Before You Try Power Line Communication (PLC): 5 Key Challenges That Could Kill Your Connection
Power Line Communication (PLC) sounds like a dream: transforming your existing electrical wiring into a data network, saving you the cost and mess of new cables. It’s a brilliant concept with huge potential.
But in real-world situations, PLC doesn’t always work smoothly. There are several issues that can block or weaken the signal. If you don’t pay attention to these, your connection might be slow, unstable, or fail completely.
Here are five important challenges to watch out for when using PLC.
1. Signal Fade-Out Over Long Cable Runs
Even though power cables carry electricity well, they’re not perfect for carrying high-speed data signals. Over long distances—especially at the high frequencies used by PLC—the signal gradually fades. It’s like a voice getting quieter the farther it travels.
This signal fading depends on the cable material, the length of the cable and the frequency being used. As a rough guide:
- Over 100 meters, the signal may drop to about one-tenth (1/10) of its original strength.
- Over 400 meters, the signal may drop to about one-thousandth (1/1,000).
This kind of loss usually isn’t noticeable in homes, but it becomes important in large buildings like factories or offices with long wiring.
What you can do:
- Home use: Most homes don’t have cable runs longer than 100 meters, so the signal stays strong enough for PLC to work well.
- Industrial use: In large facilities with long wiring, using lower-frequency PLC is recommended. Some PLC systems like Nessum support long-distance communication by adjusting the frequency.
2. Too Many Paths for the Signal (Branch Splitting)
Your power wiring usually splits into many branches—especially at the breaker box. This is where the signal can get lost or bounced around.
At low frequencies (like normal electricity), this isn’t a big deal. But at the high frequencies used by PLC, each branch splits the signal more and more—like shining a flashlight through lots of mirrors. The more branches there are, the more the signal gets scattered and weakened.
In the worst case, each branch can reduce the signal by half, and if there are multiple branches in a row, the loss becomes exponential: With 20 branches, depending on the spacing between them, the loss can range from 1/20 to 1/1,000,000.
Note: This simplified estimate does not account for additional signal reflections from impedance mismatches.
What you can do:
- Home use: Most homes have up to 10 branches, and because the branches are spaced closely together, the signal loss is usually minimal and not a problem for modern PLC devices.
- Industrial use: In buildings with many and widely spaced branches, it’s a good idea to install signal repeaters (devices that boost the signal) in each breaker box.
3. Devices That Absorb Your Signal (Low Impedance Loads)
Most appliances and electronic devices (like TVs, washing machines, or PCs) are designed to reduce noise, which is good for safety—but not so good for PLC. These devices often include special parts (called X-capacitors) that “absorb” high-frequency signals like those used by PLC. As a result, communication signals are weakened to about 1/100 to 1/1,000.
Also, because these signals travel at high frequencies, even a short distance (like 30–50 cm) between the device and the outlet can change how much the signal is affected.
What you can do:
- Home use: Try using a short power extension cord (1 meter or so) between the outlet and your noisy device. It often improves the signal.
- Industrial use: Avoid plugging unknown or unfiltered machines into the same power line as your PLC device. You can also install special parts (like coils) to help keep the signal strong.
4. Noise from Electrical Equipment
Some devices, especially those with motors (like hair dryers or factory machines), create a lot of electrical “noise” that spreads into the power lines. This noise can interfere with the PLC signal, like trying to talk in a room full of shouting people.
Even advanced PLC systems can struggle with noise.
For example, Nessum is capable of maintaining communication even when the signal strength is reduced to less than one ten-billionth (1/10,000,000,000) of its original level. However, when strong noise is present, this high sensitivity can’t be fully utilized, and communication may still fail.
What you can do:
- Home use: Use noise filters (small plug-in devices) to reduce interference.
- Industrial use: Install EMC filters to separate noisy machines from your communication lines.
5. Transformers – The Signal Can’t Cross Them
Large buildings often use transformers to change high-voltage electricity into a lower voltage for regular use. Unfortunately, PLC signals can’t pass through transformers easily. It’s like trying to speak through a thick wall—most of the sound gets blocked.
What you can do:
- Home use: This usually isn’t a problem—homes rarely have transformers inside.
- Industrial use: Use wireless bridges (like Wi-Fi or specific PLC wireless products such as Nessum-Air) to send signals across different parts of the building.
Conclusion
PLC is a great way to turn your power outlets into network ports without installing new cables. But it’s not plug-and-play in every situation. Real-world environments—especially in industrial or complex buildings—introduce challenges like signal loss, noise, and electrical interference.
The good news:
If you understand and plan for these 5 key challenges, you can enjoy fast and stable PLC communication both at home and in large facilities.
About the Author
Kengo Tamukai is a senior engineer specializing in wired and wireless communication technologies. With over 20 years of experience in LSI design, system architecture, and technical marketing, his expertise spans SoC design, OFDM-based technologies, and hybrid communication systems, driving innovation in modern digital networks.
