• • • ELECTRICAL EQUIPMENT• • •


BY DARREN BINNS, JEFFERSON TOOLS


A


sk an electrical engineer when their test instrument was last calibrated and you will get a date, or at least a sticker. Ask when the insulated screwdrivers in the same bag were last inspected and the answer is vague. Both are safety-critical, only one has a schedule. Insulated hand tools sit in an awkward gap. In certain situations they are the last barrier between a person and a live conductor, yet they are treated as consumables, bought once, carried for years, replaced when they break rather than when they stop doing what they were certified to do. Safe isolation remains the first control, and nothing here displaces it. But testing still has to be carried out on energised systems, and then a tool’s condition matters as much as the rating stamped on it.


What the 1,000 V marking actually means


The relevant standard is BS EN IEC 60900, covering hand tools for use up to 1,000 V AC and 1,500 V DC. That figure is widely misread as a test voltage. It is not: compliant tools are individually tested at 10,000 V, and 1,000 V is the working limit. The margin absorbs the tool’s real-world condition, it is not a spare capacity to spend. The standard also governs construction. A compliant tool carries two layers of insulation in contrasting colours, a primary electrical layer beneath a mechanical protection layer, so that damage announces itself. It must also carry the


double triangle symbol for live working, with the voltage marked alongside. Two points follow. A moulded plastic grip is not insulation, comfort grip handles carry no rating. And an insulated tool cannot be repaired. Once it fails, it is finished.


How insulation degrades in normal use


Insulation degrades through ordinary use. Heat is the most underestimated factor. Tools are often left against warm components, or spend summers in a van roof box, heating them up considerably. Where solvents soften some materials, the cold makes them brittle. And a screwdriver used as a lever takes the brunt of the force where the shaft meets the handle, the hardest place to see and the worst place to lose material.


The most overlooked failure mode is embedded debris. A tool carried loose alongside drill bits and swarf picks up metal fragments that embed into the outer layer. They are conductive, creating a path through insulation that still looks intact. This is why a visual check is necessary. If the contrasting inner layer shows anywhere, the tool is out of service, immediately, not at the end of the job. The same goes for cracks, cuts, soft patches and embedded particles.


INSULATED TOOLS HAVE NO CALIBRATION DATE Storage and complete sets


make the difference Part of the reason these checks slip is a quirk of classification: insulated hand tools are not categorised as personal protective equipment, so they fall outside the record-keeping habits built around gloves, mats and harnesses. The risk is no smaller.


Three things make the difference. Storage is the first: a dedicated roll or case keeps insulation away from heat, solvents and loose metalwork, and turns the pre-use check into a glance rather than a rummage. The second is complete sets, where a team has only one or two insulated items in a general kit, the uninsulated equivalent gets picked up under pressure.


The third is disposal with intent. A failed tool that goes back in the van will be used again by someone; it needs to be rendered unusable on the spot. That is easier when a single screwdriver can be replaced rather than the whole set, which is why the range is listed piece by piece as well.


Equipment is the last line of defence


None of this replaces isolation, proving dead, or a properly planned safe system of work. Equipment is the last line of defence.


But it is the line that slips most easily, because the deterioration is gradual and nothing announces it. Calibration has a date on it, insulation does not. A ten second look at the start of a task, and a documented inspection on the same cycle as everything else, closes a gap few teams have chosen to leave open.


www.jeffersontools.com 20 ELECTRICAL ENGINEERING • OCTOBER 2026 electricalengineeringmagazine.co.uk


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