PART P Cheat Sheet 2026

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

1. What colour is the standard outer sheath of twin and earth cable used in UK domestic fixed wiring? → Grey
2. According to BS 7671 18th Edition, what is the maximum disconnection time for a 230V final circuit not exceeding 32A protected by an overcurrent device? → 0.4 seconds
3. During an RCD test, what trip times are acceptable for a 30mA Type AC RCD when tested at rated residual current (IΔn)? → Must trip within 300ms
4. Which of the following is NOT notifiable work under Part P? → Replacing a like-for-like socket outlet on an existing circuit in a living room
5. What is the 'rated current' (In) of an MCB? → The maximum continuous current the MCB can carry without tripping
6. What is the maximum floor area that can be served by a single 32 A ring main circuit in a domestic dwelling? → 100 m² (any floor, or individual floors above 100 m² require additional circuits)
7. What does a Periodic Inspection Report (PIR/EICR) code C2 signify? → Potentially dangerous — urgent remedial action required
8. What is a 'periodic inspection report' now called? → Electrical Installation Condition Report (EICR)
9. What is the purpose of discrimination between protective devices? → To ensure only the device closest to the fault operates, leaving other circuits unaffected
10. What does 'Zs' represent in electrical installation testing? → The total earth fault loop impedance of the circuit
11. What instrument is used to measure the resistance of an earth electrode? → An earth electrode resistance tester (using the 3-probe or 4-probe method)
12. What is Zone 0 in a bathroom? → The interior of the bath or shower tray itself — the area always in contact with water
13. What size bonding conductor is required for supplementary bonding between two extraneous-conductive-parts (e.g., two metal pipes)? → 2.5mm² if mechanically protected, 4mm² if not
14. According to BS 7671 Section 701, what is the extent of Zone 1 in a bathroom with a bath? → The area directly above the bath tub to a height of 2.25m from the floor
15. According to BS 7671 Section 722, what additional protection is required for EV charging installations in domestic properties? → 30mA RCD protection, and depending on the charger type, a Type A or Type B RCD
16. What standard specifies requirements for consumer units in domestic installations? → BS EN 61439-3 (consumer units for household and similar applications)
17. What Type of MCB is most commonly used for a ring main circuit in a domestic installation? → Type B 32 A MCB
18. Part P applies to electrical installations in which type of building? → Dwellings and their associated gardens, outbuildings and shared amenities
19. Which edition of the IET Wiring Regulations (BS 7671) is the current standard referenced by Part P? → 18th Edition (Amendment 2)
20. Which of the following is NOT a recognised competent person scheme for self-certification of electrical work under Part P? → City & Guilds
21. What is the minimum cross-sectional area of the earthing conductor connecting the MET to the earth electrode in a TT system? → 6mm² copper if mechanically protected, 16mm² if not
22. When testing the continuity of a ring final circuit, what is the expected result at the socket furthest from the consumer unit? → Approximately 25% of the end-to-end resistance (r1 + r2)/4
23. How does the zone apply in a bathroom where the ceiling height is less than 2.25 m? → Zone 1 extends to the ceiling regardless of whether the ceiling height is below 2.25 m
24. What is the maximum continuous conductor operating temperature for standard PVC insulated and sheathed cables (e.g., twin and earth)? → 70°C
25. What is the recommended EICR interval for a privately rented domestic property? → Every 5 years or at each change of tenancy
26. What is the minimum cross-sectional area of a supplementary bonding conductor between two exposed conductive parts? → 2.5 mm² if mechanically protected, 4 mm² if not mechanically protected
27. Following the 2004 harmonisation with European cable colour standards, what colour is the line conductor in UK fixed wiring? → Brown
28. What type of RCD detects both AC and pulsating DC residual currents? → Type A RCD
29. What is the recommended minimum burial depth for a cable installed under a domestic garden or lawn (not subject to vehicle traffic)? → 500 mm
30. What is the minimum IP rating for electrical equipment installed outdoors in a domestic garden? → IPX4 (splash-proof) minimum, with higher ratings where directly exposed to rain