EMP Protection: How to Protect Electronics and Prepare
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EMP protection focuses on reducing the risk that an electromagnetic pulse could damage equipment your household relies on. While large EMP events are rare, they could damage electronic devices, the electrical grid, and other critical infrastructure.
Electromagnetic pulses can come from powerful solar storms or from a high altitude nuclear explosion. In either case, the main concern is the sudden burst of energy that can travel through power lines and electronic systems.
Fortunately, there are practical steps you can take to protect important equipment and prepare for disruptions. In this guide we’ll cover simple EMP protection strategies, including shielding electronics, reducing vulnerability to electrical surges, and building household resilience.
If you want to understand what happens during an EMP event, see our companion guide: “What Happens if an EMP Hits? How It Impacts Daily Life.”
Table of Contents
What an EMP Is Most Likely to Damage
Electromagnetic pulses primarily affect electronics connected to long conductors such as wiring and power lines. When a large electromagnetic pulse EMP interacts with these systems, it can send damaging voltage surges through electrical circuits.
The most vulnerable equipment includes:
- devices plugged into the electrical grid
- equipment connected to long antenna wires
- sensitive electronic systems
- communication equipment
- grid infrastructure such as transformers
Large infrastructure components are difficult to replace, which is why grid damage is often the biggest concern.
Electronics Most Vulnerable to EMP
Many modern devices contain delicate microelectronics that could be affected by a strong electromagnetic disturbance.
Examples include:
- computers and laptops
- smartphones and tablets
- televisions and radios
- internet routers and modems
- solar power inverters
- generators and battery chargers
- satellite communication equipment
These devices can sometimes be physically damaged if a large electrical surge reaches their circuitry.
Electronics Most Likely to Survive
Not all electronics will automatically fail during an EMP event.
Devices that may be less vulnerable include:
- small battery powered electronics
- equipment not connected to wiring or antennas
- devices stored inside shielding containers
- simple electronics with minimal circuitry
Mechanical tools and non-electric equipment are unaffected by electromagnetic pulses. For this reason, many preparedness plans include both modern electronics and low-tech backups.
EMP Protection Using Faraday Cages
One of the most commonly discussed EMP protection methods is a Faraday cage. A Faraday cage is a conductive enclosure that blocks or redirects electromagnetic energy around the outside of the container instead of allowing it to reach the electronics inside.
When a strong burst of electromagnetic energy occurs, the metal shell of the cage spreads the electrical charge around its surface. This prevents the energy from reaching the electronic devices stored inside.
Because the charge stays on the outside of the conductor, the interior remains protected. This effect works whether or not the cage is connected to ground.
Faraday cages are often used as a practical EMP protection strategy for small electronics such as:
- battery powered radios
- emergency communication devices
- spare solar power electronics
- backup computers or hard drives
The key idea behind EMP protection it to keep energy from reaching the circuits.
For small Faraday cages used to protect electronics:
- grounding usually does not improve protection
- improper grounding can actually introduce a path for energy into the container
Simple EMP Protection Options for Small Electronics
There are several ways to create basic shielding for important devices.
Metal Container Faraday Cage
A common home solution is a metal container such as:
- a steel trash can
- a metal ammunition box
- a metal filing cabinet
To improve protection, insulate devices inside it from direct contact with the metal container using cardboard, wood, or cloth.
Aluminum Foil Shielding
Small devices can be wrapped in layers of aluminum foil to create a basic shield.
For best results:
- wrap the device in insulating material first
- completely cover it with foil
- avoid gaps in the shielding
This approach can provide a simple form of electromagnetic shielding for small electronics.
EMP Protection Bags
Commercial EMP protection bags are designed with conductive layers that act like portable Faraday cages.
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These bags are often used for:
- handheld radios
- emergency communication equipment
- small backup electronics
Grounded Metal Structures
Some buildings with properly grounded metal roofs or siding may provide partial shielding from electromagnetic disturbances. However, protection varies depending on wiring, grounding, and construction.
Because many devices are connected to household wiring or power lines, shielding individual electronics is usually more reliable than relying on building structure alone.
How an EMP Might Affect Vehicles
Cars and trucks may be more resilient than many other electronic devices. The metal body of a vehicle acts as a partial Faraday cage. This can help shield some of the electronics inside from external electrical energy.
