The Real Generator Buyer's Checklist: What I Learned After Processing 60+ Orders

If you're tasked with buying a generator—whether it's a steam turbine for a power plant or a quiet unit for a mobile home—you probably have a list of specs in front of you. But the spec sheet won't tell you which vendors are reliable, what hidden costs to expect, or how to avoid the kind of mistake that gets you a call from Finance on a Friday afternoon.

After managing roughly $250,000 in annual equipment orders across 8 vendors—including generators, transfer switches, and welding gear—here's the checklist I wish I'd had when I started. Five steps. Follow them in order.

Step 1: List Your Load Requirements (and Don't Guess)

This sounds obvious, but I've seen purchase orders for generators that were sized by “feeling.” A facility manager once told me, “We run 50 computers, a few lights, and an AC unit—so 30 kW should be fine.” That order ended up being undersized by 40%.

You need to calculate the starting load, not just the running load. Motors—like those in compressors, pumps, or welders—draw 3-7x their running current on startup. Use a power meter or get quotes from an electrical contractor. For a steam turbine in power generation, you'll need TURBINE-specific load data: steam flow, inlet pressure, extraction points. For a diesel welder, factor in the welding duty cycle.

What I mean is that the cheapest 20 kW generator isn't a deal if it can't start your 5 hp compressor. The surge rating matters more than the continuous rating for most sites.

The question isn't “Can we fit it?” It's “Can it start everything at once?”

Step 2: Set a Budget (Plus 30% for Hidden Costs)

Budgeting for a generator is like budgeting for a car—you think you know the price, then you add installation, wiring, fuel lines, permits, and delivery. I've seen a $15,000 generator turn into a $22,000 project.

Here are the cost buckets you need to account for:

• Generator itself: Get quotes for the base unit. Quiet commercial generators run 10-30% more than open-frame models of the same capacity.
• Transfer switch: For a gas generator connecting to a home panel, a 200-amp transfer switch runs $400-$1,200. For industrial systems, expect $2,000-$8,000.
• Installation: Concrete pad, wiring, connections—typically 15-25% of the generator cost.
• Fuel system: Natural gas line work, propane tank rental, or diesel tank installation. For mobile homes, propane is often the simplest option.
• Permitting & inspection: Varies by city. Budget $500-$2,000.
• Delivery: Crane or flatbed for larger units. I once paid $800 to get a 500 kW generator onto a rooftop—no elevator.

I wish I had tracked the total project cost more carefully from the start. What I can say anecdotally is that the generator itself is usually only 50-60% of the final bill.

Step 3: Verify Fuel Availability (Critical for Diesel and Gas Models)

This is the step most buyers skip. “We'll use diesel—easy.” But diesel generators require a fuel supply that doesn't degrade. If you're buying an industrial generator for a remote site, you need to ensure diesel delivery is reliable. I've seen sites run out of fuel because the local supplier had a minimum order of 500 gallons—and the tank only holds 200. (Should mention: the vendor changed its policy without notice.)

For natural gas or propane models, check with the utility company for line capacity. A 50 kW generator running at full load consumes roughly 600 cubic feet per hour of natural gas. Your line might not handle that plus your building's other gas appliances. For mobile homes, propane is often the answer—but check the tank size. A 100-gallon tank running a 10 kW generator at half load will last about 3 days before needing a refill.

To be fair, some vendors will tell you this upfront. But not all—especially if they're trying to close the sale.

Step 4: Check the Supplier's Class Expertise (Not All Generator Suppliers Are Equal)

Here's something vendors won't tell you: a supplier who sells portable generators for construction sites might not be the best choice for a 5 MW steam turbine for power generation—or vice versa. I once requested a quote for a quiet commercial generator from a supplier who specialized in industrial diesel sets. The quote was competitive, but the unit was loud—not suitable for a residential neighborhood. (I assumed “commercial” was “quiet.” It wasn't.)

What most people don't realize is that the transfer switch for a gas generator requires different wiring than a diesel setup. The supplier should know the building code requirements for your area. If they can't answer basic questions about load shedding or automatic transfer switching, walk away.

Oh, and check if they offer a wiring diagram—not just a generic schematic, but a diagram specific to your model and transfer switch. That alone can save you hours of electrician labor.

I don't have hard data on industry-wide supplier quality rates, but based on our 5 years of generator orders, my sense is that about 20% of suppliers don't fully understand the product they're selling—especially when it comes to quiet commercial units or specialized applications like mobile homes.

Step 5: Inspect the Unit (and Negotiate Delivery Terms)

Don't just order a generator and hope it shows up. If possible, inspect a unit at the supplier's yard—or at least ask for recent photos of a similar model being built or tested. For industrial generators for sale, ask for a load bank test report. This shows the unit actually produces its rated power.

A friend of mine—an electrical contractor—ordered a 250 kW diesel generator for a data center. The supplier sent a photo of a similar unit. When it arrived, the control panel was dented, the cooling fan didn't engage, and the voltage regulator was from a different brand. The lesson: ask for the serial number of the specific unit you're buying.

For mobile home installations, you might not be able to inspect before delivery. In that case, negotiate a conditional acceptance period—say, 7 days to test the unit after installation. If it fails, the supplier covers return shipping.

The question isn't “Can you deliver?” It's “What happens if the unit arrives damaged or doesn't work?”

Common Mistakes & Things to Watch For

• Not factoring in voltage requirements: In the US, residential generators are usually 120/240V, single-phase. For industrial sites, you might need 277/480V three-phase. A diesel welder may require 240V single-phase with a dedicated neutral for the welding circuit. Get this wrong, and the generator will need a transformer—adding $1,500-$5,000.
• Ignoring noise regulations: Some cities have strict noise limits for generators, especially at night. “Quiet” is relative. Check the decibel rating (dB) at 23 feet. For residential areas, you want something in the 60-65 dB range—that's a quiet commercial generator. Anything above 70 dB will get complaints.
• Forgetting about the warranty registration: Many manufacturers require the unit to be installed by a certified electrician for the warranty to apply. If you install it yourself, the warranty might be void. Get it in writing before you sign.
• Underestimating fuel storage requirements: For diesel generators, the tank should be sized for at least 72 hours of continuous run time at full load. A 100 kW generator consumes roughly 7-8 gallons per hour. That means a 500-gallon tank is the minimum for a 3-day run. For less critical sites, 24 hours might be enough—but check your needs with the supplier.

This checklist isn't exhaustive—every site has its quirks. But if you follow these five steps, you'll avoid the biggest headaches I've seen over the last 5 years of buying generators and related equipment. (Should mention: prices vary by region and market conditions. Verify current fuel costs and generator availability with local suppliers before committing to a purchase.)