The Control of Vibration at Work Regulations 2005 set the legal limits for hand-arm vibration in metres per second squared, normalised to an eight hour day: a value written as m/s² A(8). That unit is precise, and almost impossible to manage with on a busy site, because A(8) does not add up in the obvious way. Doubling the time on a tool does not double the A(8) value, and an operator who uses three different tools in a morning would need a calculator to know where they stand.
The HSE's exposure points system exists to fix exactly that. It converts the same legal limits into a daily points budget that behaves the way people expect numbers to behave: points accumulate in a straight line with time, and points from different tools simply add together. One number per operator per day, counted upwards.
The Two Numbers That Matter
The points system maps directly onto the two thresholds in the Regulations:
- 100 points is the Exposure Action Value (EAV), equivalent to 2.5 m/s² A(8). Above this level, an employer must act: introduce a programme of controls to reduce exposure to as low a level as is reasonably practicable, and provide health surveillance for employees who are regularly exposed above it
- 400 points is the Exposure Limit Value (ELV), equivalent to 5 m/s² A(8). This is the level that must not be exceeded in a working day. If it is, immediate action is required to bring exposure back below the limit
One point catches people out: the budget is per day, not per hour worked. Whether a shift runs four hours or twelve, the action value stays at 100 points and the limit stays at 400. Working longer does not buy more vibration.
How Points Are Calculated
A tool earns roughly 2 × magnitude² points per hour of use. The squaring is the crucial part. Check it against the thresholds and the system clicks into place: a tool at exactly 2.5 m/s² earns 2 × 6.25 = 12.5 points an hour, which over eight hours is precisely 100 points, the EAV. A tool at 5 m/s² earns 50 points an hour, which over eight hours is 400 points, the ELV. The points system and the m/s² limits are the same law in two languages.
The square law is also why small increases in magnitude matter so much. A tool at 7 m/s² does not sound dramatically worse than one at 5, but it earns points nearly twice as fast. Condition drives magnitude, so a worn or poorly maintained tool can quietly move an operator through their budget at a rate the brochure never suggested.
For day to day use, points are usually expressed per minute rather than per hour, and rounded up to the next whole number so that on-site arithmetic always errs on the side of safety.
From Magnitude to Time
The same rule, read as time available before each threshold:
- 2.5 m/s²: about 12.5 points an hour. EAV reached in 8 hours; the ELV would take 32 hours, beyond any working day
- 3.5 m/s²: about 24.5 points an hour. EAV in roughly 4 hours; ELV in roughly 16 hours
- 5 m/s²: 50 points an hour. EAV in 2 hours; ELV in 8 hours
- 7 m/s²: about 98 points an hour. EAV in just over an hour; ELV in about 4 hours
- 10 m/s²: 200 points an hour. EAV in 30 minutes; ELV in 2 hours
Read that last line again: a genuinely high vibration tool can consume an entire day's action value in half an hour of trigger time.
Counting Points Through the Day
Two details make the counting honest. The first is that the time that counts is trigger time: power on and hands on. Carrying a tool, refuelling it or standing next to it earns no points; only contact with a running machine does. Operators tend to overestimate this when asked afterwards, which is why measured trigger time beats recollection.
The second is knowing each tool's rate. In a manual system, each tool carries a tag showing its points per minute, and the operator keeps a running log. Use a 3 point per minute tool for ten minutes and a 4 point per minute tool for another ten, and the day so far stands at 70 points: 30 short of the action value, 330 short of the limit. Every additional tool simply adds to the same total, which is the system's whole virtue.
Weekly Averaging: The Narrow Exception
The Regulations allow occasional daily exposure above the ELV to be averaged across a week, capped at 2,000 weekly points. This is a narrow provision for exceptional and urgent circumstances, such as emergency work, and it comes with strict conditions: exposure must be below the EAV on most days, the additional risk must be reduced as far as reasonably practicable, and affected employees may need additional health surveillance. It is not a licence to run hot; exposure should always be kept as low as reasonably practicable.
Where the Magnitude Comes From
Every calculation above starts from a vibration magnitude, and the points are only as honest as that number. The HSE advise that manufacturer-quoted values are typically measured under controlled conditions and often understate real-world use, and a tool's magnitude rises as it wears. On-site vibration testing of the actual machines in use, repeated as they age, is what keeps the input, and therefore every point counted from it, truthful.
Doing This Without a Clipboard
Toolminder runs this exact system automatically. Scanning a tool's tag starts its usage timer, real trigger time is converted into points against that specific tool's magnitude, partial minutes round up so short bursts are never under-recorded, and every operator's running total is visible against the 100 and 400 point thresholds as the day happens. How HAV monitoring works covers the full loop, and the free HAV calculator shows the points arithmetic for any magnitude you type in.
HSE Resources
The HSE publishes the official tools this guide describes:
- Hand-arm vibration at work: the HSE's hub for HAV guidance
- Exposure points system and ready-reckoner: the lookup table mapping magnitude and time to points
- The hand-arm vibration exposure calculator: the HSE's downloadable calculator, which reports points per hour and time to reach the EAV and ELV
The full guidance on the Regulations is HSE publication L140, Hand-arm vibration: The Control of Vibration at Work Regulations 2005.