309A Cheat Sheet 2026

The 30 highest-yield 309A facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What type of transformer winding has the most turns? → The high-voltage winding always has more turns
2. What is the maximum ambient temperature rating for standard NMD90 cable insulation? → 90°C
3. What type of motor protection device uses a bimetallic element that bends when heated? → Thermal overload relay
4. What is the current flowing through a 4.7 kΩ resistor with 24 V applied across it? → 5.1 mA
5. What is the safe approach distance for a qualified electrician to work near 600V energized conductors without wearing appropriate PPE? → There is no safe approach distance without appropriate PPE
6. What material is the armour of AC90 cable typically made from? → Aluminium
7. What is the minimum length for a ground rod used as a grounding electrode according to the CEC? → 3.0 m (10 ft)
8. At what incident energy level is the threshold typically established for requiring arc-rated PPE? → 1.2 cal/cm²
9. What does a motor's nameplate 'code letter' indicate? → The locked-rotor kVA per horsepower
10. According to CEC Rule 26-710, what type of receptacle is required in a bathroom within 1 m of a sink? → Ground fault circuit interrupter (GFCI) protected receptacle
11. Which conductor insulation type is rated for both wet and dry locations at 90°C? → RW90
12. What is the typical starting current of a squirrel cage induction motor when started across-the-line (DOL)? → 300-600% of FLC
13. What does the term 'plugging' mean in motor control? → Reversing the motor connections while running to provide rapid braking
14. What is the minimum burial depth for direct-buried RW90 cable under a driveway according to the CEC? → 600 mm
15. What test is performed on a transformer to determine its core losses (iron losses)? → Open-circuit test
16. What is the purpose of paralleling transformers in a distribution system? → To increase capacity and provide redundancy
17. What is the CEC requirement for identifying conductors that have been re-identified from their original colour? → Apply tape or markers at each end and at every accessible point
18. What is the primary purpose of a Ground Fault Circuit Interrupter (GFCI)? → Protecting people from electric shock caused by ground faults
19. What happens to current flow when the resistance in a circuit is doubled while voltage remains constant? → Current is halved
20. According to the CEC, what is the minimum size of copper grounding conductor for a 200 A residential service? → No. 2 AWG
21. What determines the frequency of an AC generator's output? → The speed of rotation and number of poles
22. A 10 kW, 240 V single-phase load operates for 8 hours. How many kWh of energy are consumed? → 80 kWh
23. What type of motor starter reduces the starting current to approximately one-third of the full-voltage starting current? → Wye-delta starter
24. What is a concrete-encased grounding electrode (Ufer ground)? → A minimum 6 m of bare No. 4 AWG copper conductor encased in concrete foundation footing
25. What is the CEC requirement for tamper-resistant receptacles in dwelling units? → Required for all 15 A and 20 A receptacles
26. According to the CEC, where must GFCI protection be provided in a dwelling unit? → Bathrooms, kitchens, outdoors, garages, unfinished basements, and within 1.5 m of sinks
27. What type of cable is designated TECK90 used for in Canadian electrical installations? → Exposed industrial wiring in wet or dry locations
28. Before using a voltage tester to verify that equipment is de-energized, what must a worker do first? → Verify the tester is functioning correctly by testing it on a known energized source
29. Under the CEC, what is the maximum number of conductors permitted in a single raceway before derating factors must be applied? → 1 to 3 conductors
30. According to the CEC, in which locations is GFCI protection required in a residential installation? → In bathrooms, garages, outdoors, and unfinished basements