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HAVS calculator

Add the tools an operative will use today and how long each is on trigger. You get the HSE exposure points, the daily A(8), and where that sits against the action and limit values. The same maths SiteLynx runs inside a RAMS.

–pts
Daily exposure points
0
Daily A(8)
–m/s²
Add a tool and its trigger time.
Action value 100 points (A(8) 2.5 m/s²). Limit value 400 points (A(8) 5 m/s²). Magnitudes from the library are typical; the figure on your tool's declaration or your own measurement takes precedence. Guidance, not legal advice.

How the points work

2 × a² × t
points for one tool: magnitude squared, times hours on trigger, doubled
100 points
Exposure Action Value, A(8) 2.5 m/s². Act to reduce exposure, start health surveillance
400 points
Exposure Limit Value, A(8) 5 m/s². Must not be exceeded

A breaker at 12 m/s² reaches the action value in about 21 minutes and the limit in under an hour and a half. A cordless drill at 2.5 m/s² would take eight hours to reach the action value. That gap is why the tool choice matters more than the shift length, and why the library lists a magnitude against every common tool.

Questions people ask

What is the HSE points system?

A way of adding up vibration exposure across a day without logarithms. Every tool scores 2 × (magnitude in m/s²)² × (trigger hours). 100 points in a day equals the Exposure Action Value of 2.5 m/s² A(8); 400 points equals the Exposure Limit Value of 5 m/s² A(8). It comes from the Control of Vibration at Work Regulations 2005 and HSE guidance L140.

What is trigger time?

The time the tool is actually running in the operative's hands, not the length of the shift. A breaker used on and off through a morning might have 40 minutes of trigger time. People routinely overestimate it, so observe or time it rather than guess.

What happens above the action value?

You must take action to reduce exposure so far as is reasonably practicable: different tools, job rotation, better maintenance, less time on trigger. Health surveillance for the people exposed becomes a duty. Guidance, not legal advice.

What happens above the limit value?

The limit must not be exceeded. If the calculator says a planned day goes over 400 points, the work has to be re-planned before it starts: more people rotating, lower-vibration plant, or a different method altogether.

Where do the tool magnitudes come from?

The library values are typical in-use figures for common construction tools. Manufacturers' declared values are measured in ideal conditions and often understate real use, which is why HSE suggests adjusting them upwards. If you have measured your own tools, use your figure.

Also free: the noise exposure calculator and the risk assessment library.

Put it in the RAMS automatically

Pick the tools in the SiteLynx RAMS editor and the HAVS and noise assessments fill themselves in, with the points, the controls and the health surveillance note. Signed on site on a phone. 14 days free.

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