Glossary: Energy-Based Safety terms

Energy-Based Safety (EBS): An approach that ranks hazards by the amount of energy that could reach a person, because more energy means more severe injury. It focuses effort on the hazards most likely to kill or maim.
Joule (J): The SI unit of energy. This site uses it for gravitational energy (mass times gravity times height) and kinetic energy (half of mass times velocity squared). One joule is also one newton-metre, the energy of a one newton force acting over one metre, but on site newton-metres usually describe torque settings, so this site states energy in joules and foot-pounds.
Foot-pound (ft-lb): An imperial unit of energy. One foot-pound is about 1.36 joules, and 1500 joules is about 1106 foot-pounds.
High-energy hazard: A hazard with 1500 joules or more available to transfer to a person. Research links this level to serious injury or fatality as the most likely outcome.
1500 joule trigger: The planning threshold used to flag high-energy hazards. It is a prompt for direct controls, not a boundary below which a task carries no risk.
Direct control: A control specifically targeted at the energy source that effectively prevents contact or release when installed, verified and used, and that still works when someone makes a mistake. Training, signage and ordinary PPE alone are not direct controls. See direct control examples by energy source
Energy Wheel: A prompt of ten energy categories used to scan a task for hazards. Crews naturally spot gravity and motion; the wheel forces a look at the categories they miss.
Line of fire: The path energy would take if released. Position, distance and exclusion move people out of the line of fire, and are often the difference between an incident and an injury.
Stored energy: Energy held in a system that can release without warning: pressure in pipework, charge in capacitors and batteries, tension in springs and cables, a load held at height.
SIF: Serious injury or fatality. Energy-Based Safety exists to prevent SIF events specifically, not only to reduce total recordable counts.
Severity potential: The worst credible outcome if the energy present reaches a person, judged from the energy itself rather than from past luck.
Trigger question: A question asked when an energy type cannot be usefully calculated in the field. Answering it needs a competent person, not a formula.
Conservative assumption: An input chosen to overstate rather than understate energy when the true value is unknown, so the calculated result errs on the high side.
Exclusion zone: A physically marked area that keeps every person out of the line of fire while energy is present.
Competent person: Someone with the training, knowledge and experience to make the specific judgement in question, and recognised by the site to make it.
Safe Plan of Action (SPA): A pre-task conversation where the crew states the energy present, the direct controls and who verifies each control before work starts.