5th year peak load (commercial 30 days)

The 5th year peak of the load centre is found by growing each class's consumption to the 5th year, applying the coverage factor to the consumer number, converting daily energy to individual peak using the 5th year load factor, and adding class peaks weighted by their contribution factors.

Assumption: no population growth is given, so the number of potential consumers stays the same; growth is applied for $n = 5$ years.

Formulae

$$\begin{aligned} N_5 &= N_0 \times \text{coverage factor} \\ E_5 &= E_0 (1 + g)^5 \\ E_{day} &= \frac{E_5}{\text{effective days per month}} \\ P_{ind} &= \frac{E_{day}}{24 \times LF_5} \\ P_{class} &= N_5 \times P_{ind} \\ P_{LC} &= \sum CF_i \times P_{class,i} \end{aligned}$$

Step 1: Consumption growth multiplier

$$(1 + 0.05)^5 = 1.27628$$

Step 2: Effective number of consumers

Step 3: Consumption and individual peak demand

Sample calculation (domestic):

$$P_{ind} = \frac{1.2763}{24 \times 0.25} = \frac{1.2763}{6} = 0.21271 \text{ kW}$$

Step 4: Class peak and contribution to load centre peak

Step 5: Load centre peak

$$P_{LC} = 14.890 + 1.241 + 0.745 = 16.875 \text{ kW}$$

Note that the plain sum of class peaks (24.82 kW) would overestimate the demand by about 47%, because commercial and non-commercial loads peak at other hours.

Answer: 5th year peak load of the load centre ≈ 16.88 kW.

For transformer selection, this would be converted to kVA (e.g. at 0.85 p.f., $16.88/0.85 \approx 19.9$ kVA), plus a loss allowance, so a standard 25 kVA transformer would be suitable.