ECS Cheat Sheet 2026

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

1. Which cable type is specifically rated for direct burial underground installation? → UF-B (Underground Feeder)
2. Which of the following is an acceptable method for supporting horizontal cable runs in a commercial installation? → Cable tray with appropriate supports at specified intervals
3. What safety feature on a power tool prevents it from starting accidentally if it is dropped or the trigger is bumped? → Trigger lock-off or safety guard on the trigger
4. In accordance with the Electricity at Work regulations, when considering whether to work live a responsible person should: → Carry out a risk assessment
5. What is the primary purpose of earthing (grounding) in an electrical installation? → To provide a safe fault current path and facilitate overcurrent device operation
6. What is the most serious effect that electric shock can have if you come into contact with a live part? → The electric current can cause the heart to stop, resulting in death
7. Which factor is most critical when selecting a cable for a specific application? → The cable's current-carrying capacity, voltage rating, and environmental suitability
8. When securing a point of isolation, what is the primary purpose of using a unique padlock and key kept by the person carrying out the work? → To ensure that only the competent person working on the circuit can re-energise it.
9. When cable tray is used as a cable support system, what is the maximum recommended fill ratio? → Around 50% to allow heat dissipation and future additions
10. What is the standard frequency of the electrical supply in the United States? → 60 Hz
11. What is the minimum bending radius typically required for PVC-insulated cables to prevent damage to the insulation? → 6 times the overall cable diameter
12. Which conductor color represents the live (line) wire in a standard US electrical installation? → Black or red
13. What minimum clearance is typically required between power cables and communication cables when run in parallel? → At least 50mm (2 inches) to reduce electromagnetic interference
14. Which cable installation method requires the installer to check for 'short-circuit withstand' in addition to current-carrying capacity? → Cables protected by fuses or circuit breakers where fault currents could be very high
15. What does AWG stand for in the context of electrical cable sizing? → American Wire Gauge
16. What does the HSE Guidance Note GS38 primarily provide guidance on? → The selection and use of electrical test equipment for use on low-voltage systems.
17. What is the primary purpose of a main distribution board (MDB) in an electrical installation? → To distribute power to sub-circuits and provide overcurrent protection
18. What is the function of a cable gland in an electrical installation? → To provide a secure, sealed entry point where a cable enters an enclosure
19. When using an angle grinder on site, which PPE item is most critical in addition to standard safety equipment? → A full face shield to protect against flying sparks and disc fragments
20. A portable electric generator on site has two power outlets, 110 volts and 230 volts. What colour would the 110-volt outlet be? → Yellow
21. Why are cables sometimes installed with armoring in electrotechnical work? → To protect against physical damage in industrial or hazardous environments
22. Which insulation material is commonly used for cables installed in wet or damp locations? → Cross-linked polyethylene (XLPE) or similar moisture-resistant insulation
23. What instrument is used to test the continuity of a protective earth conductor? → Low-resistance ohmmeter or continuity tester
24. What color is the protective earth conductor required to be in a fixed electrical installation? → Green and yellow stripes
25. What is the primary reason for balancing loads across the three phases of a three-phase distribution system? → To minimize neutral current and prevent overheating of the neutral conductor
26. What is the purpose of a sub-distribution board (SDB) in a large commercial electrical installation? → To distribute power locally within a zone, fed from the main distribution board
27. What does the term 'demand factor' refer to in electrical distribution planning? → The ratio of maximum demand to the total connected load
28. When installing cables in a wall, what is the primary reason for using a cable detection tool before drilling? → To locate hidden electrical cables and avoid electrocution
29. What is the primary legal purpose of an employer maintaining an accident book for a business with 15 employees? → To provide a legal record of work-related incidents for compliance and potential claims.
30. How should cables be identified in a multi-circuit electrical installation? → Using color-coded insulation and circuit labels or tags