How to connect an electric generator to a house electric system

Written by chris deziel Google
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How to connect an electric generator to a house electric system
Install a transfer switch before you connect a generator to your panel. (Nicholas Eveleigh/Photodisc/Getty Images)

If you live in a rural area, wiring a backup generator to your house panel can keep your water pump and other life necessities working in the event of a power outage. To accomplish this task safely and legally, according to the Pacific Gas and Electric Company (PG&E), you must install a transfer switch that disconnects your house from the power lines while the generator is running. This protects repairmen working on the power lines and also protects the generator in case the power comes back on while it's running.

Skill level:

Things you need

  • Transfer switch
  • Screwdriver
  • Electrical cables

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  1. 1

    Disconnect your panel from the power lines. You may be able to disconnect the wires from your electric meter, or you may have to call the power company and ask a representative to temporarily disconnect the power to your house. If you're not sure how to proceed, consult a licensed electrician.

  2. 2

    Install a transfer switch near the panel. According to PG&E's recommendations, it should be a double-pole, double-throw switch capable of handling two 120-volt service cables. It's double-pole because it powers two circuits at the same time, and double-throw because it's not a simple on/off switch, but a switch that connects one electrical path while disconnecting the other. Screw the switch securely to a wall or framing member.

  3. 3

    Disconnect the red and black service lines from the panel and feed them into a knockout hole on one end of the switch. Connect each cable to one of the brass lugs near the hole by unscrewing the lug with a screwdriver, feeding in the cable and tightening the lug.

  4. 4

    Feed two cables through the knockout hole in the centre of the box and attach them to the switch's two common terminals. Run these cables back to the panel and attach them to the brass lugs from which you removed the service cables. Use cables that are the same size as the service cables.

  5. 5

    Feed two more cables through a knockout hole in the end of the switch opposite the one through which you fed the service cables. Attach these cables to the remaining two lugs, run them to a permanent standby generator, then connect them to the generator's brass service terminals. Size the cables that you run to the generator in accordance with local ordinances. The city of Roseville, Calif., for example, specifies 10-gauge cable as a minimum.

  6. 6

    Set the switch so the power lines are connected, then turn the power back on to energise the panel. Whenever you want to use the generator, flip the switch to disengage the power lines and engage the generator before you turn it on.

Tips and warnings

  • You can use a similar procedure to connect a portable generator. It may be too small to energise your entire house, but you can use it to power essential circuits. The procedure is easier if you install the breakers for these circuits in a subpanel and install the transfer switch between the subpanel and the main panel.
  • PG&E; recommends calling the power company after you've installed the switch so the company can make a note of it and alert linesmen who may be working in the area to its existence.
  • Check your local codes. Many require a transfer switch to be installed by a licensed electrician and may also require an inspection.

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