April 24, 2023
Most people know that LED lighting is more efficient than other lighting options. Some governments have even placed bans on the sale of other types of lighting, such as fluorescent and incandescent. This will ultimately push more businesses to adopt LED lighting throughout their facilities. LEDs being more efficient, among other benefits, is why the global LED lighting market size is anticipated to reach USD 168.87 billion by 2030, and is expected to expand at a CAGR of 11.0% from 2023 to 2030. And with the rising popularity of LED lighting, comes the rising popularity of low-voltage power distribution systems. You might not have known this, but all LED’s (light emitting diodes) are low-voltage DC (direct current) devices, even if we often plug LED fixtures into AC (alternating current) line voltage power sources.
This article will cover the benefits of low-voltage LED lighting, and options to power it efficiently.
LEDs (Light Emitting Diodes) essentially convert electrical energy into light energy with semiconductors. When comparing LED lighting options, you’ll come across line-voltage and low-voltage LED light fixtures. Line voltage fixtures typically require 120V - 240V, while low-voltage LED fixtures typically require a constant voltage (CV) or constant current (CC) power source. Constant voltage power sources are typically direct current (DC), and usually come in either 12, 24, 36, or 48 volt DC outputs. Constant current power sources come in a variety of current levels, and are usually custom made for the LED fixture they are powering. In both cases, low-voltage lighting systems are typically limited to 100 watts (or Volt Amps), in order to comply with Class 2 power limits. Low-voltage lighting can be employed in situations where running standard line voltage (or AC) lighting systems would be overkill. This is typically the case in LED lighting installations where the distance between the power supply and the light fixture is short enough that voltage drop won’t be a problem.
Low-voltage LED lighting systems are usually Class 2 low-voltage, and don’t require mechanically protected cable, or conduit. One of the main reasons why someone might go with line-voltage (AC) LED lighting over low-voltage LED lighting is that the latter has distance limitations. To explain further, if a lighting project requires cables to be significantly long, supplying low voltages along cables can result in voltage drop (line losses). On the other hand, there are many benefits to using low voltage systems for LED lighting when possible. Among other benefits, it’s safer than line voltage, less permanent, and more energy efficient than line-powered fixtures. There is also a new type of power distribution system that combines the benefits of line voltage and low-voltage systems, called a Class 4 power system, and we’ll touch on that at the end of this article. When used together, a Class 4 high-voltage and Class 2 low-voltage system can be the ideal option in power distribution for LED lighting.
Because LEDs use semiconductors, they require low-voltage DC (direct current) power to operate, and cannot be powered directly by AC (alternating current) power like an incandescent bulb can. The problem is, power grids supply AC power to homes and businesses, so LED manufacturers must take this into consideration; that’s where LED drivers come in. In low-voltage LED lighting systems, remote drivers are typically used and are located separately from fixtures. LED fixtures powered by line voltage typically use integrated drivers, meaning voltage regulation is built-in to the fixture. The purpose of a driver, in general, is to regulate power supplied to fixtures, thus protecting LEDs from damage due to overcurrent. They also provide LED lighting with the type of power required (DC power). In more technical terms, remote drivers are used in low-voltage LED lighting to convert AC voltages of 120V AC - 240V AC into low-voltages of DC ranging from 12V DC - 60V DC. In line-voltage powered LED fixtures, drivers are integrated into an electrical load. Next, we’ll compare remote and integrated drivers, and their purpose in low-voltage LED lighting.
Remote drivers can be located over 300 ft. away from an LED fixture. They regulate power, and send direct current (DC) at the ideal voltage to an electrical load. Low-voltage LED lights, such as downlights and panel lights, usually operate on remote drivers. Integrated drivers, on the other hand, still regulate power, but are integrated directly into a fixture, and cannot be removed. This is the case in line-voltage LED fixtures.
Although Power over Ethernet (PoE) lighting falls into the category of low-voltage LED lighting, it’s the exception to the rule because it operates on integrated drivers called PoE PDs (Powered Devices). PoE lighting must use integrated drivers because every light fixture has a unique IP address for control and makes a handshake with a PoE switch before power is sent to it. And because these drivers (or PoE PD’s) regulate voltages within the fixture, PoE lights have integrated drivers.
