The Two Seconds You Design For: Making the Case for Arc-Resistant Switchgear

Picture the person who runs your facility. On a normal Tuesday, a technician is standing at the medium-voltage switchgear in the electrical room, doing a routine operation.

Somewhere inside that lineup—a loose connection, a failed insulator, a tool left where it shouldn't be—a fault ignites.

What happens next takes less than two seconds.

An internal arcing fault releases an enormous amount of energy almost instantly. The air inside the enclosure superheats to temperatures several times hotter than the surface of the sun. Copper vaporizes and expands violently. The result is a pressure wave, a fireball, and shrapnel—directed, in standard equipment, wherever the blast finds a way out.

Often that's straight through the front doors, toward whoever is standing there.

For the facility manager, that scenario is two problems at once, and they're inseparable. The first is the person in front of the gear. The second is everything behind it: the equipment, the process it powers, and how long the operation is down. Arc-resistant switchgear is engineered to answer both.

What "Arc-Resistant" Actually Means

It's a common misconception that all switchgear is built to handle a fault. Standard switchgear is designed to interrupt fault current—it clears the electrical problem. What it is not designed to do is contain the explosion that a serious internal arc produces. That's a different problem, and it's the one that hurts people and destroys rooms.

Arc-resistant switchgear is built for the failure, not just the function. Rather than trying to prevent the blast from escaping, it gives the energy a controlled path out. When an internal arc occurs, the superheated gases are channeled upward into a plenum—a dedicated duct system—that vents them away from the front, sides, and rear of the equipment and carries them to a safe area, typically outside the building. The person standing at the gear is shielded from the worst of it. The blast goes up and out, not into

the room.

This isn't a marketing claim. Arc-resistant designs are tested and rated to IEEE C37.20.7, a standard that involves staging a real internal arc fault against the enclosure and verifying that it protects personnel as promised.

How Much Protection, and Where

Not all arc-resistant gear offers the same coverage, and this is where a facility manager's specification decision gets real. IEEE C37.20.7 defines accessibility types:

•     Type 1 provides protection at the front of the equipment.

•     Type 2 extends that protection to the front, sides, and rear—important when personnel can walk around or behind the lineup.

•     Type 2B adds protection when low-voltage instrument compartments are open.

•     Type 2C goes further still, isolating compartments from one another so that a fault in one section doesn't cascade into the next.

That last point is where safety and uptime meet. A Type 2C design doesn't just protect the people in the room—it can keep a fault contained to a single compartment, so the rest of your equipment survives and the path back to operation is shorter. In a market where replacement medium-voltage gear can take a year or more to arrive, "the fault didn't destroy the whole lineup" is not a small thing.

When It's Worth the Premium

Arc-resistant switchgear costs more than standard gear, and it isn't required everywhere. The question a facility manager has to answer is where the exposure justifies it. The strongest cases share a few traits: electrical rooms that are regularly occupied, operations where downtime is measured in dollars per minute, and any situation where work happens on or near energized equipment. Hospitals, water treatment plants, data-adjacent facilities, and continuous-process industrial sites tend to check every box.

The decision also shouldn't be made blind. An arc flash study quantifies the incident energy actually present at each piece of equipment—turning "this feels dangerous" into a number you can design around. Paired together, the study tells you the size of the risk and the arc-resistant gear tells you how you're going to manage it.

The Bottom Line

The whole point of arc-resistant switchgear is a moment you hope never comes. But designing for those two seconds is what protects the technician standing at the gear and the operation depending on it—at the same time. For the facility manager weighing the spec, that's the balance worth paying for: people go home safe, and the business keeps running.

Tech Electric supplies and helps specify arc-resistant switchgear, and our engineering department performs the arc flash studies that quantify your risk in the first place. Want help deciding where arc-resistant gear makes sense for your facility? Request a quote at techelectric.com/request-a-quote or call us at 262-783-2222.