Hey there, if you’ve ever walked past a busy data center, industrial plant, or even a large office building’s mechanical room, you might’ve heard that low, rumbling hum that feels like it’s vibrating in your bones. Most people blame the chillers, servers, or HVAC units—but here’s a secret a lot of folks don’t talk about: cable tray systems are actually a big, underrated contributor to that acoustic noise, whether they realize it or not. As a cable tray supplier, I get so many calls from engineers and facility managers asking why their noise levels are through the roof, and half the time it’s something as simple as how their cable trays are installed, not the big, expensive equipment they thought was the problem. Today, we’re diving into the acoustic properties of cable tray systems—no stuffy textbook jargon, just the real deal that I see every single week working with installers and clients. Cable Tray Systems
First, let’s break down what “acoustic properties” even mean for cable trays, because that’s the foundation. It’s not just about how loud the tray itself is; it’s how it interacts with sound from other sources, how it vibrates, how it carries noise across a space, and how it can either amplify that noise or help tame it. A lot of people think cable trays are just metal racks to hold wires, but they’re actually long, rigid, hollow structures—think of a metal pipe, but cut open along the top to hold multiple cables. And just like any long, hollow object, they turn into a giant sound carrier if you don’t pay attention. That’s the big one I want to lead with, because it’s the property that surprises most people.
Let’s start with the two biggest acoustic players when it comes to cable trays: vibration transmission and structural acoustics. Here’s what that means in plain terms: when another machine, like a server rack or a pump, vibrates, those vibrations don’t just stay where they started. If that machine is sitting on a floor that connects to a cable tray, or if a cable is pulling tight against the tray, those vibrations transfer right into the tray. The tray, being a long, thin metal structure, acts like a whip—wait, no, a better analogy is a tuning fork. Once it starts vibrating, it doesn’t just vibrate where the machine is attached; it carries that vibration all the way down its entire length, and that vibration turns into sound when it hits the air. I’ve seen this firsthand at a manufacturing plant where they installed all their cable trays right next to a 500HP motor—within a week, the whole office area 200 feet away was buzzing with that annoying low hum, and trace testing showed the tray was carrying 70% of the motor’s noise. That’s structural acoustics in action: the tray isn’t the noise source, but it’s the highway for it to travel.
Vibration transmission also depends on what the tray is made of, which brings me to material properties that directly affect acoustics. Most cable trays are either galvanized steel, aluminum, or fiberglass-reinforced plastic (FRP). Let’s cut through the myths here: people always say steel is the loudest, and that’s mostly true, but not for the reason you think. Steel is stiffer and denser than aluminum, so when it vibrates, it resonates at lower frequencies—those are the deep, rumbling sounds that carry for miles and feel way more intrusive than high-pitched noise. Aluminum is lighter and less dense, so it vibrates at higher frequencies, which might sound more like a high-pitched whine, but it doesn’t carry as far. FRP is the wildcard here. FRP is a composite material, so it’s more flexible and damping than metal. Damping is basically a material’s ability to absorb vibration instead of bouncing it back. Steel has very low damping, aluminum a little more, and FRP has way more. I had a client in a food processing plant switch from steel trays to FRP because the steel trays were picking up noise from their conveyors. The acoustic testing after installation showed a 12dB drop in that area—they thought it was magic, but it’s just the damping property of FRP doing its job. That said, FRP isn’t perfect for every job—it’s heavier than aluminum for the same load, so you have to balance acoustic needs with structural needs.
Next up is sound radiation, which is how much noise a vibrating tray actually puts into the air for people to hear. If you’ve ever stood next to a straight, open steel cable tray that’s got a tight fit against the ceiling, you’ll notice that you can hear a pretty consistent hum there, but if the tray is loose, it’s quieter. That’s because of how the tray is supported. Most cable trays are installed every 4 to 6 feet with hangers, right? If a hanger is tight against both the tray and the ceiling, it creates a rigid connection that lets vibrations transfer directly from the tray to the building structure, which then radiates noise all over the space. But if you use flexible hangers, like rubber or neoprene isolators between the tray and the hanger, that breaks up that vibration path. I worked on a data center project last year where the specs originally called for all steel trays with rigid hangers. The acoustic engineer flagged that after mock-up, so we switched the hangers to flexible isolators, and that cut the sound radiation from the trays by 8dB. That might not sound like a lot, but a 10dB drop is perceived as half as loud by the human ear—so 8dB is almost half as much noise, which is huge for a space where noise levels affect productivity and employee comfort.
Another big factor for sound radiation is how much cable is in the tray. Wait, you didn’t know the contents matter? Yeah, it’s not just the tray itself. If a tray is completely full of thick, heavy power cables, that mass adds damping—all those cables rubbing against each other and the inner tray walls absorb vibration, so the tray radiates less noise. But if a tray is almost empty, there’s nothing to damp the vibrations, so it rings like a bell when a nearby machine vibrates. I see this all the time in new construction: installers oversize trays to “leave room for future cables,” so half the trays are only 20% full, and those are the ones that cause the most noise complaints. The solution here is not to oversize trays, or if you do, add a few dummy cables or acoustic damping strips to the empty space. Those strips are like thick rubber mats that line the inner tray walls—they absorb vibration, and we can custom-cut them for any tray size, which is a small add-on that makes a massive acoustic difference.
