Just when it seems to be finished business, that old AC versus DC feud has a way of regenerating over and over again. First argued by electricity’s founding fathers, Thomas Edison and Nikola Tesla, the dispute centers around which approach to generating and transporting electricity is safer and more efficient. AC won the early rounds, leading to the grid and building systems we know today. Now, though, a new digital approach to building-wide distribution is forcing some to reconsider their old AC/DC assumptions, especially as DC-powered devices proliferate through homes and businesses. Promising safe operation with low losses and much easier installation requirements, fault-managed power (FMP) could become a new standard for commercial and industrial facilities, with conduit-free installation that’s as easy as running low-voltage cable.

A fault-managed power primer 

Depending on whose equipment you’re looking at, FMP might also be called digital electricity or pulse power. It’s been added to the 2023 edition of the National Electrical Code in the new Article 726 as Class 4, and described by UL Solutions under its new 1400-1 Outline for Fault-Managed Power Systems standard. FMP appears similar in concept to power over ethernet (PoE)—and is often a complement to that approach today. But FMP also offers some significant advantages over PoE’s 20-year-old technology, including: 

Distance: FMP wiring is allowed up to 2 kilometers, or nearly 1.25 miles, versus 100 meters for PoE cabling.

Capacity: FMP can carry up to 450V DC, versus 30V/100W for PoE/Class 2 power systems.

Safety: The limited voltage of PoE systems reduces the danger of shock or fires. FMP designs, though, are safer still, even with much higher carrying capacity. This is because digital controls shut down operations within milliseconds at any sign of a fault. 

However, while FMP’s cable-based installation processes might be similar to what’s used with PoE, FMP is a fundamentally different technology. Power flow isn’t continuous with this approach; instead, grid- or local-supplied power is fed into a transmitter that converts it to 336V DC and breaks that current into packets, just as data is broken into packets in internet-based communications. Every packet (and there are 500 of them sent per second) is checked for safety before being sent over structured Class 4 cable to a receiver that smooths it out and converts it as needed to standard AC or DC current at the desired voltage. Any recognized faults immediately stop transmission. Receivers often are connected to PoE switches, allowing those cables to transmit power to DC-based end-use devices. 

The resemblance to data transmission practices has led FMP’s original patent holder, East Greenwich, R.I.-based VoltServer, to coin the phrase “digital electricity” to describe the process. The company developed the technology to serve cellular communications, particularly 5G radio equipment. These devices have higher power demand than older systems, so would otherwise need AC supply lines and fiber optic data cables. Using FMP, power and data are served by the same cable, which integrators can safely install. As 5G upgrades are spreading throughout airports, hospitals and sports arenas, FMP is becoming a favored option.

“Digital electricity was a natural fit for telecommunication carriers because they could install a transmitter that’s backed up by generators and batteries and use existing communication trays to carry FMP,” said Steve Eaves, VoltServer’s founder and CEO. “They don’t need hard conduit runs that need to be core-bored. These installations are almost $40 a linear foot in hard conduit in a stadium, but it’s about $12 to $15 for digital electricity.” 

This cost advantage has made FMP the new go-to approach for 5G-dense applications such as football stadiums—it’s been used in upgrades to Pittsburgh’s Acrisure and Miami’s Hard Rock stadiums. The new class of data centers and industrial plants now under construction also could be good candidates for FMP, with DC-native servers and other equipment. Eliminating the need for AC-to-DC power conversion at the equipment or device level could add up to significant energy savings, eliminating conversion losses and the resulting heat gain that boosts cooling needs.

Checking into hotel conversions

FMP is also showing up in tech-heavy boutique hotels, such as those converted from former office buildings, to power lighting, window treatments, temperature control and even minibars. In these cases, FMP cables carry power up from basement power servers to floor-level enclosures, where PoE cabling takes over to serve individual DC loads—with no conduit required. This can be especially beneficial in historic renovation projects with limited space to pull new wiring.

“It’s very difficult to upgrade electrical panels in old buildings, because you have to install new feeders,” Eaves said. “Because the digital electricity cable is so thin and flexible, it doesn’t require conduit, and they can sneak it up through tight places in the building.”

