Generator installation: what to know

What the job involves, what changes the price, and what to ask a pro.

What generator installation is

Generator installation sets a standby or portable-connection generator to supply power to the home during an outage. The electrician mounts the unit on a pad, runs the fuel line, installs a transfer switch or inlet, and performs a safety test. A correct installation keeps generator power out of the utility line, which protects utility workers and the home's wiring.

Signs you need it

  • Outages last long enough to spoil food, lose heat, or stop medical or home equipment
  • You rely on extension cords run through doors or windows to power the house during an outage
  • The home has a well pump, sump pump or medical equipment that must keep running
  • A portable generator is in use and you want a permanent, safer connection
  • The home has a fuel supply, such as natural gas or propane, that can feed a standby unit
  • A home office or business needs power to continue during an outage

What the pro does

  • Survey the home's load and decide which circuits the generator will carry, then size the unit to that load
  • Prepare a level, approved pad and a location that keeps exhaust away from doors, windows and vents
  • Install the transfer switch or inlet, and wire it so the utility and generator can never be connected at the same time
  • Run the fuel line with the correct pipe size and a shutoff, and test it for leaks before the unit is started
  • Connect the generator's control wiring, battery and any remote monitoring, and set the start and transfer settings
  • Run a full load test and a utility-loss test, then schedule the inspection and show the customer how to operate the unit

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Generator size needed for the circuits the customer wants to keep running
  • Standby or portable-connection type, and whether the unit is permanent or moved
  • Fuel type and the distance to the fuel source, such as a gas meter or a propane tank
  • Transfer switch type and the number of circuits it covers
  • Concrete pad, exhaust clearance and site preparation needed for the location
  • Permit, inspection and utility notification requirements

What a written quote should spell out

  • Generator size, fuel type and the circuits the unit will carry
  • Transfer switch or inlet, and how the utility and generator are kept separate
  • Fuel line size, shutoff location and the leak test performed
  • Pad, exhaust clearance and site work included
  • Load test, utility-loss test and the inspection responsibility

Questions to ask before you hire

  • How did you decide which circuits the generator will carry?
  • Will the transfer switch prevent backfeed into the utility line, and how is that tested?
  • What fuel line size do you use, and who checks it for leaks?
  • How far is the exhaust from doors, windows and vents, and how did you choose the spot?
  • Who pulls the permit and arranges the inspection for the fuel and electrical work?
  • Will you run a full load test and show me how to start and stop the unit?

Red flags

  • Offers to power the house through a dryer outlet, a back-feed kit or a cord with no transfer switch
  • Places the generator where exhaust can reach a window, door or air intake
  • Connects the fuel line without a leak test
  • Skips the utility-loss test or says it is not needed
  • Sizes the generator without listing the circuits it will carry

What you can do yourself

Choosing the generator size, planning the outage plan, and keeping a fuel supply stored safely outdoors are reasonable. Never run any generator indoors, in a garage or near a window or door, because carbon monoxide can kill. Connecting a generator to the house, backfeeding a dryer outlet, and running fuel lines are not safe to do yourself, because the utility line can be energized. Have a licensed electrician install the transfer switch and a qualified installer handle the fuel work.

Licenses and permits

Generator installation is commonly done by licensed electrical contractors and, for gas or propane work, by a licensed installer for that fuel. A permit and inspection are often required. Check with your state or local licensing agency and building department for the rules that apply to both the electrical and the fuel work.

Generator installation questions

Can I plug the generator into a dryer outlet?

No. That sends power back into the utility line, which can injure a utility worker, and it can overload the house wiring. A transfer switch or an approved inlet with a transfer switch is the safe method.

Does a standby generator need a fuel line?

Most standby units use a fuel line from a gas meter or propane tank. The line must be sized and tested for leaks, and it must have a shutoff the installer can reach.

How long does a generator take to take over after an outage?

That depends on the unit and the transfer switch. Ask the installer for the expected transfer sequence in writing, and test it during commissioning.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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