How to Wire Two Transfer Switches to One Generator

A transfer switch is essential for the installation process of a generator. It will be both a safety hazard and a fire hazard if you connect the backup generator directly to the main power panel of your home. Also, without circuit breakers, the generator will not distribute the power evenly.

That said, if you want to power two homes or two panels without going through the expense of getting two standby generators, you should know how to wire two transfer switches to one generator.

And whether you want to opt for an automatic transfer switch or a manual transfer switch, you will get to know all about the process by going through this article. We have tons of hands-on experience with transfer switches, and we know the most proper and safest installation procedure. So, let us get into it, shall we?

Why Would You Need to Install Two Generator Transfer Switches?

Before we get into describing the process, we would like to ensure that you know the basics. So, why would you need to install two manual or automatic transfer switches into one standby generator? First of all, modern electrical requirements exceed what the average homes required 20 or 30 years ago.

For example, a single-family home would have a minimum requirement of 100 amps. Some will even have more than 125 amps and would require at least 150 amps. And it would require a substantial amount of generator power to ensure proper flow of electricity during the power outage on those homes.

Yes, even if you opt for compatible transfer switches or automatic transfer switches, you would need more space to work with. But the cost advantages outweigh this small disadvantage. What cost advantage are we actually talking about here?

Well, for example, if you have got a Generac generator with one switch and want to connect in a well pump and your home at the same time, you would need to get another generator. But with the two switches, you can get two wires out of the generator.

With that, you can connect to the main breaker of the pump and one panel of your home without having to spend the extra cost.

How to Install Two Automatic Transfer Switches to a Single Generator?

Some manufacturers, such as Generac Tech, will not provide any instruction regarding the control wires, service panel, and other required factors to install two switches.

If you know what you are doing, you would not have to rely on an electrical contractor just to figure out the wiring diagram of the main breakers. Do not believe us? Follow these steps:

Step 1: Select the Most Compatible Transfer Switches

First and foremost, you should check the manufacturer’s recommendation. It should state which generator transfer switch you should be using to connect the main panel. Sometimes, the manufacturer will even go ahead and state the installation process of the ground wire with the standby generator.

For that reason, you should go through the entire manual and find out each and every detail about the switch installation process.

Step 2: Install One Transfer Switch for Each Panel

As the name of the process states, you would need 2 switches. One for the main panel and the other for the sub-panel. Ensure that the transfer switch meets the rating for the main panel. You can check with a utility meter if you want to. And it would connect to one of the circuit breakers of the panel.

Then, work with the second switch for the secondary panel. Follow the same process and pair both the switches together. However, note that the main switch will not start up if connected with the line-side power.

Now, if you want to feed a double pole in the same conduit, you would need to route your wires accordingly. If there is a flaw in the wiring, accidents are bound to happen. So, you should be extra careful while wiring the switches.

Step 3: Test Things o098ut

Finally, you would need to check whether the switches are working adequately or not. If possible, connect one of the terminals with a battery charger and a utility sensing tool. That would allow you to check the voltage. If everything seems right, you can start the generator and see if it can power the panels or not.

Things to Consider Before Installing 2 Switches

Before you do carry out the entire process, there are some things that you would need to consider. First of all, the switches must have the Service Entrance rating. It will often be denoted as SE, and without this rating, it would not be safe to pair them up with a single generator.

Secondly, if you want to power a 200-amp panel, for example, you would need to connect a 400-amp main service disconnect. This will only be applicable if you are working with a Service Entrance Disconnect.

Disadvantages of 2 Switches for a Single Generator

As we have mentioned above, the primary disadvantage of getting 2 switches installed is that you will need more space. So, you would need to have a proper working area available around the generator. But that is an easy fix. You could just install the switches on a wall that is beside the generator.

Secondly, you would need to ensure that the switches are compatible with the generator. And this can become a bit tough depending on the model of the generator. But with patience, you can surely get your hands on both switches that are compatible with the model.

Final Words

As you can see, learning how to wire two transfer switches to one generator is pretty straightforward. You just need to do the wiring right and get yourself the proper switches.

The cost advantage you will be getting after carrying out the installation surely makes it worth it. It will be much cheaper than getting two separate generators.

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