Maximum Demand Calculation

[SPECIAL LOCATION]

Never mind about diversity. The installation with a 100A fuse can draw no more than 100A so therefore 100A is the maximum demand.

Incorrect. peaks and surges can far exceed 100A through a 100A cartridge fuse.

It most certainly is not going to pop the minute it reaches 101Amps!

AND!!!

what if the fuse is not there yet!?

New build... new supply...

You design the installation to be able to carry certain loads,

then request a supply from the DNO that can support your maximum demand.

Appendix 1 of On-Site Guide pages 95 - 97

AND

Appendix H of guidance note 1 pages 177 - 179

AND

Regulation 311.1 of BS7671 page 38

would all be worded differently and/or be a lot shorter if it was just a simple write the cut-out fuse rating.

You have to ensure that your additions and alteration do not create a max demand that exceeds the cut out rating..

what about older properties with just 80A or 60A cut out..

add a few extra high power appliances and the maximum demand can quite easily exceed the cut out..

No good saying oh the cut out is 80A so installation with never draw more than the cut-outs 80A rating...

Because without the ability to assess maximum demand you will have no idea if your main fuse is likely to pop..

 

[sparkytim]

I agree

the whole exercise is for YOU to assess the demand and ensure an adequate supply is available

i.e. You put a 10.5 KW shower in then YOU must get supply upgraded to suit

 

[ITS]

Specs - you are fantastic. I'm becoming a fan.