Defense

EMP and HEMP Protection: Why Critical Facilities Need It

How strong electromagnetic pulses affect electronic systems and how critical facilities are protected.

3 min readAugust 5, 2026Kemar EMC Engineering Team

What Is EMP?

An electromagnetic pulse (EMP) is a very strong electromagnetic field that forms in a very short time. It can cause permanent damage to electronic circuits.

The type that forms at high altitude is called HEMP and can affect a very large area.

How Is Protection Achieved?

The systems to be protected are placed inside a shielded volume. All power, data and ventilation lines entering this volume are fitted with special filters and protectors that stop the pulse.

MIL-STD-188-125 is one of the main references in this field.

Who Needs It?

Command and control centers, critical data centers and energy infrastructure are the facilities that need EMP protection most.

The need and level of protection are determined through a site survey and risk assessment.

Layered Protection and Line Entries

The weakest point of EMP protection is the lines entering the room. Power, data and signal lines are protected in stages with pulse-resistant filters and protectors. Long external lines pass a first stage of protection where they enter the building.

This approach shares the same logic as OT security in critical infrastructure and HIRF and lightning protection in aviation. For our solutions, see the EMP/HEMP protected room page.

Frequently Asked Questions

How is EMP protection tested?

The room's shielding performance is measured and the surge withstand of line protectors is verified to relevant standards.

Does an EMP-protected room also withstand lightning?

Line protectors also protect against lightning surges; the building's lightning protection system is still needed separately.

Can EMP protection be added to an existing data center?

Partial protection can be provided by adding a shielded room or cabinet for critical systems.

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