Total load + diversity

[mhar]

Is there any diversity re overnight circuits when calculating total load. I can see that for shift workers it could be possible to have a shower whilst someone is cooking a roast whilst the storage heaters are demanding juice but.....

 

[SirKit Breaker]

No mate, there is diversity, and that is it. Dont read too much into diversity, it is overrated. The simple maths is, add up all the values of your fuses and breakers or whatever, then multiply it by 0.4. This is near enough for calculating maximum demand. The chances of actually achieving maximum demand, are about the same as winning the lottery.
Where all this diversity stiff goes pear shaped is this. Lets imagine a 3 bed semi, 2 x 5a lighting circuits, 2 x 32a ring finals. 5+5+32+32x0.4= 29.6a. You rewire it, and split things up a bit, same amount of lights, and same amount of sockets, but you put 4 lighting circuits in, and a 16a radial to each room (7 in total), all 60898 MCB's.
6+6+6+6+16+16+16+16+16+16+16 X 0.4 = 54.4a.

So your maximum demand has changed, but nothing else has.

Cheers...........Howard

 

[mhar]

Thanks, don't really see how you can multiply overnight circuits by .4 though. Say an overnight cu with 5 x 16A 60898's, when the magic hour comes you know that they will be close to maximum demand so not far off 80A with the demand only dropping after an hour or so as cylinders etc reach temperature. To my mind this is a given so pretending it is only 32A (80x.4) doesn't feel right. Just one of those things that I have to accept?

 

[Brightspark2]

I once read 0.4 for houses, 0.6 for commercial and 0.8 for industrial....IIRC


You'd be surprised at what actually takes FLC...even in the sitution your describeing its doubtfull it would be taking 32A, thats a lot of power considering.

 

[Guitarist]

When working out demand for new housing, the "powers that be" allow 13amps per house on average at any one time. Now that is diversity.