Max Demand again...

[bugsy]

Connected loads will not nessacerily equate to maximum demand., I very much doubt you reach the 60a rating of the cut out

 

[blackiel]

Im with you Des, Mate...Sometimes people go too far over the top.

Lost count of the number of houses ive done over the years,but 95m2,three bedder,

3 x rings...(kit,up,down) 96a
2 lx ighting(up,down) 12a
1 x cooker (40a) 40a
1 x shower (40/50a) 40/50a
1 x smokes 6a

Split load board

shower,cooker,down+kitchen ring,outside lights.....R C D

up rin,.lights,smokes.............................Main Switch

Job Done...,(after test)

$3500 Sterling Please!!!

 

[blackiel]

Forgot....1 x Radial in kitchen.....

$3750 Sterling Please....

 

[SirKit Breaker]

I still use the equation as follows.

add all the lot together and times it by 0.4 and thats the answer.
If you think about it, you could put in lets say 2 ring finals on 32a breakers, and 2 radial lighting circuits on 6a breakers.

32+32+6+6= 76 x 0.4 =30.4

or you could put in 3 x 16a radials and on ring final x32a and 4 lighting circuits at 6a, but supplying the same amount of points as example one and you figure will be different although your maximum demand is the same.

16+16+16+32+6+6+6+6=104 x 0.4 =41.6

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

 

[JulianC]

supplying the same amount of points as example one and you figure will be different although your maximum demand is the same.

That's the crux of the matter. Obtaining a max demand figure based on the number of circuits is fundamentally flawed. It takes no account of points served or, more importantly, actual demand of the items connected to the circuits. You might as well take a complete guess, or stick the size of the cut out fuse down as your figure, or any figure in between - in a domestic situation these are probably as accurate as the overcomplicated nonsense given in the OSG. In my opinion.

 

[GStueyXR]

I had a conversation with an electrical engineer the other day over a simarlar situation.

I am in the process of wiring 2 houses being knocked into 1. No incoming Gas, so high demand. Air source heat pump + Storage tank = 32A+20A, 2 cooker circuits, 4 socket rings, 7 light circuits, smokes, and an unprotected freezer/fridge circuit.

Best I could get was 176A after diversity applied. Anyway, Engineer I spoke to said Max demand was very much guidance and not at all statutory, common sense must be applied and adding more circuits dosent increase demand, but just makes the installation safer and less prone to nuisance tripping. Gotta say, I totally agreee with him.