What Is a Transfer Switch?
A transfer switch is an electrical device that switches the power source from the utility to a backup generator during an outage. There are two main types:
According to a Transfer Switch Market report, the industry is expected to grow significantly in the coming years.
Manual Transfer Switch: Requires someone to physically switch from utility to generator power.
Automatic Transfer Switch (ATS): Senses power loss and automatically switches to generator power.
Why You Need a Transfer Switch
Safety: Prevents backfeeding, which can electrocute lineworkers and damage your appliances.
Compliance: Many local electrical codes require transfer switches for legal generator installation.
Convenience: Allows you to control specific circuits, avoiding overloads and optimizing power use.
Tools and Materials Needed
UL-listed transfer switch (manual or automatic)
Compatible generator
Circuit breakers (if not pre-installed in switch)
Electrical conduit and fittings
Heavy-gauge wire (per local code)
Screwdrivers, wire strippers, and drill
Voltage tester or multimeter
Personal protective equipment (PPE)
Safety First: Key Precautions
Turn off power at the main breaker before beginning any installation.
Verify local codes and permits: Some areas require a licensed electrician or inspection.
Use protective gear such as gloves and goggles.
Avoid DIY if you're not confident with electrical systems—hire a certified electrician.
Step-by-Step Installation Guide
1. Plan Your Load
Decide which circuits you want powered during an outage (e.g., refrigerator, lights, internet). A transfer switch usually supports 6–10 circuits.
2. Choose the Mounting Location
Mount the transfer switch close to your main electrical panel for easy wiring. Ensure it’s in a dry, accessible location.
3. Shut Off Main Power
Before wiring, turn off the main breaker. Use a voltage tester to ensure power is completely off.
4. Install the Transfer Switch
Attach the switch to the wall using screws and anchors. Drill knockouts and attach conduit from the main panel to the switch.
5. Connect the Wires
Run wires from the transfer switch to the corresponding circuits in the main panel. Typically, each circuit wire from the panel is removed and replaced by wires from the transfer switch.
Important: Label each wire clearly and connect ground and neutral wires according to the manual and local codes.
6. Connect to the Generator Inlet Box
Install a generator inlet box outside your home or business. This is where you’ll plug in the generator. Connect it to the transfer switch using the proper gauge wire and conduit.
7. Test the System
With the main power off and the generator running, flip the transfer switch to test that each selected circuit is powered. Monitor for any issues like flickering lights or overloaded circuits.
After Installation Tips
Regularly test the system, especially before storm seasons.
Keep a load plan handy, so anyone using the generator knows which appliances can be powered.
Schedule inspections or maintenance annually if the system is rarely used.
When to Call a Professional
If you’re unsure about electrical code compliance, load balancing, or wiring techniques, hire a licensed electrician. A professional can ensure a safe, legal, and efficient installation.
