Maximum demand on EICR

NICEIC Technical Helpline have replied, probably quite rightly, that they cannot make comment other than to say the maximum demand box now appears in section J of the EICR in BS7671 A4.

I have 24 candidates going through the 2391. I rarely offer my opinion to candidates, preferring instead to give only guidance on the relevant requirements of BS7671 and GN3. However, since I have not been able to establish the rationale for including a box for maximum demand, I have suggested that for the purposes of their practical assessment, during which an EICR is to be completed, they simply insert “not verified” in that box. I have also suggested that as they move out into the real world, they keep their eye on any developments in that regard.

Noteworthy that the example EICR in GN3 indicates a figure of 80A but does not indicate how this was arrived at.

As an exercise in my 2396 class, we used all available resources we could find, including the EIDG and data logger information, to assess the maximum demand for the circuit arrangements in my own house. At least I know it sits somewhere between 27A and 118A.

lyledunn said:

Noteworthy that the example EICR in GN3 indicates a figure of 80A but does not indicate how this was arrived at.

Nor the 50 A in the three-phase installation on page 148 of 10th Edn.

Here in SSEN territory, I understand that the usual agreed (i.e. imposed) after diversity maximum demand for a new single-phase installation is 18 kVA, which is about 80 A.

Frankly, with socket-outlets, it is impossible to know what the maximum load might be.

lyledunn said:

Noteworthy that the example EICR in GN3 indicates a figure of 80A but does not indicate how this was arrived at.

Nor the 50 A in the three-phase installation on page 148 of 10th Edn.

Here in SSEN territory, I understand that the usual agreed (i.e. imposed) after diversity maximum demand for a new single-phase installation is 18 kVA, which is about 80 A.

Frankly, with socket-outlets, it is impossible to know what the maximum load might be.

Chris Pearson said:

Frankly, with socket-outlets, it is impossible to know what the maximum load might be.

But you need to have some working assumption - otherwise it would be impossible to design a circuit to supply the sockets.

The traditional UK approach was floor area served - 30A per 1000ft² (or 32A per 100m²) as an upper bound for most domestic and small commercial seems to have stood the test of time, and of course the size of the protective device sets an upper limit too. The trick of course with MD is to view the installation in terms of the minimum circuits that could have been provided, rather than the usually much larger number of circuits that have been installed.

   - Andy.