Generator Running But No Power to the House
Here’s What to Check
The power goes out. Your standby generator starts just like it's supposed to.
But there's a problem—the generator is running, and your house is still without power.
What's going on?
One of the most common misconceptions about a standby generator is that if the generator starts, the house should automatically have power. That isn't necessarily the case.
A generator running does not mean the generator is supplying power to the home.
There are several steps between the generator starting and generator power reaching your electrical panel. When I encounter this problem in the field, the cause is usually one of two things:
- The generator's output breaker is OFF.
- There is a problem with the automatic transfer switch.
Check the Generator Breaker
This is the first thing I check—and surprisingly often, it's the problem.
The generator's output breaker is normally located inside the generator enclosure. If it's OFF, the generator can start and run perfectly while supplying zero power to the house.
Why would it be OFF?
Usually, someone turned it off.
It may have been left off after routine maintenance, electrical work, troubleshooting, or previous service.
Generator breakers generally don't just turn themselves off. If you find the breaker OFF, turn it ON only if you know it was intentionally switched off and there is no indication of an electrical problem.
If the breaker has actually tripped, or trips again when reset, don't keep resetting it. There may be an electrical fault that needs to be diagnosed.
If the Breaker Is ON, Check the Transfer Switch
If the generator is running normally and the generator breaker is ON, the next suspect is the automatic transfer switch (ATS).
The transfer switch is responsible for disconnecting the home from utility power and connecting it to generator power when the utility fails.
If the switch doesn't transfer, the generator can run perfectly while your house remains without power.
Transfer switch problems generally fall into two categories:
- Electrical: A failed control component, relay, fuse, sensing circuit, wiring problem, or other electrical issue can prevent the switch from transferring.
- Mechanical: The physical transfer mechanism can fail to move, bind, or otherwise prevent the contacts from switching from utility to generator power.
In either case, the generator itself may be doing exactly what it's supposed to do.
What About the Yellow Handle?
If you have a Generac automatic transfer switch, you may have noticed the small yellow manual transfer handle supplied with the switch.
This handle allows a qualified technician to manually move the transfer mechanism from one power source to the other when performing certain service or testing procedures.
But there is a very important safety warning:
The yellow handle should NEVER be used to transfer the load from one live source to another.
If either the utility or generator source is energized, manually moving the transfer mechanism can create a dangerous arc, resulting in serious injury, equipment damage, or both.
The manual handle is a useful tool for a qualified technician when the proper safety procedures have been followed, and the appropriate power sources have been de-energized.
For homeowners, the safest approach is to observe the transfer switch's position or indicator, if provided, and leave manual operation of the switch to a qualified technician.
What Can You Check? As a homeowner, there are a few things you can safely observe:
- Is the generator actually running?
- Does the generator display show a fault or warning?
- Is the generator's output breaker ON?
- Does the transfer switch appear to have transferred, if your particular switch provides a visible indication?
Don't remove covers or reach inside the generator or transfer switch. These systems contain potentially lethal voltages.
If the generator is running, the breaker is ON, and the home still doesn't have power, it's time for proper electrical troubleshooting.
A qualified technician can determine whether the generator is producing the correct voltage, whether that voltage is reaching the transfer switch, and whether the transfer switch is actually connecting generator power to the home.
The Bottom Line:
If your generator starts when the utility power fails but your house remains without power, don't automatically assume the generator has failed.
- Start with the simple things.
- Check the generator breaker.
- If it's ON, the transfer switch is the next place to look.
In my experience, a generator breaker that was left OFF or a problem with the transfer switch accounts for a large percentage of these calls.
Remember:
- Generator running ≠ generator powering the house.
- The generator has to produce power, and the transfer switch has to deliver that power to your home.
- Sometimes the solution is as simple as turning the breaker back on.
- And sometimes, that's where the real troubleshooting begins.
