Planning a Manual Transfer Switch Installation

The modification of your home’s electrical system requires a building permit and an inspection. Before planning your transfer switch installation, consult with your local building and code enforcement department to determine local installation requirements and building codes. Most will require a specific plan that includes a materials list before issuing a permit.

Manual-Transfer Switches

During a power outage, the generator is started and plugged into the transfer switch.

A manual transfer switch connects your home’s electrical system to a portable generator for use during a power outage. A portable generator is not designed to power your entire home, but it can provide electric current to specific circuits you choose to power with your generator. The transfer switch isolates those circuits from the utility company which prevents your generator from endangering utility worker lives. It also provides a degree of overload protection for your generator by limiting the circuits connected to it. At the same time, your neighbors won’t be inadvertently drawing power from your generator, another possible source of overload.

Installation Overview

A new, double-pole, 240-volt circuit breaker inside the main service panel supplies power from the electric utility to the transfer-switch utility breaker. Another breaker in the transfer switch connects to the generator. The two breakers are mechanically connectedturn either one on, and the other one turns off. This prevents both breakers from being in the “ON” position at the same time.

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Now part of Generac Power Systems, Inc., Gen/Tran is the leading designer and manufacturer of manual and fully automatic transfer switches for backup power applications up to 50 kW. Transfer switches, now required by the National Electric Code, connects to the circuits in your electrical panel that you’ll need most during a power outage, like a furnace, lights, well pump, television, garage door opener, etc.

Circuits which will receive power from the generator during an outage are disconnected from the circuit breakers inside the main service panel or load center, and reconnected to circuit breakers inside the transfer switch.

The generator itself is not permanently hardwired to the transfer switch. Instead, it connects to the transfer switch through a four-wire power cord that plugs into an inlet box. The inlet box is permanently wired to the transfer switch. This allows you to disconnect and store the generator when it is not in use.

Equipment Locations

The location of three pieces of equipment are important for installation.

The generator must sit outdoors where its exhaust will not enter the home. All internal combustion engines produce deadly carbon monoxide. Determine a location with a solid base for the generator to sit on where exhaust fumes cannot be drawn into the house through fans, windows or ventilating equipment. Remember that in a power emergency, you may need to open windows if your air conditioner is not working.

Locate the inlet box where the power cord from the generator will reach it and as close to the transfer switch as possible to simplify running electrical conduit and wiring. Norwall Power Systems supplies manual transfer switch kits with either 10 or 25 foot cords to give you plenty of room for choosing a generator and inlet box location.

Plan to mount the transfer switch on either the left or right side of your main distribution panel. This makes connecting the transfer switch to the utility power and moving existing circuits to the transfer switch easy. If you purchase a prewired transfer switch, the distance to the main panel is limited by the length of the flexible conduit and transfer switch wiring harness.

Choosing Critical Circuits

Your portable generator won’t power everything in the house, and you’ll have to choose which circuits will receive power. Some appliances at the top of the priority list include furnaces, refrigerators, freezers, sump pumps, well pumps, a kitchen outlet, medical equipment and a lighting circuit. Choosing what to power depends partly on your local climate. Furnaces are more important in the north than in the deep south, for example.

Of lessor importance are central air conditioners, televisions, computers and other conveniences. Your main goal is to provide power to essential circuits that protect your home and keep you safe during a power outage. If large air conditioners are essential to your needs, a larger, standby generator may serve you better and manage your emergency power more efficiently.

Continue reading with Choosing Materials.

*To help make sense of your power situation, consult a licensed electrician before beginning any work.

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