Max Demand Calcs

[chloebear]

Hi All,

Just wondering if anyone can help with calculating the Max emand for the following - I have carried out my own calcs in three different ways and keep coming up with a very high figure. This installation will be single phase and run off a sub main U/G cable.

4x 58W strip lights
8x Downlights (50W)
5x External Security Lights (300W each)

1x Ring

2x Instantanious Water Heaters (9.5Kw each)
2x Storage Heaters (3.4Kw each)
1x Underfloor Heating (2.5Kw)
2x Heaters (6.5Kw each)

It all looks Ok until you get to the haeters etc then it looks like you need your own sub station to power it. I keep coming up with a figure around 170 to 180 amps - around 40Kw ish.

 

[Notsosmart]

Maximum demand can be a bit subjective (even if the OSG does give some 'Guidance' on the subject)

Basically through knowledge of the installation and its use you can make a call on the potential maximum demand that could actually transpire ~ however a note of caution; get it wrong and potentially expensive retrospective work will need to be carried out ie utilising a 3 phase supply the extra work and materials required.

Ask yourself;
How often are the instantaneous water heaters going to be used
When are the storage heaters drawing most current (is it when hardly any other equipment is used)
How often (and for how long) are the security lights going to be on.

Etc..

 

[bugsy]

Hi All,

Just wondering if anyone can help with calculating the Max emand for the following - I have carried out my own calcs in three different ways and keep coming up with a very high figure. This installation will be single phase and run off a sub main U/G cable.

4x 58W strip lights
8x Downlights (50W)
5x External Security Lights (300W each)

1x Ring

2x Instantanious Water Heaters (9.5Kw each)
2x Storage Heaters (3.4Kw each)
1x Underfloor Heating (2.5Kw)
2x Heaters (6.5Kw each)

It all looks Ok until you get to the haeters etc then it looks like you need your own sub station to power it. I keep coming up with a figure around 170 to 180 amps - around 40Kw ish.

2 x 58w, 116w, 2 x 29w, 4 x 50w , 200w 300w 150w, 9500w , 4750w, 3400w, 1700w, 6500w 4500w

135a ( based on supply voltage of 230 ) what are the 6.5 kw heaters,