verifiedbackuppowerdata
Boundaries

The four things that actually hurt people

Backup power goes wrong in a small number of predictable ways. None of them are about choosing the wrong brand.

Carbon monoxide

Never indoors. Never in a garage. Never near a window.

A portable generator burning fuel produces carbon monoxide: no color, no smell, and lethal at concentrations you cannot detect. An open garage door does not make a garage safe, and neither does a covered porch or a crawlspace.

Run a fuel generator outdoors, well away from doors, windows and vents, with the exhaust pointed away from the building. Fit working CO alarms inside. If anyone feels dizzy, weak or nauseated during an outage, get into fresh air first and ask questions afterwards.

This is the reason our planner has an indoor-only option, and the reason that ticking it shows you the generators it excluded instead of quietly hiding them. A battery power station produces no combustion gases and is the option that can run indoors.

Backfeeding

Never run a cord from a generator into a wall outlet.

Feeding power backwards into your house wiring pushes voltage back onto the utility line, where it can kill the line workers restoring your power. It also bypasses every protective device in your panel.

How backfeeding sends power out to the streetA generator connected by a cord into a wall outlet pushes electricity backward through the house wiring and out along the utility line to a pole, where a line worker is working. your house generator cord into a wall outlet line worker power flows back out to the street
Never run a cord from a generator into a wall outlet. Power flows backward out of your house and onto the utility line, where it can kill the crew restoring your power. The only safe way to power circuits is a transfer switch or inlet fitted by a licensed electrician.

If you want to power circuits rather than appliances, that is a transfer switch or a generator inlet, installed by a licensed electrician and inspected under your local code. There is no informal version of this job, and we will not publish one.

Starting watts

Anything with a motor or compressor — a fridge, a sump pump, a well pump, an air conditioner — draws several times its running wattage for a fraction of a second when it starts. A unit sized on running watts alone will trip the moment the compressor kicks in, usually in the middle of the night.

Startup surge compared with running wattsA chart of power over time. The line sits at zero while the fridge is off, jumps briefly to about 2,900 watts when the compressor starts, then settles at about 700 watts while it runs. watts time → 700W running 2,900W startup spike under a second off
A refrigerator draws about 700W while running, but jumps to roughly 2,900W for under a second when the compressor kicks in. That spike is what shuts down an undersized power station — not the running watts.

Every load page here shows starting watts alongside running watts, and the planner adds the largest single startup surge on top of your running total before it judges anything as a fit.

Medical equipment

We do not certify anything for medical use.

If losing power to a device is a health risk, the answer is not a wattage calculation. Talk to your equipment supplier about a manufacturer-approved battery for your specific machine, and register with your utility for medical-priority restoration before you need it.

Our CPAP figures assume the humidifier and heated tubing are off, because that is how most people run on battery. With heat on, consumption can multiply several times over.

What needs a professional, every time

  • Anything connected to your breaker panel or house wiring
  • Transfer switches, generator inlets and interlock kits
  • Standing generators and fixed battery systems
  • Gas connections of any kind
  • Anything your local authority requires a permit for — which is most of the above