Standby vs portable generators for home backup

Affiliate disclosure: some store links on HoldBackup are affiliate links. If you buy through one, HoldBackup may earn a commission at no extra cost to you. As an Amazon Associate I earn from qualifying purchases. How HoldBackup makes money

Standby generators

A standby generator sits outside on a pad, usually runs on natural gas or propane, and connects to your panel through an automatic transfer switch. When the grid drops, it starts on its own and takes over the circuits it was sized for. When the grid returns, it hands back and shuts down. It needs a licensed electrician (and often a gas fitter for the fuel line), usually a permit, and routine maintenance. It suits homes where outages last days, or where power has to come back on its own while nobody is home.

Portable generators

A portable generator is wheeled outside, fueled (often gasoline, some models also propane), and started by hand or with a button. It can run a few appliances on heavy-duty, outdoor-rated extension cords sized for the load, or feed chosen circuits through a generator inlet and a transfer switch or interlock kit that an electrician installs. Inverter models are quieter and make steadier power for electronics.

The safety rules that never change

• Never run a generator inside a home, garage, basement, crawlspace, or shed, even with the doors and windows open, and don't run a portable one on a porch or in a carport. Its exhaust carries carbon monoxide, which can kill in minutes. The U.S. Consumer Product Safety Commission says to run a portable generator outside, at least 20 feet from the house, with the exhaust pointed away from the home and any building people can enter.
• Never plug a generator into a wall outlet to feed the house. That backfeed can electrocute utility workers and damage equipment. Use a transfer switch or interlock installed by an electrician.
• Turn a portable generator off and let it cool before refueling.
• Look for a portable generator with a carbon monoxide shut-off feature.
• Put carbon monoxide alarms that run on batteries, or have battery backup, outside sleeping areas and on every level of the home.

Which one fits

Start from the circuits you need on, as in the battery backup, UPS, and generator guide. If outages where you live are short and rare, a portable power station or a portable generator with an inlet usually covers them. If they run for days, or power has to come back while you are away, a standby unit is worth pricing with a licensed installer.

Connecting a portable generator to the panel

Feeding house circuits from a portable generator takes transfer equipment installed by a licensed electrician, and the plugs have to match. The Reliance Controls 30310A is an indoor 30-amp, 10-circuit manual transfer switch. Reliance's spec sheet for the 30310A lists a NEMA L14-30 inlet (30 A at 250 V), a 7,500 W maximum generator input, and 240 V circuits through paired positions. The switch mounts inside, next to the panel; the electrician moves the circuits you choose onto it. The generator still runs outside. The Champion on this page has no L14-30 outlet, so it does not plug into this switch; the plug section below explains.

The generator cord plugs in outside, at an inlet box the electrician mounts on the exterior wall and wires to the switch, so no cord runs through a door or window. The Reliance PB30 is an inlet that matches this switch: a 30-amp, 120/240 V box with an L14-30 inlet, rated for outdoor use.

Read the plugs before you buy any of this. L14-30 carries four wires: two hot legs, a neutral, and a ground, which is how the switch gets 120 V and 240 V. TT-30R, the RV outlet on the Champion above, carries three wires, one hot leg, a neutral, and a ground, so it is 120 V only, and Champion rates it at 25 A. The two do not fit each other. The proper match for this switch and inlet is a generator with an L14-30 outlet. Adapters that bridge a TT-30 plug to an L14-30 inlet are sold; HoldBackup does not link one, and you should not buy one on your own. Whether your switch may be fed that way, and how the generator's neutral has to be set for it, is for the electrician who installs the switch to decide. Even then only the 120 V circuits on the switch get power: its 240 V positions stay dead, so a 240 V well pump, a central air conditioner, or an electric dryer stays off. The same plug question applies to an interlock install.

HoldBackup does not link an interlock kit. Interlock kits are made for one panel brand and model, and a kit that fits your neighbor's panel may not fit yours or pass your inspection. If you go that route, your electrician picks the kit listed for your exact panel.

Best inverter generator for a home outage compares units from the makers' numbers. Every guide in this class is in Portable generators.

Questions