It seems that a lot of people are wondering what the difference is between Power over Ethernet and class 4 (the new class proposed by the NEC). Basically the difference is power; PoE is 90 W MAX, and class 4 systems are up to 450 Volts, unlimited wattage. Even though class 4 is more powerful, it still only requires the same safety precautions as poe because typically a computer monitors for fault in the wire (including human touch), and power is shut off if a fault occurs. This is what makes it intelligent. It's also a DC power system (not AC). DC works better with our digital devices, as well as LED lighting, and is more energy efficient for many reasons. If you have any questions, I'm happy to answer them. I write tech articles about this kind of thing all the time, and work with lots of engineers who love to answer questions from curious people
Let’s get this straight. Power is interrupted AFTER the system detects touch contact. Current is unlimited. So this is safer? Yes you won’t die from fibrillation. It will just break your limbs from the force of contracting muscles never mind the burning tissue! So much safer.
DC has two fundamental flaws.
Originally Edison started power distribution with DC generators he called dynamos. As stated it worked great with electric lighting. But distribution was limited to a couple hundred feet.
Tesla introduced the AC generator, AC motors, and proved that Edison’s lights worked just as well on AC. In addition it could be distributed over neatly unlimited distance with a transformer. This seems like the end of the story.
Much later Tesla raised the idea that HVDC was superior to AC but conversion was an issue. Today AEP runs a huge multistate HVDC transmission system. One problem solved.
Still LED lights and some electronics hardly compares to HVAC, water heaters, clothes washers and dryers, refrigerators and freezers, and various kitchen appliances all of which run on AC and consume the majority of power. At a minimum we know that AC to DC and DC to AC power losses are 5-6% (VFDs do this). Imagine if we saved 3% on lighting and electronics by going to DC but lose 5-6% on the majority of large loads in the residence. Excuse me if I fail to see how this makes sense.