Power Consumption Chart

This chart is provided as an example as to how wattage varies between various electrical devices.

Open PDF Chart

Standard Electrical Formulas Used for Power Consumption Calculations

It is not meant to be a strict guide to calculate your requirements.  For the most accurate calculations refer to the owner’s manual of each device, tool, appliance, etc., or most preferably, consult a professional electrician:

Starting vs. Running Wattage: Why It Matters for Commercial Generator Sizing

When you’re sizing a generator for a commercial operation—say, a construction site, retail store, or medical facility—getting the power calculations right is critical. One of the trickiest parts? Understanding the difference between starting wattage and running wattage. These two numbers can make or break your generator’s performance, and mixing them up could leave you in the dark when you need power most.

What’s the Difference?

Running wattage is the steady power an appliance or tool needs to keep operating. It’s the baseline—think of a circular saw humming along at 1200 watts once it’s spinning. Starting wattage, on the other hand, is the extra juice required to get that device going. That same saw might demand 2400 watts for a split second to overcome inertia and kick into gear. For some equipment, like air compressors or water pumps, starting wattage can be two to three times higher than running wattage due to the heavy initial load.

In commercial settings, this distinction is a big deal. Facilities often run multiple devices with high starting demands—think HVAC systems, industrial motors, or refrigeration units. If your generator can’t handle those startup surges, you’ll face tripped breakers, stalled equipment, or even generator failure.

Why It Matters for Sizing

Choosing a generator based only on running wattage is a rookie mistake. You need to account for the highest starting wattage in your lineup, plus the running wattage of everything else that’ll be on at the same time. For example, a construction site firing up a 4000-watt disc grinder (2000 running) while keeping lights and a water pump (1000 running) online needs a generator that can handle at least 5000 watts at peak, if not more, to avoid overloading.

This is especially crucial for businesses where uptime is non-negotiable. A hospital can’t afford a generator that chokes when an MRI machine starts. A data center needs enough surge capacity to boot servers without blinking. Undersizing your generator risks costly downtime, equipment damage, or safety hazards like voltage dips that fry sensitive electronics.

Tips for Getting It Right

1. List Everything: Catalog all devices your generator will power, noting both starting and running wattages. Check manuals or nameplates for exact figures, as estimates can be off.
2. Plan for Peaks: Add up the highest starting wattage plus the running wattages of other devices. This gives you the minimum generator capacity needed.
3. Add a Buffer: Aim for a generator with 20–30% extra capacity to handle unexpected surges or future expansions.
4. Consult a Pro: For complex setups, an electrician can measure real-time loads and ensure compliance with codes like the National Electrical Code (NEC).

By mastering starting vs. running wattage, you’re not just buying a generator—you’re investing in reliability. Use tools like our power consumption chart to get a head start, but always verify with precise data to keep your operation humming.

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