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Understanding NFPA 855: A Homeowner’s Guide to Safely Installing Energy Storage Batteries

May 7th, 2024 | Reading Time: 12 minutes

This guide is designed specifically for homeowners with single-family or two-family homes interested in installing energy storage systems. Here, we’ll clearly explain the essential information you need: where you can install your batteries, how many batteries you are allowed per location, and the special safety rules you must follow according to NFPA 855 2020 standards.

Not all states currently enforce NFPA 855 2020. For example, Massachusetts currently enforces NFPA 2020, while Rhode Island enforces NFPA 2018, which does not mention anything about energy storage systems. However, we highly recommend that you follow these standards to protect your family

If your property has three or more living units, this article does not apply to you. You must follow the much stricter rules in the NFPA codebook. 

Battery Locations

Inside Home

If batteries are being installed inside a home, they must be protected by a utility closet, which must have a minimum of 5/8″ gypsum board on the walls and ceiling. Any space inside the home, including the basement, falls under these rules.

You can install a maximum of 40 kWh worth of batteries inside the home

Attached Garages

When installing the batteries inside of an attached garage, the garage must have 5/8″ gypsum board on the walls and ceiling.

It is up to the discretion of the town, but if they feel as though the batteries are subject to vehicle damage, they can require you to install a protection device. The most common protection device is a bollard.

You can install a maximum of 80 kWh worth of batteries inside of a attached garage

Outside of Home – Exterior Walls or Pad Mounted

You can mount batteries directly to the outside of the house, or on a pad. Also, if you have a detached structure on the property that does not have any livable space in it, you can install batteries either on the inside of it or on the outside of it.

You can install a maximum of 80 kWh of batteries on exterior walls of the home, and a maximum of 80 kW of batteries inside of a detached structure.

Fire Detection for Energy Storage

If batteries are installed, either inside the home or in an attached garage, a smoke detector must be installed in the room or closet where the batteries are being installed. The smoke detectors must be interconnected with the rest of the smoke detectors in the house.

What is the maximum amount of energy storage I could have?

You are allowed to have 40 kWh in the utility closet, 80 kWh in a detached garage, 80 kWh in either a detached structure, and 80 kWh mounted on its own pad. This means the theoretical maximum limit you can install on a one or two-family property is 280 kWh.

It is important to note that you can always ask your local fire department for an exception. For example, if you wanted to install a 100 kWh system, they would likely allow you to do this on a pad that is far from the house and also far from anything else that is flammable. However, you would need to seek approval from the fire department to do this.