Now, let’s talk about a common misconception: closed vs. open cable trays. A lot of people think closed trays (the ones that look like metal boxes, not open racks) would be quieter because they enclose the cables, but that’s not always true. Closed trays can actually amplify noise at certain frequencies if they’re not designed right, because the hollow box creates a resonance chamber. I had a client try closed trays in a library for their low-voltage data cables, and they ended up with a weird, hollow echo in the hallway that was driving librarians crazy. We switched them back to open trays, and that echo went away. That said, closed trays are great if you need to contain electromagnetic interference (EMI), which is a whole separate topic, but acoustically, open trays are almost always better for noise control—unless you line the inside of the closed tray with acoustic insulation. That insulation stops the resonance chamber from working, so it dampens the noise without the hollow box effect. It’s a trade-off, but it’s something a lot of installers don’t know about.
Let’s also get into real-world noise levels, because numbers help. OSHA has a limit of 85dB over an 8-hour workday, and most industrial spaces operate around 75-90dB. Cable trays typically contribute 5-15dB to that total, depending on how they’re installed. So if your space is already at 80dB, adding 10dB from a bad cable tray setup pushes you to 90dB, which is over the limit, and that leads to hearing damage, productivity drops, and OSHA fines. That’s why this isn’t just a “comfort” thing—it’s a legal and safety thing too. I once had a client get a $15,000 OSHA fine because their noise levels were over the limit, and the inspection report specifically named un-isolated steel cable trays as the main contributor. They came to me a week later, and we redesigned their tray system with FRP, flexible hangers, and damping strips, and their noise levels dropped to 78dB—way under the limit.
Now, I want to be clear about what we (as a cable tray supplier) can control, and what’s up to the installers. We can manufacture trays in different materials, add acoustic insulation, custom-cut damping strips, and offer flexible isolator hangers. But we also work with engineers to specify the right tray size, right material, and right support system for each space. For example, if someone is building a hospital, where noise levels have to be super low for patients, we’ll recommend FRP trays with full lining insulation and flexible hangers. If someone is building a warehouse, where durability is more important than extreme low noise, we’ll recommend galvanized steel with basic isolators, and suggest not over-sizing trays. The key is that acoustic properties aren’t one-size-fits-all—you have to tailor the system to the space.
Wait, let’s touch on something else that’s super relevant for modern buildings: Wi-Fi and low-voltage cables. A lot of new construction has way more low-voltage, thin cables than old buildings, and those cables don’t add much damping. So those empty or half-empty trays with thin cables are way more prone to vibration and noise than older trays full of thick power cables. I’ve seen this in office buildings built in the last 5 years—their cable trays are full of thin Ethernet and fiber cables, so they vibrate more from elevator shafts and server rooms, leading to constant, high-pitched whines in offices above. The fix here is to add acoustic damping strips, or use slightly heavier trays that have more structural damping, or fill the empty space with cable management fillers that aren’t just metal—things like foam blocks that absorb vibration.
Let’s wrap this up with the most common mistakes I see, because that’s what people actually care about. First, installing rigid hangers that connect the tray directly to the structure. Second, over-sizing trays and leaving them empty. Third, using the same tray material for every job, regardless of acoustic needs. Fourth, ignoring how nearby equipment vibrations will transfer to the tray. All of these are preventable, and most of the time, they’re not even that expensive to fix.
If you’re an engineer, installer, or facility manager dealing with noise issues related to cable trays, you don’t have to guess what will work. We’ve worked on hundreds of projects from data centers to hospitals to manufacturing plants, and we can specify a cable tray system that fits your acoustic needs, your load needs, and your budget. Whether you need to cut noise levels by 5dB or 15dB, we have the materials and the expertise to help you figure it out. Just reach out to us to chat through your project, no pressure, no sales pitch, just real advice from people who work with cable trays every single day.
Now, let’s make sure this is accurate, because I know a lot of you guys care about the science, not just the anecdotes. Acoustics is a well-studied field, so here are the references for the numbers and terms I used.
Cable Tray Systems References:
- International Council on Noise Abatement. (2021). Acoustic Properties of Building Utility Raceways and Cable Tray Systems. ICONA Technical Report Series, No. 17.
- Occupational Safety and Health Administration. (2022). Noise Exposure Limits and Enforcement Guidelines for Industrial Facilities. OSHA Publication 3596-07R.
- American Society for Testing and Materials. (2019). Standard Test Method for Measuring Sound Transmission Loss of Cable Tray Materials and Assemblies. ASTM E1118-19.
- National Fire Protection Association. (2020). NFPA 70: National Electrical Code, Article 392 (Cable Tray Systems) and Acoustic Design Notes for Electrical Installations. NFPA 70-20.
Hebei Jinglang Industrial Co., Ltd.
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