The call came in at 5:48 a.m. on a Thursday in late February 2024. I was already awake. New England ice storms have a way of keeping emergency generator people like me on edge. They also have a way of not calling ahead.
The voice on the other end belonged to a shop owner in East Haddam, Connecticut. He runs a custom millwork shop out of an old building near the river. The power had gone down around 2 a.m., when a tree limb hit the line down the road. His antique Kohler generator had started, run for about ten seconds, and shut itself off. The shop was at 41 degrees and falling. A $40,000 cabinet order was in the middle of a finishing process that does not like cold air.
I told him I would be there by 6:45. I made it with about three minutes to spare.
My First Diagnosis Was Wrong
On the drive over, I made the same mistake I see a lot of people make with older generators: I blamed the fuel. The owner had already told me it had not been serviced since the previous winter. That sentence is practically the opening line of half my emergency calls.
But the machine didn't sound fuel-starved. It cranked, caught, ran for several seconds, and then stopped as if someone had hit the kill switch. A fuel problem stumbles and coughs before it gives up. This was an abrupt shutdown, which meant the trouble was probably electrical.
So there I was, standing in a cold workshop in East Haddam, holding a carburetor kit I didn't need, staring into the control box of the antique Kohler generator. A mouse had built a nest in there, using fiberglass insulation and what looked like an old gas receipt. It had chewed through the insulation on a wire that runs to the low-oil shutdown switch. The bare wire was touching the engine block. Oil pressure was fine. The engine was fine. But every time the generator vibrated, that chafed wire told the safety switch to kill the engine.
The safety system was doing exactly what it was designed to do. The generator wasn't dying on its own. It was being told to die.
Fixing it properly would take me about an hour, and the shop didn't have an hour to wait at 39 degrees. That's when we pulled out Plan B.
Plan B: A Milwaukee Portable Generator
The shop also owned a Milwaukee portable generator, a jobsite unit the owner used for trim work. It was not a replacement for the permanently installed Kohler, but it could carry the furnace circulator, a couple of lighting circuits, and some outlets.
The owner pulled out a 30-amp extension cord and pointed toward the dryer outlet. “Can't we just backfeed through this?” he asked.
That question is the reason I keep a standard explanation ready. Backfeeding through a dryer outlet energizes the entire panel, including the service conductors upstream. A utility worker down the road can be killed by power that no one knows is live. There is no version of "just this once" that makes it safe.
Backfeeding was also unnecessary. The portable generator had enough fuel for six or seven hours, which was exactly enough time to keep the heat on while I made the permanent repair. The only thing missing was a safe connection.
Generator Interlock vs Transfer Switch: Decide Before the Storm
The two safe ways to connect a portable generator to a building are a generator interlock and a transfer switch.
A transfer switch is the more complete solution. It physically moves selected circuits from utility power to generator power, so the two sources can never meet. It costs more and usually needs an electrician, but it leaves very little room for operator error.
An interlock kit is the lower-cost option. A metal plate mounts on the panel and prevents the main breaker and the generator feed breaker from being closed at the same time. When installed with listed equipment by a qualified electrician, it's an accepted solution in most jurisdictions where I work.
For this shop, an interlock was the right practical choice. The bigger point is timing. Choosing between a generator interlock vs transfer switch should happen when the lights are on and the phone is not ringing with outage complaints.
The Stihl MS250 Spark Plug Almost Stalled the Whole Plan
Before we could roll the Milwaukee portable generator into position behind the shop, we hit another obstacle. A birch limb had come down overnight and blocked the shed door. The owner grabbed a chainsaw, a Stihl MS250, and pulled the cord. Nothing. He pulled again. The saw caught once, ran rough for two seconds, and died.
I didn't need to ask how old the spark plug was. The saw's symptoms told the story.
I pulled the plug and found it fouled, with a black crust on the electrode. A Stihl MS250 spark plug is a small part and a five-minute replacement on a workbench. When a tree branch is blocking the only path to your backup generator, it becomes the most important part on the property. I cleaned it, set the gap, and put it back in. The saw fired on the second pull.
The repair was free. The maintenance that would have prevented it would have cost about six dollars and ten minutes.
Bringing the Antique Kohler Generator Back to Life
With the Milwaukee portable running through the interlock, the building started to warm up. I finally had the time to fix the Kohler properly.
I removed the damaged wire from the control panel, soldered a splice, sealed it with shrink tube, and routed the harness away from the vibrating engine block. Then I did the annual service the owner had postponed: oil change, new air filter, cleaned ignition points, and a full inspection of the control wiring. The carburetor was fine. I never opened the kit I had brought.
There is something deeply satisfying about watching an antique Kohler generator settle into a steady run under load. The old cast-iron engine has a rhythm you don't find in modern appliances. I loaded the set and let it run for 45 minutes. It didn't miss a beat.
The Real Cost Was Not the Repair Bill
The owner asked what he owed me. The number was fair, and he didn't flinch. But the real cost of that morning was the lost production time. His crew lost most of a day, the finishing schedule slipped, and the $40,000 cabinet order barely stayed on track.
I don't have hard data on what percentage of generator failures start with rodents, chafed wires, and fouled spark plugs. After eight years of emergency calls, my anecdotal answer is: more than anyone wants to admit.
If that shop owner had searched for Kohler generator dealers in East Haddam back in the fall, a preventive maintenance visit would have caught the mouse damage before it mattered. The saw would have received a new spark plug. The interlock decision would have been made calmly. The emergency would have been a non-event.
Five minutes of verification beats five days of correction. Every time.
That is the message I bring to every commercial customer now. Exercise your generator under load. Check the wiring. Decide on a generator interlock vs transfer switch while the lights are still on. Replace the Stihl MS250 spark plug while the saw still starts. None of those tasks are expensive.
All of them cost less than that Thursday morning in East Haddam.
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