In most electric boiler installations in a thermal power plant, the available amperage is a major challenge. For industrial installations, the standard is to have a three-phase network with a voltage of 600 V in Canada or 460 V in the United States.
Enter the boiler power and the available voltage: the calculator returns the full-load current. Power can be entered either in kilowatts or in boiler hp.
Electric boiler amperage calculator
A = P(W) ÷ (1.732 × V) · 1 hp = 10 kW · at 600 V: A ≈ kW
Three-phase supply, resistive load. The figure is the full-load current: overcurrent protection and conductor sizing are governed by the electrical code and are your electrician’s call.
Amperage Calculation
The formula to calculate the amperage in a three-phase circuit is as follows:
Amps (A) = Power (W) / (1.732 x Voltage (V))
For a voltage of 600 V, you can quickly estimate the required amperage based on the power using this simplified formula:
Amps (A) = Power (kW)
For example, a 100 hp boiler (1,000 kW) on a 600 V supply needs roughly 1,000 amperes — 962 A by exact calculation.
Click here to learn more about converting hp to kW.
Amperage, kVA and sizing the supply
An electric boiler is an essentially resistive load: its power factor sits close to 1, so its apparent power in kVA is practically equal to its active power in kW. A 1,000 kW boiler draws roughly 1,000 kVA from the transformer, at 962 A on 600 V. That is what makes the sizing predictable, and also what makes it unforgiving: there is no headroom to recover through power factor correction.
The current calculated above is a full-load current. Overcurrent protection and conductor sizing follow from it under the applicable electrical code and are your electrician’s call — they are always above this figure.
Infrastructure Challenges
One recurring challenge is the availability of this amperage and the necessary infrastructure to deliver this current to the boiler’s control panel. These constraints often limit the capacity of standard electric boilers in a facility.
Alternatives for Higher Voltages
To overcome these limitations, it is essential to consider higher voltages. In North America, the voltages available beyond 600 V include:
- 4.16 kV
- 6.6 kV
- 14 kV
- 25 kV
The graph below illustrates the relationships between the different voltages, the capacities of the boilers, and the required amperage:
Technologies According to Voltage
Electric boiler technologies vary according to voltage:
- Immersion heater technology (or heating elements) is used in low and medium voltages below 6.6 kV
- Immersed electrode or jet technology is found in voltages above 600 V
For more details, please refer to the technical bulletin on electric boiler technologies.
Additional Resources:
- Technical bulletin on types of electric boilers (coming soon)
- Technical bulletin on the conversion of hp to kW