The Energy Wheel
The Energy Wheel is a prompt for scanning a task against ten energy sources. Field research by the Construction Safety Research Alliance found that crews recognise gravity and motion hazards naturally, but routinely miss pressure, chemical, electrical and radiation hazards. Scanning all ten categories before work starts substantially improves hazard recognition.
The ten categories, with data centre construction examples:
- Gravity: something can fall, or someone can fall. Suspended loads, work at height, dropped tools, stored materials at edges.Calculated
- Motion: something can move, strike, roll or swing. Mobile plant, deliveries, cable drums, equipment on skates.Calculated
- Mechanical: moving parts, tension, rotation, stored mechanical force. Fans, pumps, cable pulling, springs and tensioned assemblies.Presence = high energy
- Electrical: current, energisation, arc flash, stored charge. Switchgear, temporary power, UPS systems, live testing.Presence = high energy
- Pressure: compressed gas or liquid, hydraulic, pneumatic, vacuum. Pressure testing, suppression cylinders, chilled water systems.Presence = high energy
- Chemical: substances that burn, react, poison or corrode. Water treatment dosing, refrigerants, fuels, concrete.Presence = high energy
- Thermal: heat, cold, flame, steam, sparks. Hot works, load banks, exhaust systems, cryogenics.Presence = high energy
- Sound: harmful noise or impulse sound. Generators under test, drilling, grinding in enclosed plant rooms.Presence = high energy
- Radiation: ionising and non-ionising. NDT radiography, welding arc, lasers.Presence = high energy
- Biological: organisms and contaminated material. Stagnant water, drainage, pest contamination, mould.Presence = high energy
Presence or size: two different questions
The wheel asks one question for every category: is this energy present in the task? What happens next differs by category.
For gravity and motion, the size of the energy can be worked out from things a crew actually knows: mass, height, speed. Those two get calculators, and the result is compared with the 1500 joule trigger.
For the other eight, no useful field calculation exists. The energy in a live conductor, a charged main or a suppression cylinder is real and usually far above 1500 joules, but working it out needs data that only exists in engineering studies. Industry practice answers with presence criteria instead: exposure to 50 volts or more is high energy, a charged pressure system is high energy, a suspended load is high energy. Presence decides, not arithmetic.
That is why every energy source on this site is either calculated, or treated as high energy when present and verified with trigger questions.
How to use it: before the task starts, go around the wheel and ask for each category, "Is this energy present in this task, and could it seriously hurt someone?" For anything that could, identify the direct control and verify it is in place. The task pages on this site do this scan for common data centre construction activities.