How to Wire a Generator to a Breaker Box

Home generators can be intimidating to get set up, but that emergency backup power from a generator can be essential, particularly in times of crisis when the main power grid in your area goes down. When that happens, you will be glad you put in the effort to learn how to wire a generator to a breaker box! But the process of installing a generator safely and securely is a lot more complicated than just running a few power cables from your generator to your home, and it is important to learn how to do it properly.

Here at Best of Machinery, we have put together a guide to how to get a generator set up safely to provide power to your home in the event of an emergency. Just follow the steps of our guide below, and you should be able to get your generator set up quickly, easily, and safely with no issues at all!

How to Hookup Generator to House

The most important thing to remember when you are trying to attach your generator to your home is that you must never use a simple cord to plug your generator straight into the main socket panel. The power created by a generator is too high for this, and it can cause a high risk of damage and overload to your circuit and the local electrical grid. If you do this without disconnecting your main breaker from the circuit, it could electrocute anyone working on power lines nearby, risking their lives.

It is also a major fire hazard, an electrical code violation, and an illegal action in most places. In short: don’t do it! Let us take a look at the steps you will need to follow in order to wire your generator to your breaker box safely and responsibly, restoring power to your home without risking your life or your safety.

Step 1: Determine Generator Plug Type and amperage

The first major task when you are hooking up a generator to your breaker box panel is to work out what you are dealing with and what you will want to use to get things set up. You are going to need to know the amperage and the plug type of your generator power system. If you have got a generator with a big round power plug, that provides 220V of power and will power both sides of your breaker box.

Somewhere near the plug, you should be able to see the amperage. The most common types are the 20 amp Nema L 14 20, the 30 amp Nema L 14 30, and the 50 amp Nema CS6365.

Step 2: Gather your Tools

To safely attach your generator to your home breaker, with or without a transfer switch, you will need to have the right selection of tools to use for this. The first and most important element is a transfer switch, or a breaker interlock kit if you can’t get hold of one of these. Make sure that this fits your specific breaker box, and that it is officially UL rated for safety and reliability!

You’ll also need a 2 pole double breaker with the same amperage as your generator. Again, you will need to make sure you buy one that fits your breaker box, as they are not all interchangeable. A power inlet box that matches the amperage of the rest of your gear is also important. You need to make sure that the circuit uses the same level of amperage and power in every component!

The last bits you will need are at least 10 feet of 10 gauge electrical wire, a sturdy conduit body, waterproof conduit glue, and an extension cord (or extension cords) that corresponds to the main amperage of the rest of your circuit.

Step 3: Access Holes

You might already have an access hole drilled in your exterior wall for this sort of project. If you don’t, then you will need to drill one now, as you are going to have to use it soon. A powerful drill such as a hammer drill can make your life much easier here! Try to get your conduit access hole as close to the main panel as you can – this will make it much easier to use when the time comes!

Step 4: Mount your Power Inlet Box to the Wall

Start by taking the front cover off your power inlet box. Remove one of the knock out points and attach the PVC fitting. If there are any gaps, use waterproof glue to seal everything up close. Then, once you have done that, you can mount the whole box to the wall using standard tap connectors.

Step 5: Setting up the Conduit

Use a hacksaw to cut your conduit to the right length. It will need to stretch from the inlet box to the access hole without any gaps. Take your time here, and make sure you get your measurements right. Don’t use any glue on it until you are certain that it will fit properly! Once you are sure that you have managed to cut the conduit tube to the right length, you can use glue to attach it properly to your main wall.

Step 6: Wiring up the Generator Inlet Plug

Once you are sure that all of the glue has dried completely, you can start to work on the wiring to transmit power. Remove the cover from the main body of the conduit. Pull the wires through the conduit one at a time, attaching each one to the plug as you go rather than letting them all get tangled up at the end. Remove a little less than an inch of insulation from the end of each wire in order to fasten them properly. Once you have got them attached, use a larger flat screwdriver to tighten up all the terminals.

The wires attach as follows: The green wire is the ground wire and attaches to the main power inlet box. The white wire is the common wire and attaches to the W terminal. The black and red wires are load wires and attach to the X and Y terminals. Once you have done that, push the wires out the other end through the conduit and into the house, one at a time.

When you are confident that they are properly poking through into the interior, replace the cover on the conduit body, making sure that the gasket fits the panel properly. If there are any gaps between the conduit and the wall, use silicone or expanding foam to fill the gaps completely.