You may have heard the safety advice that if a power line falls on your car, you should stay inside the vehicle. This works because the metal body of the car directs electrical current around the outside of the vehicle.
If you get out of the vehicle, your body could become part of the electrical path to the ground. This is why emergency responders advise staying inside until the line is de-energized. This same “Faraday cage” effect may offer some protection during smaller EMP events.
Older vehicles generally have simpler electrical systems, which may make them somewhat less vulnerable than modern vehicles. However, all vehicles still contain wiring and sensitive electronics that could potentially be affected.
Vehicles include several components that could pick up electromagnetic energy, including:
- the 12-volt electrical system
- radio antennas
- wiring harnesses
- engine control modules and sensors
Because of these connections, a strong electromagnetic pulse could still damage vehicle electronics.
Some studies suggest that vehicle electronics might survive weaker pulses (around 0.25 kV/m), particularly if the vehicle is not running. As the strength of the pulse increases, however, the likelihood of damage to electronic systems increases as well.
In short, some vehicles may continue operating after an EMP event. Others could experience temporary or permanent electronic problems.
Preparing for Power Grid Disruptions
For most households, preparing for an EMP event looks very similar to preparing for a long power outage. This is because the biggest impact of an EMP is likely damage to the electrical grid.
Helpful preparations include:
- emergency lighting
- alternative cooking methods
- stored food and water
- battery powered radios
- backup heating or cooling options
We recommend storing at least 72 hours of supplies, though longer is better. Our electric grid is old, and electric demand keeps climbing. In many areas, it’s not “if” there will be power outages, but “when”.
Protecting Solar Power Systems
Many homesteads rely on solar power systems for backup electricity. These systems contain sensitive electronics such as:
- charge controllers
- inverters
- battery management systems
Because these components are connected to wiring and solar panels, they could be vulnerable during large EMP events. You would need to store spare electronic components in a protective enclosure or Faraday cage so replacements are available.
EMP Shield Devices
Some companies sell EMP shield devices designed to protect electrical systems from large electrical surges. These devices are usually installed on a home’s electrical panel or connected to equipment.
Most EMP shield devices work in a similar way to advanced surge protectors. They are designed to divert or absorb voltage spikes that travel through wired connections.
Do these EMP Shield devices work? Not completely.
A large EMP can reach electronics through several pathways, not just through household wiring. For that reason, consider EMP shield devices as one layer of protection, not a complete solution.
It’s best to combine surge protection, a Faraday cage, and preparing for possible power outages.
Protection from a Large EMP
A widescale, powerful EMP is far less likely. If it did happen, it would be chaotic. The military would likely be called in to maintain order, but would be stretched beyond its capacity.
We’ve all seen how quickly grocery stores empty during emergencies. A large electromagnetic pulse would be worse. You would need to be prepared to live without power for a few months to a year or more.
Basically, you would need to prepare to live an 1800s lifestyle – wood stove, hand-tools and no electrical power. You would need tools and equipment necessary to garden, hunt, prepare food without electricity or gasoline. You would need a good stock of books, tools, medicine, and learn a LOT of skills.
If you want power, you would need to a full electrical power generation system (protected from the EMP) and spare parts. You won’t be able to get gasoline or natural gas, so generators won’t last long.
EMP Protection = Energy Awareness
An EMP—no matter the source—has the potential to disrupt electronic systems and damage the electrical grid. Shielding electronics can reduce risk, but the most effective protection is being able to function during extended power outages. See What to Do When the Power Goes Out (10 Things to Prepare).
Could you get through your daily activities without power, and for how long? If you had to choose small electronic items to protect, what would they be? Inexpensive Faraday bags help protect small items, and EMP shield products offer some protection for larger systems. As always, it’s about being able to work with what you have to make the best of a situation.
Widescale EMP impact is low, but it’s only one of many reasons for power grid failure.
This article is written by Laurie Neverman. She lives in northeast Wisconsin with her husband and sons. They grow and preserve most of their food on their homestead, and have a root cellar, greenhouses, and canning pantry. Her book, Common Sense Preparedness, will help you become more resilient without the hype.