Maximum demand

[trainee31]

Its my first time working out the maximum demand in my house, can someone help me figure this out?
I have have:-

Kitchen RFC with 4 sockets (no cooker as its gas) So is that 100% = 32A?
RFC down stairs (7 sockets) - Is that 40% of 32A= 12.8?
RFC up stairs (10 sockets) - 40% of 32A= 12.8
RFC garage (5 sockets) - 12.8

Lights up stairs (16 most are 35w GU10 lamps)
Lights down circuit 1 stairs (16 most are 35w GU10 lamps)
Lights down circuit 2 stairs (all are 11w energy saver lamps)
So is that 66% of 6Amps x3?

Total 82.28Amps

I have a 60A main fuse, 25mm tails and 100A main ccu switch.

 

[flameport]

If the OSG is to be believed, then those are the kind of figures you will get.

More significant is how the building will actually be used.
32A in a kitchen - possible but not for any length of time.
12A in a garage? A total of 26A upstairs and down? Unlikely.

Consider that most modern appliances in rooms other than the kitchen use very little power. Hence the usual multiple extension leads all connected to each other, yet the 13A fuse at the end never blows.

Also consider that no so long ago, one 32A circuit was used for all of the sockets in a house. If that same house is rewired with 3x 32A circuits for the sockets, does this mean the total load has increased?

 

[riveralt]

You will need to use the formula - you can find it in BS7671.

 

[holmslaw]

..

 

[westie101]

Just as a learning curve

Can anyone tell me the average maximum demand (ADMD) the DNO would see from this house?

 

[riveralt]

You will need to use the formula - you can find it in BS7671.

there is no formula the figure is 14kw unless you happen to live in buckingham palace.

Terribly sorry there holmshaw I meant to say the OSG for 17th edition of BS7671 - things like applying 100w per lamp etc.

But I am intrigued how you get 14kw or indeed why you get 14kw when max demand is measured in Amps

or do you mean 60.87 Amps.

 

[flameport]

Can anyone tell me the average maximum demand (ADMD) the DNO would see from this house?

2kW or some similar low figure ?

 

[westie101]

2kW or some similar low figure

Yep

 

[riveralt]

Its my first time working out the maximum demand in my house, can someone help me figure this out?
........
Lights up stairs (16 most are 35w GU10 lamps)
Lights down circuit 1 stairs (16 most are 35w GU10 lamps)
Lights down circuit 2 stairs (all are 11w energy saver lamps)
So is that 66% of 6Amps x3?

Total 82.28Amps

For lights use the formula given in the OSG that is current equivalent to the connected load, with a min of 100w per lampholder then apply diversity.

So say all three lighting circuits have 16 lights per circuit (you don't say how many for LC 2) then 1600w/230v = 4.6Amps (after diversity)

Add this to your other circuits and you get a total of 84.2Amps. I take it you don't have an electric shower.

I have a 60A main fuse, 25mm tails and 100A main ccu switch.

You could ask the DNO to increase the size of your main fuse, I think the max is 100Amps. Alternatively, you could replace the ring final circuit with radials of 20Amps (bringing it down to 57.8Amps) or have one ring final circuit and the others radials.

Thing is as flameport said, are you ever going to draw 13.8kw of power in one go - unlikely.

 

[Stoday]

Can anyone tell me the average maximum demand (ADMD) the DNO would see from this house?

According to data from Elexon, the Balancing & Settlement Code company, the average consumption of an unrestricted domestic cionsumer is 4079kWh leading to a maximum demand of 1.16kW at the BSP (equivalent to the DNO's connection to the National Grid).

From this DNOs would typically estimate the extra demand on their 11kV system from an average unrestricted domestic consumer to be 1.4kW; on their 11kV/LV substation, 2.25kW; on their LV feeder, 3.6kW; on the household's meter, 5.8kW. The variation of demand with system voltage level is a consequence of diversity with demands from other consumers, especially non-domestic.

At first, 5.8kW would appear inconsistent with a typical household demand of 18kW. However, the DNO's MD is defined as twice the maximum number of kWh consumed in any half hour period, i.e. the demand is averaged over a half hour. That "integration period" is appropriate for the size of plant and cables on a distribution system, but not for a consumer's installation. The latter is nearer to an instantaneous MD but excluding short transients such as small motor starting transients.

 

[ColJack]

I was told that they allow(ed) 16A per house when designing the electrical requirements of a planned development..
I don't know if that figure has been uprated in recent times to allow for the increased use of electric appliances such as cookers and showers, that were not so common in the past.