Learn more about remote power systems for applications beyond lighting, here: The Most Efficient Remote Power Systems
Low-voltage LED lighting is often used when fixtures are difficult to reach with line voltage electrical conduit or mechanically protected cable, such as in display or landscape lighting applications. It’s also used when there isn’t space for LED drivers near the fixture location. When it’s appropriate to use low-voltage LED lighting, it can provide all the benefits of line voltage LED lighting, but there are some disadvantages when it comes to distributing power to low-voltage fixtures. The two main categories we’ll use to compare line voltage and low-voltage LED lighting are: efficiency and lifespan. Additionally, we’ll compare them with respect to safety and ease of relocation.
Low-voltage LED systems have a benefit over line-voltage systems when it comes to electrical efficiency and the fixture’s luminous efficacy (lumens/watt). This efficiency benefit comes from the fact that a single AC-DC power conversion (rectifier) can be used to power all of the fixtures in low-voltage LED applications. Larger converters are typically more efficient, because space constraint is not a challenge. On the other hand, in line voltage lighting systems, each fixture requires an individual AC-DC conversion, to fit in a small space. These small, individual converters can range anywhere from 50%-85% in efficiency, wasting up to half the power consumed by a fixture. Additionally, this energy is wasted in the form of heat, which wears down drivers overtime and, the more energy wasted by a driver, the more quickly drivers are worn out (and the faster line voltage LED lighting, or any fixtures with integrated drivers, dies). This is also what causes these fixtures to flicker. Thus, the fact that line voltage LED lighting typically requires integrated drivers, is essentially what makes powering it less efficient than powering low-voltage LED lighting. When drivers regulate power remotely from a fixture (as they do in low-voltage LED lighting applications), fixtures are getting the DC power they need right off the bat, without being exposed to heat emitted from inefficient, integrated drivers.
On the other hand, it’s worth noting that there is more voltage drop and line losses along cables that distribute lower voltages. So, in low-voltage LED lighting applications that involve remote drivers, there could be significant voltage drop along cables between the remote driver and the fixture, if the distance is long enough. In higher voltage systems, such as line voltage LED lighting, less line losses occur. Ideally, the infrastructure to power LED lighting would be able to provide relatively high voltages of DC power safely along cables. This would reduce line losses related to both low-voltage, and AC power.
See below for a video breaking down the 3 major types of line losses:
In addition to low-voltage LED lighting (powered by remote drivers) being more efficient, this lighting also has a longer lifespan than line voltage LED lighting with integrated drivers, meaning fixtures need to be replaced less often. In many cases this longer life time is up to 2x. This saves money that would’ve been spent on replacing fixtures more frequently, and reduces maintenance time that would’ve been spent doing so as well. The reason low-voltage LED light fixtures have a longer lifespan than line-voltage fixtures, comes down to the same reason they’re more efficient. When drivers are located separately from fixtures, they can be made to have higher efficiencies (because they can be bigger), and thus don’t heat up as much. Heat is the main culprit in failed LED drivers, because the electrolytic capacitors (key component in the driver) have decreased lifespans at higher temperatures.
Low-voltage LED lighting is generally safer than line voltage LED lighting because it operates at less than 60V DC. This fact qualifies it as an extra-low voltage (ELV) system, meaning that voltage is low enough that it does not pose a high risk of electrical shock. Being an ELV system, it’s also easier to relocate the cables involved in low-voltage LED lighting because, firstly, it’s less risky to do so and, secondly, moving them doesn’t require moving conduit or mechanically protected cables. On the other hand, line voltage LED lighting is powered by lines carrying 120V - 240V AC.
It’s very common to power low-voltage LED lighting with a Class 2 power system. Class 2 power systems are power systems that have been given a Class 2 rating, as defined by the National Electrical Code (NEC) in the US. Like Class 1, and 3 rated electrical systems, Class 2 systems are power limited, but they have the benefit of being considered safe from both a fire and electrical shock, and having the ability to distribute DC power. Two examples of a Class 2 power system are Power over Ethernet (PoE), and Cence LVDC (low-voltage direct current). PoE has been gaining popularity over the past few decades, but it’s important to consider the benefits and drawbacks to using PoE to power low-voltage LED lighting before defaulting to it.