Step 7: Prepare the Circuit Breaker Box for Power Wires

Start by turning off all of the branch circuit breakers as well as the main power breaker. Then, take out the four screws holding the front panel onto the breaker box. Remove one of the knockout panel parts and screw in a conduit adapter, making sure it fits tightly. Then, simply pull the wires through the conduit and into the breaker box itself. If you are using an interlock, then you will need some space in the upper right corner of the breaker panel.

You will probably need to move one or two breakers down the main panel a bit – hopefully you will have enough loose wire for this, but if you don’t, then you can use a short piece of insulated wire as a sort of small extension cord. If you do this, make sure you don’t attach copper and aluminum wires to one another, as they can corrode over time. You will need a wire splice to do this safely!

Step 8: Install Wires and the Generator Power Breaker

Now you have freed up some space, you can install your new circuit breaker or transfer switch in the top right corner. Attach the red wire to one terminal on the breaker or transfer switch and the black wire to the other terminal. The white wire attaches to the common bond rail in the circuit breaker box, and the green wire attaches to the matching ground rail.

Next, you will need to use a retaining bracket to make sure the breaker can’t come loose. There should be a visible retaining bolt somewhere in the box that you can use to attach the retaining bracket. Once you have closed everything up and checked that your generator is properly connected, you will be ready to power everything up and get moving again!

How to hook up a Portable Generator to a House

Portable generators are actually quite easy to wire up to your house. If you are planning to use a portable generator to power a house, then you will need to make sure you have got a transfer switch and a gen cord available.  A gen cord is essentially a special extension cord designed to be used for a generator. Don’t try to use a standard extension cord for a portable generator transfer switch installation!  All you need to do is to plug one end of your gen cord into the portable generator itself, and the other one into the transfer switch.

Then, start the portable generator. Once you have got the generator running, turn your attention to the transfer switch. You will need to flip every main breaker in the switch from the setting marked “line” to the option marked “generator.” Then, activate each circuit you want to power up, and you will be ready to get your appliances up and running!

How to Connect Generator To House Without Transfer Switch

If you don’t have a transfer switch available but still want to work on hooking up a power generator to your home circuit system, then you will need some additional tools, but it should still be doable. Just remember, you can’t simply plug a generator into your mains system without a transfer switch! We’ve got a short step-by-step guide to installing a generator without a transfer switch. Let’s take a look.

Step 1: The Appropriate Tools

The most important thing you are going to need for hooking up your generator to your house without a transfer switch is an interlock kit. This is a vital tool, and you will need to make sure that you’ve bought the model of interlock kit that perfectly corresponds to your model of generator. To go with this, you will also need a breaker. Check your generator specifications before you buy one to make sure you get the right one. There aren’t too many options to choose from, though, and in most cases, you will be fine with a standard two pole double breaker and 30 amp power supply.

You are also going to need at least 3 sets of 10 foot long 10 gauge electrical wires, ideally all in different colors to make it easier to keep track of which is which. You will also need a full set of standard DIY tools, which you probably already have lying around in your house somewhere.

Finally, you will need all of the appropriate safety equipment. That means that at the bare minimum, you are going to want to make sure you have sturdy, strong work gloves, durable rubber-soled work boots, and a good set of protective eyewear to keep yourself safe while you work.

Step 2: Drilling Holes in the Walls

In order to get your generator set up without a transfer switch, you will need to be able to run power wiring from the outdoor generator to the circuit system inside your house. That means you will need to drill a hole through your external wall to pass the wires through. Try to keep that hole some distance away from the generator for safety reasons – 6 feet or so should be enough. You can use a hammer drill to break through the wall if it is a particularly sturdy wall.

Step 3: Setting up your Generator to a powerhouse with no transfer switch

First, set up your inlet box on an exterior wall. You will want it to be a few feet away from the generator itself. Attach that to the conduit, and seal up any holes to make sure everything around the inlet box is entirely watertight. Then, it is time to wire up the generator inlet plug. Pull wires from the main body of the conduit one at a time, and fix them to the plug.

Once you’ve tightened everything up with a screwdriver, it should be secure and safe to use. Next, it is time to get the breaker box set up. Turn off the main breaker and everything attached to it, and just push the wires into the breaker box. Then add the breaker retainer, and you are almost finished. Once you have put the cover back on the breaker box, you will be ready to go!

Conclusion

Setting up a generator is a complex and time-consuming process, but if you are patient and careful and make sure that you follow all of the steps above, you should be able to get it finished without too much difficulty. Even if you have no major DIY experience, this is still a task that should be possible to do at home. If you are worried about doing it wrong, though, it is always much more sense to hire a professional to set up your electrical systems safely and securely than it is to attempt to do it yourself and wire things up improperly!