Why Timers on Tools Don’t Tell You the Whole HAVS Story

Most workplaces track hand-arm vibration exposure the same way. A tool has a stated vibration figure from the manufacturer, tested in a lab. A timer records how long an operator used it. Multiply the two, add up the HSE points, and you have your daily dose. It is quick, it is standard practice, and it has a real problem. It estimates exposure. It does not measure it.

How the current method works

The Control of Vibration at Work Regulations 2005 set a maximum daily vibration dose of 400 HSE points, with an action level at 100 points where employers must start reducing exposure. Those figures come from EN ISO 5349, a standard built in the 1990s around lab-measured tool vibration. Each tool gets an accelerometer reading under test conditions. From that, you can calculate a dose per hour of use. A grinder rated at 66 HSE points per hour, for example, hits the action level in under two hours of continuous use.

This works as a starting point. It was designed before anyone could measure vibration at the hand directly, so it was the best available option in 2005.

Where it breaks down

The gap is what the timer cannot see. Tool wear, grip, stance, glove cushioning, and the hardness of the material being worked all change how much vibration actually reaches the operator’s hand. None of that shows up in a timer log.

We have seen this play out directly. Two operators used the same tool. One recorded a vibration dose several times higher than the manufacturer’s stated figure. The other recorded a dose in line with expectations. Same tool, same job, wildly different exposure. The cause turned out to be how the first operator gripped the handle. Once retrained, the dose came back in line. A timer-based system would never have flagged this. It only knows the tool was in use, not how it was being used.

What the regulation actually asks for

Regulation 5(2c) of the Control of Vibration at Work Regulations 2005 allows for direct measurement of the vibration an employee is actually exposed to, where necessary. The timer-and-lab-figure method is not the only compliant route. It became the common one because, in 2005, the technology to measure actual hand vibration reliably did not exist yet at a usable size or cost.

What’s changed

That is no longer true. Miniature tri-axial accelerometers, small high-capacity batteries, and modern data processing chips now fit inside a sensor small enough to sit inside a work glove. A dosimeter of this kind measures the vibration actually transmitted to the hand, applies the required frequency weighting, and logs HSE points continuously through a shift. No lab estimate. No assumption about grip or stance. Just the dose the hand actually experienced.

Why this matters for your team

If your HAVS monitoring relies entirely on tool timers, you are working from an estimate that treats every operator the same regardless of how they hold the tool, how worn it is, or how they are standing. That estimate can run high for some operators and low for others, and you have no way to tell which without checking. Direct measurement closes that gap. It tells you which operators need attention now, rather than assuming exposure based on hours logged.

HAVSco has been measuring hand-arm vibration at the hand, not the tool, since 2000. This article summarises the technical case for that approach. The full white paper, originally developed by our founder, sets out the detail in full, including the accelerometer limitations and how they are managed in practice.