Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This one, concerning conversion of a large building into flats and the calculated maximum demand, is answered by SELECT:
The following is the electrical equipment that will be going into the one-bed flats of which there are two:
1 no lighting circuit - 4 lights max
2 no ring mains - 5 sockets on each ring main
1 no cooker circuit single 13A oven and electric hob
1 no. 7kW shower
1 no. 8kW instantaneous water heater
…plus 5kW of convector heating, probably on two circuits.
Studios of which there are four:
1 no lighting circuit - 3 lights max
1 no ring mains - 7 sockets on ring main
1 no cooker circuit single 13A oven and electric hob
1 no. 7kW shower
1 no. 8kW instantaneous water heater
…plus 3kW of convector heating, probably on one circuit.
And bedsits with no kitchen, of which there are two:
1 no lighting circuit - 2 lights max
1 no ring mains - 4 sockets on ring main
1 no. 7kW shower
1 no. 3kW water heater
…plus 2kW of convector heating, probably on one circuit.
The landlord's supply:
1 lighting circuit 4x 28W 2D fittings
1 radial for fire alarm
1 radial for socket
1 ring main for comm. kitchen
1 cooker circuit with socket
3kW of convector heating
I have calculated these and applied diversity - EDF thinks that the figures are high. Please help!
Answer: Appendix 1 of the IEE On-Site Guide, and Appendix H of IEE Guidance Note 1, give guidance on the calculation of maximum demand for individual installations. They do not, however, give guidance on blocks of residential buildings, for example and explain that allowances for such installations need to be carried out by a competent person.
If you have followed the guidance in these guides for the individual flats, the distributor should then use that information to make allowances for the building as a whole.
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