How to Wire a Portable Generator | Ask This Old House

24February 2020

Ask This Old House master electrician Heath Eastman explains a few different methods for wiring a portable generator to a house.

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Time: 1-2 hours

Cost: $500 and Up

Skill Level: Professional only

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Portable generator

1. Heath explains some of the ways that a portable generator can be professionally wired to a house.
2. First, never place the generator indoors or in a garage, as it generates carbon monoxide and is fatal. Always place it just on the outside of the house.
3. Most generators can be plugged into a power inlet box, which an electrician can then wire into the house and connect to the electrical panel.
4. Connecting to the electrical panel can be done in two ways:
a. The electrician can install a manual transfer switch, which connects to a selection of circuits that are most likely to be needed even when the power is out. Then, in the case of a power outage, the transfer switch can be powered on.
b. The electrician can also switch out the main breaker and an additional double-pole breaker with an interlock device and wire the generator directly to that. In the case of a power outage, simply lift the interlock lever, power the generator on, and then select the circuits you want powered on. This allows for more flexibility to use only the things you actually need in the case of a power outage.

Heath first showed a manual transfer switch, which designates specific circuits to be powered in the event of an outage and has to be manually switched from utility power to generator power.

He also showed an interconnect switch, which wires to the main breaker panel and allows the entire panel to be energized by the generator. Both of these should only be installed by a licensed electrician and can be purchased from an electrical supply house.

Heath showed the GP6500 COSENSE portable generator, which has a built-in carbon monoxide detector and is manufactured by Generac (

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How to Wire a Portable Generator | Ask This Old House

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