Perkins Generator FAQ: Sizing, Service & Installation Insights from an Admin Buyer
I’m an office administrator for a mid-sized company. I manage all our equipment and service ordering—roughly $200k annually across 6 or 7 vendors. I report to both operations and finance. When I took over purchasing in 2020, I didn't know a kVA from a kW. I’ve since learned a ton, often the hard way. This FAQ covers the questions I see most often about Perkins generators, from sizing to installation.
How do I choose between a 35 kW and a 700 kVA Perkins generator?
This is the first question everyone asks, and it's a good one. A 35 kW generator is a solid choice for a small factory line, a large retail store, or a medium-sized office's essential systems. A 700 kVA unit (which is about 560 kW) is a whole different beast—it's for powering a whole hospital, a data center, or a manufacturing plant. I assumed 'just scale up' when I was looking at specs for a new facility expansion. Didn't verify. Turned out the electrical load calculation is way more nuanced than that.
You really need a load study. Get an electrician to do a 7-day audit of your highest demand. It's a few hundred bucks and can save you from overspending on a monster unit or, worse, buying one that can't handle a surge. If I remember correctly, the rule of thumb is to size for 80% of your peak load to allow headroom for starting electric motors.
Is a Perkins generator better than a Kohler marine generator?
Comparing a Perkins to a Kohler marine generator is a bit like asking if a Ford F-150 is better than a Yamaha outboard motor. They're built for different things. Perkins engines are legendary for their durability in industrial and standby applications—they're workhorses. Kohler makes excellent marine generators that are designed to handle the salt, moisture, and vibration of a boat.
For land-based, general commercial or industrial use, a Perkins is a fantastic choice. For a yacht or a commercial vessel, you'd want a dedicated marine unit. Bottom line: choose the tool for the job. The brand heritage of Perkins is about overland reliability, not necessarily seafaring. (Should mention: we've used both; Perkins for our main plant, and the facilities manager for a marina I know swears by Kohler for their boats.)
How often do I need to do a Bobcat fuel pump replacement on a generator?
This is one of those maintenance details that can trip you up. 'Bobcat' usually refers to a specific type of fuel pump or priming pump used on some diesel engines, including some Perkins models. A fuel pump isn't a routine replacement item like an oil filter. You replace it when it fails or shows signs of wear.
The most common cause of failure is contaminated fuel or running the tank dry, which sucks debris into the pump. We didn't have a formal fuel quality check process. Cost us when two pumps failed in a year because of bad diesel. The third time we had a pump issue, I finally created a fuel testing and filtration checklist. Should have done it after the first time. A good service contract will include regular fuel testing and filter changes, which protects the pump.
"The value of a guaranteed maintenance schedule isn't the labor—it's the certainty that your backup power will actually work when the grid goes down."
Can I install a generator transfer switch myself?
I get this question all the time from internal teams trying to save money. The short answer is: legally and safely, probably not. How to install generator transfer switch is a question that should be answered by a licensed electrician, not a DIY article.
In most jurisdictions, a transfer switch is part of the building's electrical system. Installing it wrong can backfeed power into the grid, which is dangerous for utility workers and can kill someone. It can also fry your generator or your building's electronics. The cost of hiring a professional is a no-brainer when you compare it to the risk of a fire or an outage during a critical moment. We paid $400 extra for a rush install by a certified electrician in March 2024. The alternative was missing a critical production deadline.
Even after choosing to pay for the pro, I kept second-guessing. What if I could have figured it out? The two weeks until the final inspection were stressful. Didn't relax until the electrician signed off and the system passed its load bank test.
What's a good price for a 35 kW or a 700 kVA Perkins generator?
Pricing is all over the map and changes with the market. For a ballpark, a 35 kW diesel generator (not just the engine, but the whole package with enclosure and controller) might be in the $15k-$25k range. A 700 kVA unit can easily be $100k-$200k+ depending on the extras (sound attenuation, larger fuel tank, remote monitoring). These are rough numbers based on quotes we got in late 2024; verify current pricing.
The worst mistake is buying on price alone. A cheaper generator might have a different engine, a lesser controller, or a weaker alternator. The total cost of ownership includes installation, maintenance, and potential downtime. A cheap unit that fails during a power outage is the most expensive generator you could ever buy. I want to say we saw a 40% price variation between a 'good deal' and a reputable dealer for the same spec, but don't quote me on that exact number.
How do I find a reliable Perkins generator service dealer?
This is even more important than the initial purchase. A great generator that no one knows how to fix is a paperweight. Look for a dealer that is an official Perkins distributor or has certified Perkins technicians. Ask them how quickly they can get parts—a generator is useless if you have to wait 3 weeks for a fuel pump replacement.
Check their response time history. The vendor who couldn't provide proper invoicing for a simple repair cost us $2,400 in administrative overhead and lost productivity. An unreliable service partner made me look bad to my VP when a routine service dragged on for a week. I now use a checklist that includes: parts availability, technician certification, and a clear SLA on response time. It's super important.
