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Practical advice from a licensed Mat-Su Valley electrician.
If you’re thinking about a backup generator, the first real question isn’t which brand to buy, it’s what size you actually need. Get it right and your home rides out a winter outage without you thinking twice. Get it wrong and you either pay for far more generator than you’ll ever use, or you find out at 20 below that the unit can’t carry your well pump and your furnace at the same time. Here’s how we size a standby generator for a Mat-Su Valley home, in plain terms.
Before we talk kilowatts, we talk priorities. There are really two ways to approach backup power:
Neither answer is wrong. It comes down to your home, your budget, and how you want to live through an outage that might last a few hours or a few days.
Sizing here isn’t the same as sizing a generator in a mild climate. In the Valley, a handful of loads carry real weight:
The single most common sizing mistake we see is adding up the running watts on the nameplates and calling it a day. Motors, and your well pump and furnace blower are motors, draw a big spike of power at the instant they start, well above what they use once they’re running. A generator has to have enough headroom to swallow those surges without stumbling, especially when two motors happen to kick on at once. This is exactly why a real load calculation beats a rule of thumb.
As an Authorized Cummins dealer, we do an in-home load calculation before we ever quote a unit. That means we walk your home, look at your actual electrical panel, note your heat source, your well pump, and your major appliances, and factor in both running and starting loads. From there we match you to the right Cummins Quiet Connect unit, which range from 13kW and 17kW for essential-circuit setups up through 20kW and larger for whole-home coverage, and up to 100kW for commercial jobs. No guesswork, and no oversized quote just to pad the ticket.
If you want a number before we ever come out, our generator sizing calculator walks you through the same running-watts-plus-surge method and recommends a Cummins model in about a minute.
Every home is different, but to give you a general sense before we come out:
Treat these as a conversation starter, not a final answer. The only number that matters is the one that comes out of measuring your specific home.
Most sizing advice warns you about buying too big, and that is real, an oversized unit costs more and burns more fuel. The failure that actually hurts, though, is buying too small. A generator run at the ragged edge of its capacity does not just trip and stop. It can sag the voltage under load, and those brown-outs are hard on exactly the things you bought it to protect: furnace control boards, well pump motors, refrigerators, and anything with a circuit board in it.
The stakes go up if there is medical equipment in the house or you work from home and need power that is actually stable, not merely present. Size it to carry your real load with headroom to spare and the generator becomes something you stop thinking about, which is the whole point.
A generator is only half the system. The transfer switch is what actually connects that generator to your home safely and, in the case of an automatic switch, what starts the unit and restores power on its own when the grid drops. When we size a generator, we size the transfer switch and the connected loads right along with it. You can read more about your options on our transfer switch installation page, or see the full picture on our home backup generator installation page.
For an average Mat-Su Valley home, whole-home backup often lands in the 20kW range, but electric heat, a big shop, or higher square footage can push it higher. The honest answer is that it depends on your actual loads, which is why we do a free in-home load calculation before recommending a unit.
Yes, and for most Valley homes keeping the well pump running is one of the main reasons to install one. The key is making sure the generator has enough headroom for the pump’s starting surge, which we account for when we size the system.
An oversized generator costs more up front, burns more fuel, and can actually run less efficiently under a light load. Bigger isn’t automatically better. The goal is the right size for your home, not the biggest one on the lot.
The best way to know what you need is to have a licensed electrician measure it. Call AK Sparky’s Electric at 907-671-9288 or schedule online, and we’ll do an in-home load calculation and walk you through your options, with upfront pricing and no pressure.
Straight answers, upfront pricing, and a crew that shows up on time.
Ready when you are
Licensed, bonded & insured electricians serving Wasilla, Palmer, and the greater Mat-Su Valley.
