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Generators and Storm Prep in NH

Updated 2026-10-10 · 6 min read

Run a portable generator safely, why backfeeding kills, transfer switches and permits in NH, fuel storage, outage reporting, downed lines and storm trees.

Portable generators and carbon monoxide

A portable generator's exhaust is full of carbon monoxide (CO). The U.S. Consumer Product Safety Commission says CO from a gasoline-powered portable generator can kill in minutes, and that nearly 100 people a year in the U.S. die from CO poisoning caused by portable generators (CPSC, February 2026). CPSC's rules:

Run a portable generator outside only, at least 20 feet from the house.
Never run it inside a home, garage, basement, crawlspace, shed or other enclosed space. Opening doors or windows will not provide enough ventilation.
Don't run it on a porch or in a carport. Point the exhaust away from your home and other buildings' entrances.
When buying, look for a model with a CO shut-off safety feature.

CO alarms, refueling and fuel storage

The NH State Fire Marshal gives the same 20-foot distance from doors, windows and other openings, and recommends CO alarms outside each sleeping area and on every level, including the basement. Ready.gov recommends CO detectors with battery backup in central locations on every level. Test alarms monthly. If an alarm sounds or anyone feels dizzy, sick or confused, get everyone outside to fresh air and call 911. Our chimney and wood stove guide covers New Hampshire's CO detector law.

Turn the generator off and let it cool before refueling; CPSC warns never to refuel a running generator, and Ready.gov notes that fuel spilled on hot engine parts can ignite. For gas cans, CPSC's fuel container guidance says to store them only in cool, well-ventilated areas, never inside a house or basement or near ignition sources such as pilot lights, stoves and heaters, and to keep them out of children's reach.

Never backfeed your house

Connecting a generator to house wiring without the right equipment can send power backward out of your house and onto utility lines. That's called backfeeding. NHEC explains that power from an improperly connected generator can flow onto the grid, where it is stepped up to very high voltage and endangers line workers. Eversource warns it can also hurt neighbors. ReadyNH tells residents not to connect a portable generator to the home's electrical system.

If you want a generator to power house circuits, the safe ways are a transfer switch or an interlock:

NHEC says the safest way to connect a generator is to have a licensed electrical contractor install a transfer switch.
Eversource describes two choices, an interlock or a transfer switch, and says both are better and safer than extension cords. An interlock requires you to shut off the main breaker before connecting the generator. A transfer switch does that work for you.
Unitil says a double-throw transfer switch is required when connecting a generator to permanent wiring, and recommends a licensed electrician and a local wiring inspection.

Licensing and permits for generator hookups

In New Hampshire, electrical installations done for pay must be made by a licensed electrician (RSA 319-C:1). The law has a narrow exception for a homeowner working on the single-family home they own and live in (RSA 319-C:15), but a transfer switch or interlock is serious work, and the utilities above recommend licensed or professional installation. OPLC licenses electricians through its Electricians' Board, and its website has a license lookup. See our guide to hiring an electrician.

A permanently installed standby generator that runs on propane or natural gas involves both electrical work and gas work. Propane or natural gas piping is fuel gas fitting, which New Hampshire licenses through the Mechanical Licensing Board. State law exempts an owner doing gas work in the single-family home they own and live in, but even then the work must meet code and any permit and inspection requirements (RSA 153:36).

Permits are set locally. Before work starts, ask your town's building department and fire department which permits apply, such as an electrical permit and a gas permit, and what they require for placement and clearances. Our building permit guide has more.

Get ready before storm season

ReadyNH, a campaign created by NH Homeland Security and Emergency Management, recommends a kit with at least a 3-day supply of food, water and medicine, checked regularly because items expire. It also suggests a family emergency plan covering how you'll reach each other and where you'll go. Other tips from ReadyNH's power outage page:

Learn how to work the manual release on an electric garage door opener.
Keep your car's fuel tank at least half full, since gas pumps need electricity.
If you use medication that needs refrigeration, ask your doctor or pharmacist how long it keeps.
If someone in your home depends on electric medical equipment, NHEC advises having a battery backup or other arrangements (NHEC).
Have your heating system checked by a professional each year, as ReadyNH's winter storm page recommends.

When the power goes out

Report the outage to your utility. Eversource takes reports online with your phone number or account. NHEC members can report through SmartHub, by text or by phone. Unitil takes reports online. Check your utility's site for current phone numbers.

ReadyNH's outage advice: keep the refrigerator and freezer closed (an unopened fridge stays cold about 4 hours and a full freezer about 48 hours), use flashlights rather than candles, turn off equipment you were using when the power went out, never use a gas oven for heat, and check on your neighbors.

Downed lines and storm-damaged trees

Treat every downed wire as live. From ReadyNH, Eversource and NHEC:

Don't touch power lines, and keep family and pets away. Call 911 to report downed lines.
Stay clear of fallen limbs and wires and anything they are touching, and don't drive over a downed line (Eversource).
If a line falls on your car, stay inside until emergency crews arrive.
If the meter or service line on your house is damaged, contact your utility. NHEC notes that damaged meter housing may need repair by a licensed electrician (NHEC).

Trees near your service line

Utilities trim along their own lines, but the wire from the pole to your house is often on you. Eversource says it may remove branches rubbing your service wires at no charge, and if you hire your own tree company it will temporarily take down the pole-to-house line so the work can be done safely (Eversource NH tree trimming FAQ). NHEC tells members to stay at least 10 feet from energized lines, never to cut trees or branches touching the lines, and to call before working near a service line so power can be shut off (a fee applies).

Fall is a good time to have a tree service look at dead or leaning trees near the house, and to have a roofer check the roof before snow. After a storm, an electrician can repair damage to your home's electrical equipment.

This guide is general information. Confirm permit and licensing requirements with your town and OPLC, and follow your utility's current safety instructions.