This solution was very appealing to Farukh Aslam, CEO of Sinclair Digital, as he built out plans to renovate a Fort Worth office building that was once the headquarters of Sinclair Oil Holdings and has since been rechristened the Sinclair Hotel, under the high-end Marriott Autograph brand. Stringent local historic commission guidelines limited how much installers could disturb original plasterwork, and Aslam also didn’t want to tie hotel systems to proprietary third-party lighting controls to serve native-DC LED fixtures and lamps.

“We have 8,000-plus light fixtures—why would we use AC power to connect to all these lights?” Aslam asked. 

This question led him to explore PoE as a distribution system for lighting (and, eventually, powered window coverings), which, in turn, inspired his interest in FMP as a way to support DC distribution throughout the hotel without raising historic commission concerns.

“We could fish a cable with a camera and see on the iPhone that there was nowhere we could run electrical conduit,” he said. 

Instead, he found lighting suppliers willing to switch out onboard power transformers with ethernet connections for PoE cabling. The installation was completed by system integrators. And the new system, which is easily programmable, supports the high-tech, luxury experience Aslam sought to create. Touch screens are installed at each room’s entrance and in bathrooms, with six preprogrammed light scenes. And, as a particularly high-end feature, bathroom mirrors incorporate small TV screens, all powered by DC carried over PoE cables.

The Sinclair FMP installation was so successful that Aslam started his own consulting company, Sinclair Digital, to assist other developers in their own FMP/PoE efforts. These include the Hotel Marcel in New Haven, Conn., where the firm oversaw design, installation and commissioning of the DC backbone and infrastructure. Aslam said the business is expanding to focus on schools and office buildings.

The Sinclair hotel was renovated, with a distribution plan designed to support digital electricity. All 8,000-plus light fixtures are served by power over ethernet technology, with no conduit required.

FMP as change agent

It’s not hard to see how FMP could lead to big changes in the ways traditional electrical contractors do their work, especially where long wire runs are common. Equipment costs might be too high, for now, for smaller projects. But labor savings could quickly become a decider for many developers, especially as DC-based electronics become the rule in lighting, controls and other equipment.

“Fault-managed power can handle up to 450V and run over a mile, and it’s installed just like ethernet cable,” said Jeff Beavers, NECA’s executive director of network integration and services. “It doesn’t require conduit, and it can be installed by a different classification of worker, so you can see how it’s a disruptor. For a lot of electrical contractors, their core work has been bending conduit and heavy-gauge wire and lighting. Fault-managed power could take the place of all these things.”

Bob Dagostino’s company, Dagostino Electronic Services (DES), Pittsburgh, has been at the forefront of DC power for 50 years, starting with old-school telephony work in the 1970s and ’80s. Since then, it has branched into data networking, building controls, PoE and, most recently, FMP. 

DES has been a lead technology provider to the Pittsburgh Steelers home field, Acrisure (formerly Heinz) Stadium, from its construction. (See “5G Scores in the Steel City” in the June 2024 issue of ELECTRICAL CONTRACTOR for more on this project.) 

DES also recently led the NFL-mandated upgrade to 5G cellular service. The company turned to FMP—and VoltServer—to provide signal and power to 23 new 5G radios.

“Traditionally, we would have needed to source energy from 23 closets,” and still pull fiber optic cable to each radio, Dagostino said, describing how FMP simplified his crew’s efforts. “VoltServer had the ability to reach over 2,000 meters with copper and fiber from a centralized electrical closet, with only a single UPS [uninterruptible power supply] for the closet.”

And, Dagostino added, the data-centric nature of the new technology offers operational benefits to the stadium’s operators, as well. “If we need to power-cycle a device, we can do that from anywhere on the planet. Plus, it’s 100% safe.”

Dagostino sees data centers as the next vertical market to move to FMP, given that servers are DC-native devices. “If you ever look at a single-line diagram for a data center, the traditional method has a lot of moving parts, where digital electricity is very straightforward,” he said, adding that FMP/PoE hybrid designs offer a good solution in these applications. “They’re consuming power as DC, why do all the inversion that we do?”

He also has advice for more traditional contractors who might be eyeing FMP as a threat to their existing business. He suggests starting with reframing their business mission to focus on customer needs, rather than favored technologies.

“Electrical contractors have got to become solutions contractors for delivering electricity safely to an end location,” he said. “DC certainly has a place in the future in meeting the energy needs of their customers.”

sinclair hotel, Quardia Inc. / stock.adobe.com