An arc flash is a sudden and explosive release of energy caused by an electrical fault, otherwise known as a fault current. Arc flash can cause severe injuries, equipment damage, and even catastrophic downtime. A data center outage can have a devastating impact due to business disruption, lost revenue, and reduced productivity.
Arc flash risks can be safely mitigated by putting the correct procedures in place. In this article, we’ll explore some specific arc flash risks you may encounter in data centers. Keep reading to explore the causes of these dangers and how to keep fault current and arc flash risks to a minimum.
Typical electrical power distribution systems in data centers
Before we dive into arc flash risks that may exist within your data center, let’s take a moment to understand the electrical power infrastructure.
By understanding the power distribution within your data center, you’ll have a better idea of how to effectively manage arc flash risks — and mitigate them before anything bad happens.
Generally, data centers will use one of two common electrical power infrastructures: legacy systems and electrical busway systems. Each of these systems presents unique arc flash risks that require careful attention.
Legacy systems
Legacy systems refer to data center infrastructure that follows the more traditional methods of wiring and circuit configuration. These systems can be prone to fault current due to aging equipment, complex configurations, and outdated technology.
In these types of systems, power is typically routed from an Uninterruptible Power Supply (UPS) or a Power Distribution Unit (PDU) into a Remote Power Panel (RPP) made up of circuit breakers. From the RPP, individual panels feed into smaller PDUs in the server rack. While this hierarchical approach to power distribution is reliable, it can be complex. As a result, it requires careful management by trained professionals to prevent faults and mitigate arc flash risks.
Electrical busway system
Electrical busway systems offer a more modern approach to power distribution for data centers. These systems operate by suspending electrical busways from the ceiling above rows of server cabinets. The busways facilitate the flow of power between an RPP and rack-level PDUs.
This streamlined and flexible setup simplifies the power distribution and makes it easier to adjust or expand the data center equipment. Having the equipment suspended from the ceiling can offer some electrical safety advantages. However, there are still arc flash risks associated with electrical busway systems that you should be aware of when managing data center electrical equipment.
Arc flash risks associated with modern electrical systems in data centers
Modern electrical systems like electrical busways can offer greater electrical safety advantages over legacy systems, thanks to their streamlined design and enhanced flexibility. However, they are not entirely without fault or risk.
There are still arc flash risks associated with electrical busway systems that you should be aware of when managing data center electrical equipment.
Higher efficiency design
Electrical busway systems are designed to improve power efficiency. In turn, this significantly reduces power losses from UPSs and transformers.
To keep power losses to a minimum, data center designers often opt for fewer and larger transformers. While this approach enhances efficiency, it also increases the amount of available fault current present in IT racks. This heightened potential for fault current poses a greater risk of arc flash incidents. As such, vigilant safety measures must be put in place to mitigate potential hazards.
Increased rack densities
Rack densities in modern data centers have surged to around 6-12 kW per rack, with some data center operators looking to support over 40 kW per rack. This is exponentially larger than we’ve experienced in the past.
With greater rack density comes a need for increased current circuit ratings and larger wires. These increased wire sizes and current circuit can lead to a rack fault current that can be 10 times higher than that found in legacy data centers.
Such a dramatic increase in fault current heightens the risk of arc flash incidents, meaning data center managers must adopt robust safety protocols and use the appropriate arc flash safety clothing and PPE.
Higher data center capacities
High-density data centers are designed to pack more computing power into a smaller footprint, strategically increasing capacity.
Modern data centers are often built to support an IT load exceeding 1,000 kW. Meanwhile, large hyper-scale data centers can require tens to hundreds of megawatts of power.
With how much our society relies on digital technologies, it’s not surprising that data centers need to up their capacity levels.
But, this increased capacity also leads to a greater risk of higher available fault currents. Higher data center capacities mean the utility connections provide a fault current of more than 50 kA on the medium voltage transformer’s low voltage side.
