and the circuit is completed through an earthed electrode in the water tank. For a routine Class 0 test, a voltage of 5kV is applied for one minute and the current passing through the probe must be less than 5mA for a moulded boot.

This is why our boots have a space to record periodic inspection testing next to the CE markings on the boot. This requirement applies to all CE marked dielectric footwear from every manufacturer - if boots are not re-tested then they are effectively no-longer compliant to the standard.