When I first started meeting with data center operators about their electrical systems, one of the most common questions I heard was also one that made me think: “Can a recloser really work here? I thought those were just for overhead lines in rural areas.” As someone who’s worked in recloser design for over a decade, I get why that assumption sticks—for years, reclosers were seen as utility-side gear, meant to clear temporary faults on long distribution lines before they could cause widespread outages. But today’s data centers are anything but simple rural grids, and our reclosers have evolved to meet their exacting needs. Let me walk you through how we’ve tailored recloser technology for data center electrical systems, and why more operators are adding them to their critical power infrastructure. Recloser
To start, it’s important to recall what a recloser does at its core. Unlike a standard circuit breaker or fuse, a recloser doesn’t just cut power when it detects a fault—it attempts to fix it. It senses an overload or short circuit, trips the line immediately, waits a set amount of time (usually a few seconds), and then tries to reclose to restore power. If the fault is still present—say a bird still sitting on an overhead line or a tree branch still touching a conductor—it trips again, maybe waits a little longer, and tries another time or two before locking out. That ability to “test” a fault is what makes reclosers so useful for overhead distribution, but what does that have to do with data centers, which almost exclusively rely on underground cabling and, for critical loads, redundant, isolated power paths?
The answer starts with how data centers are powered these days. A modern hyperscale data center might connect to two or more utility feeders, each rated for tens of megawatts, from different substations. That’s why they can handle a utility outage on one feeder by switching to the other—right? But that’s only part of the story. Even with redundant feeders, faults happen on the utility side or within the data center’s medium-voltage (MV) distribution network that can trigger unplanned outages, and the speed of response matters more than ever. Data center critical loads—think server racks, storage arrays, cooling systems—can only tolerate milliseconds of downtime before suffering data corruption, hardware damage, or compliance fines. Standard circuit breakers take time to coordinate, especially across multiple power paths, but reclosers operate in cycles, not seconds.
Let’s take a real example from a mid-sized colocation data center I worked with last year. They had two 15kV utility feeders, each feeding a 2000kVA main distribution unit (MDU) inside the facility. One day, a temporary fault on their primary utility feeder—caused by a construction crew accidentally nicking the underground cable insulation—triggered the main circuit breaker in their MDU. The standard breaker took 120ms to trip, and the transfer switch between feeders took 250ms to switch to the backup feeder. Total downtime: 370ms. For the 10 racks hosting a cloud application, that translated to 8 gigabytes of unwritten data in cache being lost, and an estimated $12,000 in immediate fines from their SLA. When they upgraded, we installed a recloser on their incoming utility feeder, set to trip in 30ms, wait 5 seconds, and reclose. The same fault triggered the recloser, which detected it was temporary and restored power in just 10ms. No transfer switch even activated, no downtime, no lost data. That’s the kind of impact reclosers can deliver when sized and programmed for data center environments.
But wait—underground data center infrastructure is different from overhead distribution lines, so how do reclosers adapt here? The reclosers we build for data centers aren’t the same units that hang on utility poles. For underground applications, we’ve designed models with hermetically sealed enclosures, rated for NEMA 4X or higher, to handle dust, moisture, and the occasional harsh conditions in vaults or utility tunnels. We’ve also added advanced fault detection algorithms that can tell the difference between a temporary cable fault, like a nick that burns off, and a permanent fault, like a cut cable or a short between phases. That’s critical because a permanent fault will cause a recloser to trip repeatedly, which is a problem—you don’t want a recloser cycling on a dead feeder for minutes when the actual issue is a broken underground cable that needs repair. Our reclosers use a combination of current waveform analysis, harmonic detection, and event logging to distinguish between fault types, which is something we refined specifically for industrial and commercial electrical systems, not just rural overhead lines.
