Electrical Code and Installation Requirements
What the exam expects
You must know how the Canadian Electrical Code is structured and how to apply it, not just quote it. Expect questions on conductor ampacity and derating, overcurrent protection and coordination, bonding and grounding, box fill, working clearances, wiring methods in different locations, and requirements for receptacles, GFCI and AFCI protection, and motors. Know the difference between the code book rules and the manufacturer's instructions: where the two conflict, the stricter requirement normally governs, and listed equipment must be installed per its listing.
Traps to watch
- Ampacity vs. protection: the allowable ampacity of a conductor and the rating of the overcurrent device protecting it are separate calculations. A common trap gives you a derated ampacity and asks which breaker is permitted; remember the "next standard size up" rule applies only in defined circumstances.
- Temperature ratings: you must use the correct column for the conductor and termination, and apply the lowest termination rating when equipment ratings differ.
- Bonding vs. grounding: bonding connects metal parts to create a fault path; grounding connects the system to earth. Questions swap these terms deliberately.
- Box fill and support: count conductors, devices, clamps, and grounds correctly, and remember support distances differ by wiring method.
- Wet and damp locations: fittings and boxes must be listed for the location, not merely installed carefully.
Rule of thumb
When a question gives you more data than you need, identify the single code rule being tested before calculating. For a derating question, the sequence is: find base ampacity from the correct table, apply correction factors for ambient temperature and conductor count, then compare with the overcurrent device. Write the steps down; most errors are skipped steps, not wrong tables.
Worked example
A conductor with a base ampacity of 90 A is derated to 72 A. The load is 65 A. A 70 A breaker is acceptable only if the calculated load does not exceed the derated ampacity and the next-standard-size rule is permitted for that installation; otherwise protection must not exceed the conductor's capacity. State the rule you relied on.