I’ve spent the better part of 12 years standing behind a hire counter, and there is one conversation I have at least three times a week that always goes the same way. A customer calls up, stressed, saying, "Mate, I need a generator for a job/event/reno, just give me the biggest one you’ve got."
Nine times out of ten, they end up overpaying for a massive diesel beast they don't need, or worse, they hire something too small and end up back at the yard by midday because their angle grinder keeps tripping the breaker. Before you pick up the phone to chat with the crew at places like Wenbro Hire or your local equipment depot, take ten minutes to build a proper wattage list. It saves you money, saves me a headache, and ensures your project actually gets done.
Understanding the Basics: Running vs. Starting Watts
The most common mistake people make is looking at the "running" watts on a sticker and thinking that’s the end of the story. If you’re running a fridge, a compressor, or any tool with a motor, you are dealing with inductive loads. These things require a "kick" to get moving.
Think of it like pushing a car. It takes a massive effort to get it rolling from a standstill, but once it’s moving, you can keep it going with one hand. Generators are the same. That initial surge is your Starting Wattage (or peak wattage). If your generator can’t handle that initial spike, the machine will stall, or worse, damage the electronics you’re trying to power.
The Appliance Wattage List: Your Cheat Sheet
Before you call the yard, grab a piece of paper or open a spreadsheet. You need to identify every piece of equipment you plan to plug in. For those interested in the technical side of energy efficiency and grid safety, the Australian Government Department of Climate Change, Energy, the Environment and Water (DCCEEW) provides some great resources on how appliances draw power, but for site work, use this general rule of thumb.
Equipment/Tool Running Watts (Approx) Starting (Surge) Watts Angle Grinder (9-inch) 2,000 4,000 Portable Fridge/Freezer 150 600 Pressure Washer 1,200 2,500 Hammer Drill 800 1,600 Flood Lights (LED) 200 200 Coffee Machine (Commercial) 1,500 2,000Pro-tip: Always check the compliance plate on your specific tool. Manufacturers vary significantly.
Matching the Generator Type to the Job
Once you have your total wattage, you aren't finished. You need to consider the type of generator. Not all power is created equal.
1. Inverter Generators
If you are running sensitive electronics—laptops, sound systems for an event, or modern power tool chargers—you want an inverter. They provide "clean" power that won't fry delicate circuitry. They are also much quieter and more fuel-efficient, but they usually max out at lower power outputs.
2. Frame-Mounted (Open Frame) Generators
These are your workhorses. If you’re running circular saws, welders, or heavy-duty compressors on a construction site, you want a frame-mounted unit. They are rugged, handle sustained high-wattage draws better, and are designed for the grit of a job site.
Fuel Choice and Daily Run Time Planning
Are you running this thing for an hour or an entire shift? This is a crucial question for the hire yard.
- Petrol: Great for short-term, portable needs. Easy to transport, but if you’re running it for 8–10 hours a day, you’ll be spending a fortune on fuel and spending your afternoon doing "refuel runs." Diesel: If you need reliable power for a full day, get a diesel unit. They are more expensive to hire but much cheaper to run. Plus, they generally have longer run times on a single tank.
Always ask the hire team, "What is the fuel consumption per hour at 75% load?" This will help you plan your logistics.
Noise and Local Considerations
If you’re doing a backyard reno in a dense residential area, do not hire an open-frame industrial generator unless you want the neighbors knocking on your door by 7:30 AM. Local safe generator operation in rain councils have strict noise regulations. Look for "Super Silenced" models if you are working in a residential zone. If you’re on a remote construction site, noise matters less, and you can save money by renting a standard unit.
How to Talk to the Hire Yard (The "Winning" Call)
When you finally call, don't just ask "how much for a generator." Use your list! A good counter hand will be able to help you immediately if you provide the right data. Many yards now use live chat tools—sometimes powered by systems like Chatlio—which allow you to upload your wattage list directly to the hire desk. If you can provide a list, you look like a pro, and we will move your request to the top of the pile.
The Checklist before you dial:
Total Running Watts of all items used simultaneously. The highest Starting Wattage of any single tool on your list. Site location (Residential vs. Industrial). Expected run time (Hours per day). Transport availability (Do you have a ute/trailer to pick it up, or do you need delivery?).If you take the time to figure out your power requirements before you reach out, you’ll find that hire yards will be much more willing to give you a deal. We like customers who make our job easier because it means the equipment comes back in one piece and you don't call us up crying that your project is stalled.
Found this helpful? Leave a comment below! If you have a specific project coming up and aren't sure about your power load, drop your list in the comments and I’ll help you estimate your needs.
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Disclaimer: Always follow manufacturer safety instructions when operating heavy machinery. If you are unsure about electrical safety, consult a licensed electrician before connecting your tools.