Why Is My Generator Only Powering Half The House?

Generators are a necessity, especially in areas with occasional power interruptions. These secondary electricity providers provide reliable and efficient service, making your home comfortable.

Like other machines, generators can develop faults and provide insufficient power to your house. We understand why this happens and have consulted technicians, and here's their reply. 

The most common issue that can cause your generator to power only half of the house is a faulty transfer switch and circuit breaker.

A generator that has a severe issue should be taken to an electrician to avoid further damage. 

Apart from learning why your generator only powers half the house, there are many other factors you need to know about generators and how to maintain them properly, so stick around and keep reading to learn more.

Female hand starts a portable electric generator standing on the grass in front of a summer house in summer evening - Why Is My Generator Only Powering Half The House

Reasons Your Generator Only Powers Half The House

When your generator begins to fail, it should be repaired immediately to prevent further problems. The various reasons that can cause your generator to only power half the house relate to minor issues that can be resolved with proper maintenance and regular inspections.

A professional should do this unless you think you can DIY it. Here are the top reasons why your generator might only power half the house:

Faulty Circuit Breaker

The electrician on hand open circuit breaker board. Selective focus.

Circuit breakers are used to safeguard electrical circuits against harm brought on by overcurrents or short circuits. Imagine getting a 1kw generator and trying to use it to power a microwave. You will most likely trip a circuit breaker.

Circuit breakers serve as a way to prevent you from overloading your generator and also prevent shocks from electrical leaks. The circuit breaker is usually involved in most cases of half power supply in houses.

This results from one bad breaker and the other breaker only allowing 1 phase of the 240V power through. You will need an electrician to replace the breaker to fix this issue.

Check out this Haozheng miniature Circuit breaker on Amazon.

Transfer-switch not working

Transfer switches are used to move load between two sources [utility and generators in most cases]. They are similar to the change-over switch, which is more like the manual transfer switch.

The automatic transfer switch is more efficient and requires no assistance to switch the load as it is done automatically.

Sometimes, the transfer switch could be the problem of the partial power in your house. Automatic transfer switches have been known to fail due to transient voltage.

If for some reason, the voltage in your house isn't the appropriate 240v, your transfer switch might develop an issue leading to half power.

Check out this Geepkey transfer switch on Amazon.

How Can You Fix Generator Powering Only Half The House?

The first step to fixing a problem is knowing its causes. After you must have found the reason behind the power failure, the repair would depend on the cause of the half power.

There are so many fixes for this problem; you should probably try as much as possible to ensure you are not missing the right fix. Here are some of the top fixes for – a generator powering only half the house.

Female hand starts a portable electric generator standing on the grass in front of a summer house in summer evening


The first solution to this problem is discovering where the voltage got lost. Get a voltmeter and trace it back to the hot leg without voltage.

Generators give out a voltage of 240v, which is shared into two equal volts of 120v each and circulates around the house. 

After discovering the area where the voltage got cut, you could call an electrician to help rectify the issue. 

While tracing back, ensure that the issue isn't from a bad wire connection at the generator or switch.

Replace Relays

Repairing or replacing relays depends on the electrician's advice, as one failing could indicate the other is also wearing out. 

Replace Main Breakers

A faulty main breaker would allow only one phase power of the 240v required. Luckily, getting this done isn't too pricey, and it is relatively easy to do.

Replace The Contractor Assembly

Replacing the contactor assembly should be the next line of action if the problem is from the transfer switch. Unfortunately, these fixes cost more than the others and can be time demanding.

 DIY is good, especially if you are trying to save cost, but you might discover in the long run that calling an electrician could have saved you a lot more – even by spending a little more money on labor.

What Controls The Voltage In A Generator?

Gasoline Portable Generator on the House Construction Site. Close up on Mobile Backup Generator .Standby Generator - Outdoor Power Equipment

 Many parts perform different functions in generators, making them a good alternate source of power when there is a surge in power.

The part of the generator that controls voltage is known as the voltage regulator. It is responsible for regulating the voltage being passed into your home.

The voltage regulator converts AC input voltage from the generator into DC {Direct current].

The generated DC is sent to secondary windings in stators known as exciters which are responsible for converting the DC to AC. 

Voltage regulation in a generator simply involves converting back and forth between DC and AC until the generator begins to produce an output voltage equal to its operating capacity.

When a load is placed on the generator, the voltage dips, and the voltage regulator begins the conversion process again until the output voltage is at its operating capacity. 

Do All Generators Have Automatic Voltage Regulators?

Portable electric generator on the green grass outdoors in summer

AVRs (Automatic Voltage Regulators) are essential in every generator as they ensure effective functionality even during power outages.

A generator without an AVR is susceptible to sparks and fluctuations in power.

When there are sparks and fluctuations, home appliances and devices could be affected by developing faults.

Every generator has its type of AVR. When you see how important AVRs are to your generator's functionality, go for the best when it comes to AVR in your generator. 

Luckily, you could always change or install a new AVR for your generator if it either gets spoilt, or you feel that the AVR is not quality enough to ensure the safety of your appliances.

Where Is The AVR Located In A Generator?

Locating the AVR in your generator is not something so difficult to do, though it could differ depending on the type of generator you use.

You should know where your AVRs are to be able to change or repair them when the occasion calls for them.

The AVR of a generator can be found in one of these three major places depending on the type of generator.

  • Main control box of the generator
  • Alternators terminal box

Under Alternators real cover [these usually apply to portable generators only].

Check out this VQL AVR on Amazon.

What Is An Exciter In Generator?

An exciter in a generator is a DC generator relay responsible for converting DC generated from the AVR into AC for the main generator rotor. It is manufactured from copper and electrical steel primarily. 

How Do I Test A Generator Exciter?

Electric AC generator alternator, isolated on white.

To test a generator exciter,  you can do so only when the generator is off. Testing is not a very hard job to do. They can be done DIY or with the help of a technician. Here's the procedure to follow:

Use Of Safe Electrical Practices

Efforts should be made for best electrical practices to be used for safety purposes.

Disconnect Specific Wires

The red and black wires are the exciter F+ and F - wires and should be disconnected from your Voltage regulator. These are the specific wires that should be disconnected as you are testing your exciter.


After disconnecting the red and black wires, proceed to connect these wires to your voltmeter at the right position specified for each.


When you are done with all these, do make sure to ensure continuity between the wires. After checking the continuity between the wires [F+ & F-], it means you have a faulty exciter that should be fixed as soon as possible. This is where a professional electrician comes in to get work done.


For generators to last longer, proper maintenance and regular checks should be a priority. You must understand how a generator works to detect why it doesn't power your whole house.

The most likely reasons for this are a faulty transfer switch and circuit breaker. 

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