How do I know how long I actually work with a power tool?

This is something that a lot of operators and employers find difficult to estimate. In fact most will drastically overestimate this time period, which of course has a devastating effect on the results of an HAV risk assessment. The time that passes while the machine is actually switched on and applied to the work is usually a very short time, perhaps seconds per application e.g. drilling a hole. This is referred to as ‘Trigger Time’. If repetitive work is involved then a simple timing exercise is all that is needed to establish an operator’s daily trigger time. 

Example: If it takes 5 seconds to drill a hole, 6 mm diameter x 40 mm deep, and the operator is likely to drill 150 holes in the working day, then 150 x 5 seconds = 12 minutes 30 seconds total daily trigger time. 

A recent survey by a European standards agency has revealed that typical daily trigger times in a lot of cases are between 10 and 30 mins maximum, with some rare applications reaching up to 3 hours. With this in mind it will in many cases be unlikely that an operator will exceed the new Exposure Limit Value (ELV) of 5 m/s² (A8). 

The following table shows a selection of power tools and an operator’s typical daily Trigger Time, as determined by a recent EU survey (CEN/TR15350).

 

Tool type	Normal application	Intensive application	Extreme application
Mini grinder	30 min	1 h 30 min	3 h
Angle grinder	30 min	1 h	2 h
Small rotary hammer	15 min	30 min
Large rotary hammer	15 min	30 min	1 h
Demolition hammer	15 min	30 min	1 h 30 min
Cordless combi	9 min
Orbital sander	30 min	1 h
Random orbit sander	30 min	1 h
Jigsaw	9 min	30 min
Circular saw	15 min	30 min
Sabre saw	15 min	30 min