Why transmit high and use low
Power is voltage times current, but the losses in a cable rise with the square of the current. Push the same power at a higher voltage and the current — and therefore the loss and the conductor size — falls dramatically. That is why Kenya's grid steps up to 220kV and 400kV for transmission, distributes at 33kV and 11kV, and only drops to 415/240V at the customer transformer.
The signs you have outgrown LV
A growing industrial or commercial site eventually hits the limits of a low-voltage supply:
- the voltage sags badly at the far end of the plant when big loads run,
- KPLC capacity charges for a large LV connection become uneconomic,
- you keep tripping the main as load grows,
- you simply cannot get more LV capacity at the site.
At that point the fix is a dedicated 11kV or 33kV intake with your own transformer — which also typically unlocks a better tariff band.
Sizing the transformer (and why bigger isn't better)
A transformer has two loss streams:
- Iron (no-load) losses — present every second it is energised, magnetising the core, whether or not it serves any load.
- Copper (load) losses — rise with the square of the load current.
A transformer is most efficient where these two are roughly equal, usually around 40-60% of rating. Grossly oversizing it wastes money continuously through standing iron loss; undersizing it overheats and shortens its life. The efficiency at a load fraction x is:
η = (x·S·PF) ÷ (x·S·PF + P_iron + x²·P_cu)
For sites heavy in VFDs and rectifiers, specify a K-rated transformer built to tolerate harmonic heating, and choose the cooling class (ONAN/ONAF) for the Kenyan ambient — a unit comfortable in a European basement can run hot in a Mombasa switch-room.
Capitalised losses: the cheap transformer can be the expensive one
Over a 25-year life, a cheaper transformer with higher losses can cost far more than a low-loss unit that costs more upfront. Always compare the capitalised loss (the lifetime cost of the iron and copper losses), not just the purchase price — the same lifetime-cost logic we apply to generators and motors.
The project: more than a transformer
A proper HV intake includes the transformer, the HV switchgear and protection (graded so a fault trips the nearest device), the earthing (tested for step and touch potential), the KPLC liaison and the metering. Done right, it gives you reliable capacity for years of growth and a better tariff; done cheaply, it is a safety and reliability liability.
The bottom line
If your LV supply is sagging, tripping or capped, it is probably time for your own HV intake. The decision turns on your load growth, the tariff benefit and the transformer's lifetime losses — not just the connection cost.
Tell us your current and projected load and we will advise whether an 11kV/33kV intake makes sense, size the transformer and handle the KPLC liaison. Call +254 768 860 665 or +254 782 914 717.