Unlike a lot of equipment purchased for the jobsite, small, portable generators (the size you can throw in the back of your truck) can be picked up on a quick weekend trip to Home Depot. And certainly, some of those can meet your needs, but choosing a low-end product, or one that doesn’t have a jobsite in mind, will cost more in the long run and possibly compromise some of your tools along the way. Right off the bat, before digging into the specs, Occupational Safety and Health Administration (OSHA) compliance is a requirement for generators used on jobsites, which means full-panel, neutral-bonded ground fault circuit interruption (GFCI) protection is a must. If you don’t see that, then you must keep moving.
The primary difference between construction-grade portable generators and those intended for homeowner use, according to Matthew Moose, product manager, Generac, is durability, which makes sense. Generators on construction sites run longer and get knocked around more, so they have to be tough in terms of design as well as manufacturing.
“Traditional portable generators designed for residential use will likely suffer premature engine failure — even with regular maintenance,” he says. “That assumes it survives being knocked around by lift trucks or just hasty transport. So, the construction-grade generators are the best type of generator suited for dusty, hot and busy jobsites. The engines are more robust than a residential or inverter portable generator, and they are better protected from the outdoor elements with covered outlets and stronger frames.”
Sizing the right generator for the job can get tricky. Buying too large of a generator for a job will just mean more noise and more fuel, which is why a common solution today is one generator per worker to run their tools and charge batteries. But in that smallest range of portable generators (2,000 to 3,000 W), engine size is of huge importance. When scouting potential handheld generators, take a look at the rated wattage and compare it to engine size. If the engine is built to just match that rated performance, there is a greater likelihood of maxing its performance limitations.
For example, Tom Pernice at Honda Power Equipment, says Honda specifically overbuilds its 2,000-W generators. This way, the generator remains a lightweight, nimble solution for the jobsite but provides a 20 percent larger displacement engine that’s capable of 20 percent more power. And hey, if you need to size up, you can link two together in parallel and double the output to 4,000 W and remain under 100 lbs.
“We will rate things at the lowest end of its performance so that you can expect better real world performance than what it’s labeled for,” he says.
Engines for generators on the jobsite also need to be durable to handle more constant, lengthy operating times. Honda equips its generators with Oil Alert, which protects the engine by shutting it down if the oil pressure level dips too low. Pressurized lubrication is a big help here, too.
“Many residential-type portables have what’s called ‘splash lubrication,’ in which oil in the crankcase is simply agitated by the action of the engine and splashed on moving components,” Moose says. The G-Force engine from Generac provides full-pressure lubrication to ensure critical engine components stay lubricated.
Wattage doesn’t tell the whole electronic operating story. A generator with a low-end brushless capacitor design will sure provide the wattage it says it will and will power the tools that need it, but without quality voltage regulation, the performance will be erratic — from over to under power — and start to destroy tools over time. Buying a generator with automatic voltage regulation (AVR) is especially important today, when many professional-grade tools have sensitive electronics that require clean, stable power to operate.
“The trick is maintaining that 3,600 rpm through changing loads. That’s what the AVR is doing,” Pernice says. “It gives a good sine wave and does not damage tools.” Honda has started to make AVR control an electronic function instead of a mechanical function, borrowing functionality from its inverter technology. “Digital just improves response time to changing loads. Electronic control can sense the rush of the large load startup and will boost the engine performance so it won’t drop voltage when that large load hits. … Our inverters respond to load and are not dependent on rpm.”
Honda’s 5,000-W generator, for example, will put out 7,000 W for up to 10 seconds, which is an advantage for large load applications. This way, you can buy a 5,000-W generator instead of a 6,500-W if you were only upscaling to account for that short interval during startup.
A certain amount of physical abuse needs to be factored into any equipment purchase, and small portable generators have a warning right in their name — portable. These things are on the move. They will be dropped, bumped, tossed into trucks, etc., and they need to be able to handle it all. Many lightweight inverter generators out there are ideal for camping and tailgating environments, but on the jobsite it’s only a matter of time before their plastic cases get cracked.
“Construction-grade frames are made with stronger materials and more of them — protecting more parts of the generator than a residential-grade frame,” Moose says. “On most residential portables, the cradle is less robust and is only intended to hold — not protect — the unit’s components.”
But ancillary physical features should be considered too — stuff a homeowner or camper doesn’t ever need — like a steel lifting pocket on the top of the generator, so that a forklift or telehandler can easily transport the generator long distances on the jobsite. The new XC Series from Generac, for example, has the X-FRAME — a fully wrapped, heavy-duty, 12-gauge steel tube frame that protects the engine, alternator and fuel tank from damage, as well as an impact-resistant fuel tank.
As always, maintenance needs of the equipment play a big part in their overall value. Moose recommends a generator that makes it possible to access all routine maintenance items, like the air filter and spark plug, without removing the fuel tank or side panels.