JouleCheck examples
Worked examples
Six common scenarios, calculated in full. Every number here can be reproduced in the calculators: each example opens prefilled so you can change the values to match your own task. A result below the 1500 J trigger never means a task is without risk, and most tasks carry more than one energy source.
Dropped podger spanner
A 0.8 kg podger spanner dropped from steel erection at 8 metres.
E = m x g x h = 0.8 x 9.81 x 8 = 62.8 J
62.8 J (about 46 ft-lb)
Below the 1500 J trigger. Still enough to cut and concuss: a dropped-object exclusion is not optional.
Scaffold tube from the third lift
A 4.5 kg scaffold tube offcut dropped from 6 metres.
E = m x g x h = 4.5 x 9.81 x 6 = 264.9 J
264.9 J (about 195 ft-lb)
Below the 1500 J trigger, in the first-aid band of the severity research. A full 6.4 m tube of about 28 kg from the same height is above the trigger at roughly 1650 J. Exclusion and toe boards are the controls that matter either way.
Pipe spool lifted overhead
A 90 kg pipe spool lifted 2 metres for fixing.
E = m x g x h = 90 x 9.81 x 2 = 1765.8 J
1765.8 J (about 1302 ft-lb)
Above the 1500 J trigger: expect serious injury or fatality as the most likely outcome if it falls on someone. A direct control is required, with no person under the load.
Telehandler across the yard
A 7000 kg telehandler travelling at 10 km/h near people on foot.
E = 0.5 x m x v^2 = 0.5 x 7000 x 2.78^2 = 27006 J
About 27,000 J (about 19,900 ft-lb)
Eighteen times the 1500 J trigger. Plant and pedestrian segregation is the direct control, not driver vigilance.
Switchgear cabinet on skates
An 1800 kg cabinet skated at walking pace, 0.5 m/s.
E = 0.5 x m x v^2 = 0.5 x 1800 x 0.5^2 = 225 J
225 J (about 166 ft-lb)
Below the 1500 J trigger, but the number only describes the kinetic energy. Crush and tip-over exposure at hands and feet is what hurts people on skated moves. Verify the controls regardless of the number.
Pneumatic test on a chilled water main
A 100 mm bore main, 100 metres long, tested with air at 10 bar.
E = isentropic stored energy at 10 bar gauge, 0.785 m3 = about 1,070,000 J
About 1,070,000 J, roughly 710 times the 1500 J trigger
The decision was already made by presence: every pneumatic test is high energy. The number shows why the exclusion zone in the test procedure is not negotiable.
Every example assumes the mass, height, speed or pressure shown. On site, use values from a delivery note, a drawing or a measurement, and treat estimated inputs as estimates. The calculators mark them as such.