Generator safety
How to prevent backfeed and protect your home and lineworkers
Using a backup generator during an outage can bring peace of mind, but it can also create serious danger if it causes backfeed. Backfeeding happens when electricity flows in the wrong direction and unexpectedly energizes power lines during an outage. That can put Middle Tennessee Electric lineworkers at risk of electrocution and can also damage equipment on the grid or in your home. Tennessee law also requires safety devices that prevent unintentional power flow from electric generating equipment connected to the power grid.
Understanding the dangers of backfeed
Backfeeding occurs when electricity flows in the opposite direction from its intended path. During a power outage, that uncontrolled flow can energize lines that lineworkers expect to be de-energized while they are making repairs. It can also damage equipment on the grid or inside your home.
Why generator safety matters
When storms cause outages and send crews into the field, one of the most serious risks can come from behind-the-grid power generation that is not installed or operated correctly. Members who use a generator or another backup power source have a responsibility to make sure it is set up to prevent backfeed.
Generator safety tips
For your safety and the safety of our lineworkers, it's important to use generators safely during extended outages. Here a few tips to keep you and lineworkers safe:
- Never plug a generator into a wall outlet. Always use a properly installed transfer switch to avoid creating dangerous backfeed.
- Never use them indoors. Keep generators at least 20 ft. away from your home and away from doors, windows and vents.
- Use outdoor, heavy-duty extension cords and always have carbon monoxide detectors in your home.
- Let the generator cool for at least 20 minutes before refueling.
Watch the generator safety video
This video gives members a quick overview of generator safety and the risks of backfeed before using backup power during an outage.
The safest next step
Proper installation by a professional electrician and regular service helps protect your home, your property, and the lineworkers restoring power. If you use a generator or another backup power source, make sure it has the right safeguards in place before the next outage.
Generator safety FAQs
What is backfeed?
Backfeed happens when electricity flows in the wrong direction from a generator or another power source and energizes lines or systems it is not supposed to reach.
Why is backfeed dangerous?
If power lines become unexpectedly energized during an outage, lineworkers making repairs could be electrocuted. Backfeed can also damage equipment on the grid or in your home.
Can a portable generator cause backfeed?
Yes. Plugging a portable generator directly into a wall outlet or your home’s electrical system can send electricity through your home and back onto power lines.
Can a permanently installed generator cause backfeed?
Yes. A permanently installed generator can also cause backfeed if it is not installed or used correctly.
What safety equipment is required for a generator?
All generators must have an automatic or manual transfer switch to safely disconnect them from the grid.
Can solar systems cause backfeed too?
Yes. Improper or unauthorized solar installation can also cause backfeeding. Solar systems should be professionally installed and use inverters that detach the house service from the Middle Tennessee Electric line during an outage. The inverter’s anti-islanding feature should be enabled and working correctly.
Can battery-stored power or electric vehicle batteries cause backfeed?
Yes. Battery-stored power can also create a backfeeding risk if it is not set up correctly. A bidirectional charger must be properly installed, and a transfer switch is required.
What is the safest way to set up backup power?
Backup power systems should be installed and regularly serviced by a certified electrician who understands how to prevent backfeed. This is not a do-it-yourself project.