In another thread (click here) , there has been extensive discussion about the estimated ‘maximum demand’ of a domestic electrical installation and the associated concepts of diversity. It has been pointed out in that discussion that real-world ‘maximum demands’ are usually surprisingly low.
To illustrate this, I present here some data relating to the last ~2.5 years (about 1.35 million minutes) of my electrical installation. Although data is captured roughly 5 times per minutes, I have it recorded as averages over each 1-minute period, and it is those 1-minute averages which are presented here.
It has to be said that it is a very atypical domestic property. Although now usually only occupied by two people, it is very large, with a 3 x 80A electricity supply and about 30 final circuits. There are no large electrical cooking appliances (only microwave, fat fryer, bread maker, toaster etc.) and the two electric showers are virtually never used. There is, however, a silly number of refrigeration devices! Something like one third of the total electrical consumption results from nocturnal hot water heating.
The first graph below shows the distribution of the instantaneous (1 minute) total demand, indicating that for the vast majority of periods the total demand is under about 5A. The small peak around 15-16A relates to periods when the 3kW immersion is the main load.
The second graph shows the same data, but in terms of cumulative figures, indicating that some 80% of all minutes have a demand below about 4A, about 92% of all minutes have a demand below about 14A and about 98% of all minutes have a demand below about 20A.
The final three graphs are ‘inverted’ versions of the second, the final two being ‘magnified versions’ which show what happens at the extreme tail (moments of highest demand). These show that only about 1% of minutes have a total demand >24A, and only about 0.01% of minutes (about 1 minute every week) have a demand >32A.
Over all the ~1.35 million minutes observed, the mean total demand was 4.35A and the median 2.97A. The lowest demand was 0.35A and the highest 40.36A. Summarising the number/percentage of minutes with total demands above a certain figure. As can be seen, under 2% of minutes had total demands >20A, and almost none had total demands above 30A. For about half of all minutes, total demand was under 3A.
... and here the graphs ...
As above, I don’t pretend that my house is typical, but these figures give some idea, and will undoubtedly surprise some people.
Kind Regards, John
To illustrate this, I present here some data relating to the last ~2.5 years (about 1.35 million minutes) of my electrical installation. Although data is captured roughly 5 times per minutes, I have it recorded as averages over each 1-minute period, and it is those 1-minute averages which are presented here.
It has to be said that it is a very atypical domestic property. Although now usually only occupied by two people, it is very large, with a 3 x 80A electricity supply and about 30 final circuits. There are no large electrical cooking appliances (only microwave, fat fryer, bread maker, toaster etc.) and the two electric showers are virtually never used. There is, however, a silly number of refrigeration devices! Something like one third of the total electrical consumption results from nocturnal hot water heating.
The first graph below shows the distribution of the instantaneous (1 minute) total demand, indicating that for the vast majority of periods the total demand is under about 5A. The small peak around 15-16A relates to periods when the 3kW immersion is the main load.
The second graph shows the same data, but in terms of cumulative figures, indicating that some 80% of all minutes have a demand below about 4A, about 92% of all minutes have a demand below about 14A and about 98% of all minutes have a demand below about 20A.
The final three graphs are ‘inverted’ versions of the second, the final two being ‘magnified versions’ which show what happens at the extreme tail (moments of highest demand). These show that only about 1% of minutes have a total demand >24A, and only about 0.01% of minutes (about 1 minute every week) have a demand >32A.
Over all the ~1.35 million minutes observed, the mean total demand was 4.35A and the median 2.97A. The lowest demand was 0.35A and the highest 40.36A. Summarising the number/percentage of minutes with total demands above a certain figure. As can be seen, under 2% of minutes had total demands >20A, and almost none had total demands above 30A. For about half of all minutes, total demand was under 3A.
... and here the graphs ...
As above, I don’t pretend that my house is typical, but these figures give some idea, and will undoubtedly surprise some people.
Kind Regards, John
