On a construction site, electricity is an essential resource: tools, lighting, compressors, temporary heating—everything depends on a reliable power source. However, not all sites have access to the electrical grid. That’s where a generator comes in. But how do you choose the right model for your needs? Here’s a complete guide to help you make the right choice.
1. Determine what you need to power
Before talking about wattage, voltage, or amperage, start by making a full list of all the equipment that will be connected to the generator. This allows you to clearly understand your actual electrical needs. Common examples on a job site:
- Power tools: drills, saws, grinders
- Pumps and compressors
- Cranes and hoists
- Temporary heating or heating cables
- Job site lighting
- Site trailers
💡 LOU-TEC Tip: Each device has a nameplate indicating:
- Voltage (V)
- Amperage (A)
- Power (W or kW)
This information is essential to properly determine the generator you will need.
2. How much power do you need?
Power corresponds to the amount of electricity required to operate your equipment and is expressed in watts (W), kilowatts (kW), or sometimes kVA.
How to calculate it:
- Add up the power (in watts) of all the devices you will use at the same time.
- Add a safety margin of 20 to 25% to account for startup surges and avoid overloads.
Example:
- 1 concrete mixer: 2,500 W
- 3 job site lamps: 3 × 500 W = 1,500 W
- 1 compressor: 3,000 W
Total: 7,000 W = 7 kW
Adding 25% → 7,000 × 1.25 ≈ 8,750 W ≈ 9 kW
➡️ You would therefore need a generator of approximately 9 kW.
💡 LOU-TEC Advice: Always choose a bit more power than the minimum calculated to ensure optimal operation.
3. What voltage should you choose?
Voltage is expressed in Volts or VAC (Volts in alternating current). Voltage (V) indicates the “strength” of the current circulating in the circuit. Amperage (A) is the “pressure” that pushes the electrical current through the cables. The choice depends on your most demanding equipment.
Examples:
- 120 V: light tools and small devices
- 240 V: compressors, pumps, heaters
- 600 V: industrial equipment, cranes, pumping stations (three-phase)
4. How many amps do you need?
Amperage (A) measures the intensity of the electrical current flowing through a circuit—in other words, the volume of electricity your equipment will draw from the generator.
- Too many amps: overload (risk of tripping or overheating)
- Not enough amps: insufficient power
Example: industrial site
- Pump: 10 kW
- Crane: 25 kW
- Lamps: 2 kW
Total = 37 kW, voltage = 600 V three-phase
➡️ Plan for a minimum of 40 A, with a safety margin of 10–20%.
5. What is the distance between the generator and the connection point?
The distance in feet between the generator and the connection point affects the cable size required and potential electrical losses. The greater the distance, the larger the cable capacity must be.
Example:
A 100 kW generator (600 V three-phase) located 250 feet from the distribution panel.
- If the cable is too small, voltage may drop to 580 V, resulting in lower power and possible equipment damage.
💡 LOU-TEC Solution:
Our technicians calculate voltage drop and recommend the proper cable and generator. Contact your representative to learn more.
Choosing the right generator is an investment in the safety, reliability, and productivity of your job site. Evaluate your real needs, consider power, voltage, amperage, and connection distance. With the right generator, you can work efficiently—even far from the electrical grid.
Of course, our team of specialists is available to help you choose the generator best suited to your job site and ensure a safe installation.
To learn more about the different generator models available at LOU-TEC, click here.
To use the LOU-TEC energy calculator, open the “Energy Calculation” tab at the link here.
📞 Contact our experts for more information: 1 866 4-LOU-TEC (ask for the Energy division)