Finding the best generators for your construction portable office rental takes more than just hooking one up and turning it on. Selecting a generator that is not sized correctly can lead to annoying circuit breaker trips, equipment not functioning correctly and undue wear and tear on the generator itself.
If you choose a generator that is undersized you may have no trouble turning on the lights or charging your cell phone, but you’ll likely trip the generator circuit breaker if you try to turn on the heater or air conditioner.
If you choose a generator that is too oversized, it can damage the generator. Running generators at low loads for long periods leads to increased maintenance costs.
We’re often asked what generators are best for portable offices used on construction sites. In this post, you’ll learn how to figure out your wattage and what to look for when choosing from the different generator options.
Calculating Power for Your Generator
When considering generator power, you need to know the wattage of all the equipment used inside your portable office, including HVAC units, lighting, computers, printers, TVs and coffee machines.
Most devices will list either their total wattage or their amperage and voltage. Add up the total wattage of each product that will be powered by the generator to figure out how much generator power you need.
If you only know the amps and volts of your equipment, multiply amps by volts to get the wattage.
When you rent one of our portable offices, we will recommend a generator wattage size for the office you select, if requested. This will help narrow down your generator choices.
Choosing the Right Sized Generator for a Portable Office Rental
Your construction project will dictate which portable office rental you’ll need, which will in turn help to determine the size of the generator. For our portable offices, you may use a portable generator between 3 kW and 10 kW or a trailer mounted generator between 10 kW and 30 kW, depending on the office and your needs.
In general, generators shouldn’t be operated for more than 30 minutes at maximum power. However, if you plan on using it as a main power source for your construction site, the generator should be a size that can operate within 70-80% capacity, which will help with overall performance and allows for any further power requirements.
Fuel sources for generators can include diesel, gas, and even solar power. Be sure to check any regulation or compliance measures for using a particular fuel source.
Watch the video below to learn about some of the best portable generators for jobsites.

Choosing the best generator for your portable office rental doesn’t need to be a challenge and being aware of what your total wattage is for all the devices you’ll be using goes a long way in picking the right generator to power your construction site.
Now that you know more about choosing the right generator, learn more about keeping your items and construction storage containers safe from site theft with our ultimate guide to storage container security.