BS7671 Part 3 Chapter 31 Purpose, Supplies and Structure
311 Maximum Demand and Diversity
Regulation 311.1 …….. In determining the maximum demand of an installation diversity may be taken into account.
What this means is that not everything will be switched on at the same time and we can make allowances for that.
Domestic installations:
Applying diversity to the maximum load (Amps)
Lighting: 66%
Heating: 100% of total up to 10A and 50% of all above
Cooking: 10A + 30% of cooker full load above 10A and + 5A if there is a cooker socket
Water Heaters: (Instant – eg. showers) 100% of largest + 100% second largest + 25% of remaining
Water Heaters: (Immersion cylinder) 100%
Floor: 100%
Storage Heaters: 100%
Sockets: 100% of largest appliance + 40% at every other point
Figures used are from the On-Site Guide which is free for all students who enrol on our 17th Edition online course.