Occupational Health and Safety, and Environmental Protection
This domain tests whether you can recognize and control hazards on a customer's premises and handle refrigerants, gases, and waste lawfully. Questions often present a scenario - a suspected CO leak, a locked panel, a recovered charge - and ask for the next safe action.
Hazard control and the site
- Apply the hierarchy of control: eliminate, substitute, engineer, administer, then PPE. PPE is the last line, not the first.
- WHMIS 2015/GHS: read the SDS and label before opening any product; keep decanted chemicals labelled.
- Electrical work: treat every conductor as energized until tested. Lock out and tag the breaker or disconnect, then verify at the load with a meter rated for the category. CSA Z462 governs arc-flash and shock risk; a CAT II meter is not acceptable at a service panel.
- Gas appliances: only a licensed gas technician may connect, test, or repair gas piping. Leak-test with soap solution or a calibrated combustible-gas detector, never a flame.
- Carbon monoxide: a yellow, sooting flame or a spilling draft hood is an emergency. Ventilate, evacuate, and refer to the gas utility; do not "adjust and leave."
- Refrigerants: federal halocarbon and ozone-depleting-substance rules prohibit venting. Recover into a certified cylinder, never overfill, and follow TDG rules when transporting.
- Older appliances may contain asbestos, lead solder, mercury switches, or PCBs in capacitors; treat unknown material as hazardous and follow provincial disposal rules.
Worked example
You attend a gas range with a yellow, lifting flame and soot on the cooktop. Reasoning: incomplete combustion produces CO. You shut off the appliance, open windows, keep occupants out, and use a calibrated CO analyzer at the draft hood; you do not use a match. You check for blocked burner ports, wrong orifices, and a blocked flue. Because the cause involves gas supply and venting, you refer the gas-side correction to the licensed scope and document your readings.
Traps
- Trusting a breaker label instead of testing at the load.
- "Bleeding" a little refrigerant to clear gauges.
- Using an uncalibrated detector as proof of safety.
- Leaving a customer to use an appliance you know is unsafe.