In contrast, a data center with a 500 kW capacity would experience half the amount of fault current. As data centers transition toward higher capacities, the overall fault current also increases significantly. This escalation highlights the importance of developing robust safety measures to manage the increased risk of arc flash incidents.
Arc flash risks of data center equipment
Data centers rely on substantial amounts of energy to keep running continuously, making their electrical infrastructure critical to their day-to-day functioning.
Understanding the arc flash risks associated with each layer of electrical equipment — such as RPPs, panelboards, and rack power strips — is essential for ensuring the electrical safety and reliability of your data center.
Remote power panels (RPPs)
RPPs play a key role in distributing power within data centers. The live components within an RPP pose an arc flash risk. Causes of arc flash in RPPs may be due to poor electrical contact, aged components, insulation failure, or inadequate maintenance.
Arc flash risks with RPPS are particularly high during maintenance activities. If a circuit breaker needs replacing in the RPP, the maintenance work is typically performed live with exposed power conductors. This practice increases the risk of a worker touching a live circuit or creating an arc between connectors.
Panelboards and switchboards
Panelboards and switchboards handle large volumes of electrical energy. As such, they present arc flash risks that need to be managed.
Panelboards are typically mounted on steel bracings, or balls, and are accessible from the front. This makes them similar in design to RPPs but, unlike RPPs, they have dead fronts meaning there are no live parts exposed to the person operating the equipment.
Switchboards are similar to panelboards, except they are typically floor mounted and deeper than panelboards. As per the NEC, a switchboard is a large, freestanding assembly of electrical equipment with a common enclosure, including switchgear, panelboards, and other types of distribution equipment.
Whereas panelboards are generally rated for up to 600V and can handle fault currents of 10kA to 65kA, switchboards are designed to handle higher fault currents. Switchboards can typically handle fault currents up to 5kA, depending on the design and devices used.
The high fault current of panelboards and switchboards can increase the risk of arc flash incidents. So, these systems should only be handled by trained personnel with the correct arc flash PPE.
Electrical busway systems
Electrical busway systems, used in place of panelboards for distributing power, run above IT racks in sets of four or five busbars.
Their ceiling-mounted design offers an appropriate distance from the limited approach boundary (LAB), allowing people to approach the busway area with a reduced risk of electric shock from fault currents. It’s worth noting that the arc flash boundary is at a greater distance than the LAB. Improper design or installation could cause electric shocks and arc flash incidents.
The placement of electrical busway systems also means there is a high available fault current in close proximity to the IT rack. This close proximity can increase the risk of arc flash incidents if there is a fault, due to a high density of energized components in the space.
Maintenance work should be conducted when the plug-in units are uninstalled from the busway to minimize the likelihood of arc flash events.
Power distribution units (PDUs)
PDUs are a vital component in data centers, containing an isolation transformer and multiple panelboards. The isolation transformer processes the same amount of voltage for both input and output, acting as a source of impedance for fault current. However, it does not eliminate the risk entirely.
The high power density associated with PDUs can increase the risk of arc flash incidents. In the event of a fault, closing a circuit breaker could trigger an arc flash event. This potential hazard underscores the importance of following appropriate safety protocols and using arc flash protective equipment when working with or maintaining PDUs.
UPSs (uninterruptible power supplies)
UPS systems are considered an essential piece of equipment in data centers as they provide immediate backup power in case of a power outage. Because of this, they also safeguard electrical systems from power disturbances and help prevent downtime.
UPSs are designed to increase efficiency, causing them to handle large amounts of electrical energy. This increases their susceptibility to arc flash hazards, which can be extremely dangerous compared to lower-voltage equipment.
UPS systems are designed to ensure continuous power within the data center. Even when the unit itself is turned off, UPS systems may still receive power from another source. As such, arc flash risks are particularly high when engineers need to perform maintenance work on UPS systems, especially if they need to work on live equipment.
The constant power flow associated with UPSs requires careful operation and maintenance.
