A commercial generator is quoted in kilowatts, and the size you need is set by the largest motor starting on the site rather than by the sum of the nameplates. Get that wrong upward and you pay for a machine that idles wet; get it wrong downward and the set stalls every time a compressor kicks in. Rental fleets run from 20 kW towables at roughly $150 to $250 a day up to 500 kW skid units.
Size for the starting load, not the running load
Motors draw several times their running current for the first second or two, so a site whose steady demand is 15 kW may need a 30 kW set to start a single large compressor without dipping the voltage. List every motor, note the biggest one, and give the yard both figures. A good counter will size from that conversation rather than from a guess at square footage.
The classes yards actually stock
Below about 25 kW the machines are towable, single-phase or switchable, and plug into standard site distribution. From 30 to 150 kW they are trailer-mounted diesel sets with three-phase output and a camlock panel. Above that they are skid units delivered by truck, which need a crane or a forklift at both ends and a level pad prepared before delivery.
Fuel is the line that moves
Most rental sets carry a belly tank sized for roughly 24 hours at half load, and consumption climbs steeply as load rises. A 60 kW unit working hard can drink 4 to 5 gallons an hour, so a week of continuous running is a fuel bill larger than the rent. Agree whether the yard refuels on a schedule or you do, and at whose price.
Connection is the part to plan first
A rental set arrives with an output panel, not with cable. Feeder cable, distribution boxes, ground rods and a transfer switch are separate hires, and connecting a generator to a building's wiring is licensed electrical work in every state. Book the electrician before the machine, because a set sitting idle on the pad still bills its day rate.
Questions people ask about commercial generator rental near me
What size generator runs a small commercial site?
A single trade with hand tools and a few lights is usually fine on 6 to 12 kW. Once welders, compressors or temporary HVAC are involved, 30 to 60 kW is the common answer. The starting current of the largest motor sets the floor either way.
Is a rental generator delivered with fuel?
Normally it arrives with a full tank and is expected back full, or is refuelled by the yard at its posted rate. On long hires many yards will add a scheduled fuel delivery, which is billed separately from the rental line.
Can I connect a rental generator to my building myself?
No. Tying temporary power into a building's distribution is licensed work and needs a transfer arrangement so the set can never backfeed the utility. Yards will hire you the machine and the cable, but not the sign-off.