Another key advantage of reclosers in data centers is their ability to simplify coordination across the entire electrical network. Data center electrical systems use tiered protection: incoming utility feeders, main breakers, sub-main breakers, and then branch breakers feeding individual rack rows. The challenge with tiered protection is “selectivity”—making sure only the breaker closest to the fault trips, not a breaker upstream that would take more critical loads offline. Coordinating standard breakers across MV networks can take weeks of testing and calculation, especially when there are multiple feeders and redundant paths. Reclosers, though, have adjustable trip curves and reclosing timings that we can set to work seamlessly with the rest of the data center’s protection gear. For example, if a branch breaker detects a fault, it can send a signal to the upstream recloser to block a reclosing attempt, so the recloser doesn’t try to power a faulty circuit that could damage equipment or trigger a larger outage. That level of coordination reduces fault-related outages and makes maintenance easier, because the protection system is more predictable.
I know what some operators are still thinking: “What about siting? We don’t have space for extra gear in our data center vaults.” Fair point, but reclosers for data centers are compact—many models are just a few feet tall, designed to mount alongside standard MV breakers in existing vaults or utility closets. We also offer rack-mountable options for smaller edge data centers or colocation facilities that don’t have large dedicated vaults. One edge data center in the Midwest had space for a single MV cabinet next to their utility transformer, so we installed a recloser in the cabinet that also housed their incoming breaker and surge protection. It fit without modifying their existing infrastructure, and when a temporary fault on the overhead utility feeder (yes, even edge data centers sometimes have overhead feeders) triggered, the recloser cleared it before it could reach their transformer and servers.
Of course, reclosers aren’t a one-size-fits-all solution. They work best for incoming utility feeders, whether overhead or underground, and for primary distribution points in MV data center networks. They’re not meant to replace branch breakers for individual rack loads, which need more granular protection to prevent a single server fault from taking out a whole row. They also require regular maintenance, like any electrical gear—inspecting contacts, testing trip functions, updating firmware on the control module. But that maintenance is minimal compared to the downtime they prevent, especially for data centers with strict SLAs.
I’ve seen this play out across different types of data centers, too. Hyperscale data centers, with their hundreds of MW of load, use reclosers on each of their utility feeders to avoid the cost of SLA fines and data loss. Colocation providers, who rely on their ability to guarantee uptime for multiple tenants, use reclosers to offer a higher tier of power service to customers who need near-perfect reliability. Even edge data centers, which are often located in remote or underserved areas with less reliable utility power, use reclosers to stay online during the frequent temporary faults that come with overhead lines.
Let’s go back to that first question I get: “Can a recloser be used in a data center electrical system?” The short answer is yes, but not the same recloser you’d find on a rural utility pole. At our company, we’ve spent years adapting recloser technology to meet the unique needs of data centers: faster trip times, advanced fault detection for underground cables, compact design for limited space, and seamless coordination with existing protection systems. We work with data center engineers and operators to site reclosers in the right places, program them to match their specific network, and provide ongoing support to make sure they operate as intended.
If you’re evaluating ways to reduce unplanned downtime in your data center’s electrical system, adding a recloser to your incoming feeders or primary distribution points is worth considering. It’s not a new or untested technology—reclosers have been used in critical power systems for decades—but it is a technology that’s been refined for the modern demands of data centers. We’ve helped dozens of facilities implement reclosers and see measurable reductions in fault-related outages, lower SLA fines, and more reliable power for their loads.
If you’re ready to discuss whether a recloser makes sense for your data center’s electrical system, we’d welcome the chance to work with you. We can conduct an assessment of your current power infrastructure, suggest the right recloser model and placement, and walk through how it would integrate with your existing setup.
Sensor References
- Electric Power Research Institute (EPRI). "Recloser Coordination for Industrial and Commercial Systems," 2021.
- International Electrotechnical Commission (IEC). "Switchgear and Controlgear for Medium Voltage," IEC 62271, 2022.
- Uptime Institute. "Tier Standards for Data Center Design, Construction, and Operational Sustainability," 4th Edition, 2020.
- National Fire Protection Association (NFPA). "Standard for Electrical Safety in the Workplace," NFPA 70E, 2021.
Henan Yihe Electric Apparatus Co., Ltd.
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