Next, we’ll compare PoE with Cence LVDC with respect to a few major considerations:
When it comes to saving on cable in lighting projects, the ability for a power system to daisy chain light fixtures can save a lot of cabling. This is because, with daisy chaining, less “home-runs” of cable are necessary, and cable management is also less complex. PoE systems are not practical to daisy chain because each PoE powered device (PD) would need to have built-in power source equipment to manage both power and data received by the fixture. Cence LVDC, on the other hand, is a Class 2 power system that can easily daisy chain LED fixtures.
Terminating each cable in a PoE system with RJ45 plugs is essential. However, 100W PoE cables need heavier gauges than typical Ethernet cables, so the RJ45 plugs utilized in PoE systems come at a higher cost than the average ones; they cost about $20 per unit. In contrast,, Cence LVDC, does not require cable termination (or RJ45 plugs).
Only PoE compatible light fixtures can be powered by PoE. These are specialized products that can be harder to find, and are more expensive than typical low-voltage LED fixtures. Conversely, Cence LVDC can power most remote driver light fixtures.
In PoE systems, each Ethernet port on a PoE switch can only control one light fixture. This makes many ports necessary if using PoE for a larger lighting project, and can unnecessarily increase network overhead and IT management costs. An alternative solution to provide both power and data to a lighting project, is to use secure wireless lighting controls alongside a Class 2 power system. Cence LVDC offers this feature, but the lighting project must allow groups of light fixtures to share a single IP address.
If you’d like to read our full article comparing PoE to other Class 2 power systems, like Cence LVDC, you can check out our in-depth article here: Power over Ethernet Vs. Class 2 Power Systems.
The optimal power system for low-voltage LED lighting maximizes the efficiency and lifespan of light fixtures, and does so safely.
Class 2 power systems may seem like the ideal power system for low-voltage LED lighting projects, which only require less than 100 W anyway, but high-voltage DC power systems can complement Class 2 power systems if used in conjunction. Delivering higher voltages, and DC power, reduces line losses, so it would be beneficial for a system like this to act as a backbone for an electrical project that requires long lengths of cable. For the “last-mile” of the system, voltages would be stepped down, and a Class 2 power system could be used. Let us explain further.
Up until recently, a power system that safely distributes high voltages of DC power hasn’t been standardized, and very few existed, but the National Electrical Code (NEC) in the US changed that when they released their most recent edition in February 2023. This edition includes a new class rating (Class 4) that can be found in Article 726, and it can be applied to direct current (DC) power distribution systems that have fault management, and can deliver up to 450V DC. Additionally, UL published standards that support this addition to the NEC (under UL 1400-1 and UL 1400-2). Class 4 rated power systems are ideal for powering low-voltage LED lighting because they reduce the number of necessary AC to DC conversions, as well as line losses along cables that would’ve occurred if low voltages were to be carried through cables. Class 4 power systems not only make a great alternative (or addition) to traditional low-voltage power systems, they could also compete with line voltage LED lighting infrastructure because of their high voltage capabilities and safety features.
One of the major hurdles to developing a Class 4 power system (that could deliver up to 450V DC safely along cables) was developing the safety features to make it as safe as a low-voltage LED system. Fault managed power (FMP), however, seems to be the solution. You can read more about fault managed power systems in our article about them: [link to fault managed power systems article]
Another reason Class 4 power systems could be the ideal system to complement Class 2 power systems when powering low-voltage LED lighting, is their efficiency. For a power system to be efficient, ideally high voltages of DC power would be carried through the cables of the system. This is because the least amount of line losses occur in lines carrying higher voltages, and DC power inherently suffers less line losses than AC power. Additionally, the AC to DC converter (existing in a light fixture’s driver) would ideally be remote. The two main advantages of remote drivers are that, firstly, if any AC to DC conversions are necessary, heat emitted from any inefficiencies causes thermal runaway in the driver, which eventually leads to its failure. Secondly, these drivers would be sending DC power directly to LEDs (DC powered loads), so LEDs would be getting the type of power they need, right off the bat. This is especially beneficial if powering multiple LEDs at once. To explain further, if each individual LED fixture has an integrated driver, conversions must be made individually for every fixture but, if one centralized conversion is made by a remote driver, multiple LED fixtures can be powered at once using the same DC branch circuit. This reduces the number of conversions, thus eliminating inefficiencies caused by them.
If you think you have a project that could benefit from a Class 4 rated power system, contact Cence Power to ask a specialist.