Diversity

[swparksey]

Having spend my life in an industrial maintenance roll I seem to have forgotten all I learned, could somebody help me on this one.

Its a new build and I am looking at the demand, where am I going wrong.

Diversity for total demand

Curcuit MCB
Upstairs Ring 32A
Downstairs Ring 32A
Lighting Upstairs 1 (5 Lights) 6A
Lighting Upstairs 2 (7 Lights) 6A
Shower 8KW 35A
Cooker Oven 7.2kw 32A
Smoke Alarms x 2 6A


So apply diversity?

Ring
100% of largest then 40% of other = 44.8A
Lighting 66% of demand (100w) = 66% 0f 5.22a = 3.45A
Shower 100% = 35A
Cooker 10A + 30% of fl in excess = 16.39A
Smokes No diversity ?? = 6A

Total demand = 105.64A and I haven't got the spec for the boiler yet

 

[ezzzekiel]

im suffering terribly from early cold, but looking at it cant see the problem?

 

[ezzzekiel]

also allows rule of thumb = full rating of largest circuit plus 40% of remainder

 

[Risteard]

The smokes will hardly use 6A.

 

[GStueyXR]

use the rule of thumb mate.... 80.6A then

 

[swparksey]

The smokes will hardly use 6A.

I know but I wasn't sure if I could use the rating of the smokes or if I had to use the MCB size?? either way which rule of thumb would that be I would ad them up and multiply by 0.4 old school making 59.6A or your way 80.6A so confused I think I may go back to the world of maintenance .

 

[GStueyXR]

total all circuits excluding largest, multiply by 40% and add the largest.

 

[swparksey]

I've got it now, thanks,

 

[mrMale31]

Hi, how do you apply the diversity to a 10 way split load board? eg 100a main switch split with 63a rcd covering 6a, 6a, 16a, 32a and 32a mcb's then a 80a rcd covering 6a, 16a, 32a, 32a and 40a mcb's. Do you apply diversity to each split load at 100% largest and 40% smallest which is 56a for the 63a rcd and 74.4a for the 80a rcd, how does the 100amp main switch calculate against these 2 figures rhen as 56a + 74.4a is over the 100amps. Or do you disregard the rcds and calculate all the mcb's together against the 100amp main switch? which is 111.2a, but then this is over the 100amps to.

Also if i was to put in a second board for garage etc, how do you calculate the diversity for each board as the mains in fuse is 100amps to, eg if i put 2 or 3 boards on that after diversity they are both within the 100amp swith on the board in theory i can run upto 200-300amps, but as the mains in fuse is only 100amps how do you calculate so you dont overload the main fuse?

 

[GStueyXR]

Mrmale, ignore te RCD ratings, that is just a breaking capacity. See my post above.