It is critical that only trained professionals wearing suitable arc flash safety clothing and PPE maintain RPPs. Follow strict maintenance procedures, implement appropriate engineering controls, and regularly inspect RPPs to prevent insulation failures or other issues that could cause arc flash.
Rack power strips
Rack power strips, also known as rack PDUs, typically handle far lower fault currents than larger electrical distribution equipment like switchboards or UPS systems.
Rack power strips, fed by small gauge wires, are often the final components in the power distribution chain within data centers. As a result, the available fault current at this stage is at its lowest. The fault current in a 20-amp circuit, which is common for rack PDUs, is typically lower but still significant enough to pose a risk of arc flash incidents.
To ensure arc flash risks are minimized, workers should ensure the strips are turned off before unplugging or plugging input connectors of rack power strips into the supply connector.
The lower fault current and controlled handling makes rack power strips relatively safe to manage, reducing the risk of arc flash events with this particular component.
Other arc flash risk considerations
The equipment and systems in your data center certainly play an important role in electrical safety. However, they aren’t the only consideration when it comes to managing arc flash risks.
Data centers operate 24/7, demanding round-the-clock data processing and storage. As such, there are many more factors that run the risk of causing arc flash incidents within data centers. Hazards associated with human error, environmental conditions, complex systems, and equipment maintenance and failure all need to be kept in mind when operating or working within data centers.
Human error
All it takes is one small, innocent mistake to cause catastrophic damage. Human error is a major player when it comes to arc flash risks in data centers. That’s why it’s important that all data center employees are well trained and suited up with the correct PPE when handling or near electrical equipment.
Ensuring everyone knows their stuff and follows safety procedures is key to minimizing arc flash incidents.
Environmental conditions
When it comes to the electrical safety of your data center, you can’t overlook environmental conditions. Overheating, poor ventilation, and dust accumulation all create a perfect storm for potential arc flash risks.
With so much equipment running at once, and not to mention constantly, data centers can quickly become hot environments. Cooling solutions are often employed to help maintain the right temperature within data centers. High temperatures can degrade electrical components, cause thermal stress, and increase the risk of arc flash, so maintaining appropriate temperature levels is crucial.
While cooling solutions can be helpful, they also pose arc flash risks due to adding another layer of electrical energy into the system.
Poor ventilation and dust accumulation can both cause heat build up around electrical equipment, exacerbating issues with overheating. Dust also runs the risk of creating paths for electrical currents to arc across, potentially triggering an arc flash event.
Keeping your data center environment clean and controlled is critical to reducing risks and maintaining a safe working space.
Complex systems
By now, you’re likely well aware that data centers are complex. With multiple power sources, components, and systems designed to ensure uninterrupted operation, there are many layers of arc flash risk.
Managing the intricate setup of data center infrastructure requires constant vigilance and keen electrical safety expertise to minimize arc flash risks. Proper planning, training, and maintenance will all help your data center workers navigate these complexities safely.
Equipment maintenance and failure
We’ve spoken a lot about the arc flash risks associated with various types of electrical equipment within data centers. Across all equipment, improper maintenance or component failure can be a significant contributing factor to arc flash risks.
These arc flash risks can be reduced by ensuring equipment is regularly inspected and any issues are addressed promptly. Performing an arc flash analysis will also help you identify any high risk areas within your data center.
Reducing arc flash risks in data centers
Arc flash risks in data centers are multifaceted. From the electrical systems themselves to external factors like human error or environmental conditions, there are many layers involved in data center electrical safety.
Even the most professional and well-managed data centers are not immune to arc flash incidents, highlighting the importance of ensuring rigorous safety procedures, training, and arc safety protective equipment are all in place.
Download our Electrical Safety Issues in Data Centers eBook to learn more about ensuring your data center operates safely and efficiently. This guide offers in-depth guidance and expertise to help you navigate data center electrical safety, and mitigate any risks associated with arc flash events.
