How to Connect a Generator to Your Tiny House Without a Transfer Switch

How to Connect a Generator to Your Tiny House Without a Transfer Switch

House generators are quite expensive. Therefore most homeowners try to cut down costs wherever possible, bypassing the recommended installation procedure. Ideally, connecting a generator to any building with a grid supply requires a transfer switch for safety. But the material and labor cost of installing a transfer switch is about $500 to $1,500. So even a DIY generator electrical switch is pricey for some. 

So many try to find other ways to connect a generator to a home without a transfer switch. The easiest way to connect a generator to your house without a transfer switch is via an extension cord running from the generator into a designated receptacle in your house. Similar to other electrical work, this setup requires electrical knowledge and skills. 

This article will discuss in detail how to connect a generator to a house without a transfer switch if necessary.

What is a transfer switch?

A transfer switch(both manual and automatic) acts like a mini circuit breaker panel. It is an electrical device that allows safe power connection and disconnection from different sources to an electric load. It is a device located. 

The utility-to-generator transfer switch(generator transfer switch) keeps the grid power separate from the generator supply so that only one of these sources can power your electric load simultaneously. It also prevents power from flowing in the wrong direction, such as from home and into the power grid(back feeding).

There are a couple of reasons why using a transfer switch is necessary:

  • First, it is a requirement by the National Electric Code to have a properly-installed transfer switch when you use a generator to power your home’s electrical panel.
  • In other circumstances, a transfer switch is a safety necessity. It prevents electrical fires, physical harm, and damage to your electrical equipment. This is because the transfer switch controls the current and prevents power surges and back-feeding of the grid, thus endangering the lives of power utility workers. 
  • A transfer switch prevents the grid power from coming into contact with the generator, which may likely burn it out. 
  • It adds convenience by preventing the need to connect individual appliances to your generator every time you need it. Therefore it makes the connection to the generator efficient by removing the need for extension cords. Without the transfer switch, you’ll have to connect multiple outdoor extension cords from your generator to your house. Using extension cords will increase the risks of fire or electrocution.

Can I run a generator without a transfer switch?

Technically, you can connect your generator directly to your house’s breaker box without the transfer switch. However, transfer switches are essential if you plan to power a house with a generator for an extended period. With a transfer switch, generators can damage the power lines, injure people, and pose an indoor fire hazard. 

Also, without the transfer switch, you won’t be able to power hardwired appliances like the furnace and AC, only electronics with a standard plug. 

Although most electricians do not recommend connecting your generator directly to your home without a transfer switch, it may be necessary for some circumstances. For instance, you can forgo a transfer switch if you want a temporary generator connection to power smaller appliances such as lamps or refrigerators during a power outage.

Alternatively, you can use a power inverter instead of a transfer switch. A power inverter is a device that transforms DC power from the generator into AC power that your home appliances can utilize. Power inverters have a built-in transfer switch that you need to reset for them to work. The power inverter will also automatically shut off power from the generator when power from the grid resumes. 

Can I just plug a generator into an outlet?

You should never plug a generator into a wall socket in the house unless the outlet is set up specifically for the generator. The outlet should not connect to the main electrical panel or grid.

Although it is physically possible to plug a generator into a regular outlet, several risks are involved. First, it can cause back feeding, redirecting unfiltered current in the wrong direction. This can cause permanent damage to the electrical system and increase the risk of electrocution. 

Furthermore, connecting a generator to a tiny house through a dryer outlet is illegal in the USA, and insurance companies will not cover the damages to the homeowner’s property. Since typical wall outlets have no breakers, you risk your house catching fire, or your generator and other connected appliances could catch fire when power resumes. 

Do I need a transfer switch for a portable generator?

Portable generators do not always need a transfer switch, but it’s a good precaution against electrocution. Another benefit of the transfer switch in a residential home is powering appliances via your circuit breaker panel instead of using extension cords. 

The transfer switch also allows you to run hardwired appliances such as the dishwasher, AC, ceiling fans, and water heater. But if you’re using a portable generator to power a few appliances directly into the generator, then a transfer switch is not necessary.

However, if your portable generator is rated 5,000 watts and above, you must use a transfer switch for safety and efficiency. Due to the high levels of power such a generator produces, the transfer switch acts as a regulator to help prevent surges and backfeeding the grid. 

How to connect a generator to your tiny house without a transfer switch

Before we start, it’s essential to know that there is no secure way to use a generator without a transfer switch. Although it is technically possible, a transfer switch ensures the safety of the people in and around your home, your generator, and your electrical appliances.

But if you’re stranded without grid power, here’s how you can legally plug a generator into your house without a transfer switch.

Things you’ll need

  • Double outlet receptacle kit
  • Three-prong plug and wire(red, black, and green)
  • Waterproof outlet cover
  • Power consumption watt tester
  • Extension cord
  • Pliers
  • Screwdrivers
  • Electric tape
  • Drilling machine
  • Sealant
  • Safety gear


Safety precautions

  • First, switch off the main circuit breaker to your house to prevent electrocution and allow you to work on your house safely. You can also shut off the power at the main source if possible.
  • Put on your protective gear; work boots, gloves, and protective eyewear. 
  • Turn off the main breaker. It is labeled ‘MAIN.’ If there are no labels, turn off all the breakers to be safe.

Make space for the outlet utility box and receptacle

  • Find a suitable location on the outside wall of your tiny house to install an outlet utility box for your generator. Pick a location that is easily accessible outside and inside of the house.
  • Trace the size of the outlet on the inner wall.
  • Then use an oscillation tool to create a rectangular space for the outlet.
  • Insert the outlet box and screw it securely on the drywall.
  • Use a drill to make a hole through the wall to run your wires from the outside.
  • Mount the waterproof utility box on the opposite side of the wall.

Route the wire through the wall

  • Run the three-prong extension cable through the wall from the outside and into the house. 
  • Pull a minimum of 6 inches of wire through the utility box.

Wire the receptacle

  • Use a utility knife and strip the inner cable jacket to expose three wires.
  • Use wire strippers to strip about 6 inches of insulation off each wire.
  • Then use the wire strippers to pinch the end of the exposed wire and bend it to make a hook.
  • Wrap the black wire around the brass screw, the white wire around the silver screw, and the copper wire around the green screw on the outlet.
  • Wrap electrical tape around the exposed parts of the wires. 
  • Then install the receptacle on the inside and secure it in place.
  • Once you connect the wires to the receptacle, apply sealant on the outside and inside of the knockout.

Connect the generator wire to your outlet utility box

  • Connect the extension cord coming from the outlet to the generator inlet plug.
  • Turn on the main breaker switches, start your generator and test the receptacle.
  • Plug your cord into the generator receptacle and use a voltage meter to verify power. The reading should be 120V. 
  • Now you can start powering some of your essential appliances. It’s imperative not to overload your generator with capacity beyond its wattage rating to prevent damaging your generator and extend its lifespan. 

The downside to the above setup is you can only connect power home appliances with standard plugs. So you will be unable to run any hardwired appliances as the generator is not connected to the home’s electrical panel. And unfortunately, connecting a generator directly to the panel without a transfer switch is dangerous and illegal. 

Check this too: Do I Need to Ground My Generator When Camping


Although the guideline will help you connect a generator to your house without a transfer switch, we recommend getting an electrician to install it. A transfer switch is a safety device that prevents the effects of backfeeding and allows you to power hardwired appliances in your house. If you can’t DIY a generator to your home without a transfer switch, it’s best to hire a professional electrician.