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by NwtnsMthd 2381 days ago
My first impression is that it smells like BS but let's take a closer look.

CAT6 cabling uses 4 pairs of AWG 24 wire. This type of wire typically comes with two options for insulation 250V and 600V, Let's be optimistic and use the latter. The maximum recommended current for AWG 24 wiring is 0.577A [1], as a reference PoE specs use 0.3A (if I remember correctly). Using these assumptions our maximum power transmission would be 4 (pairs of wire) * 600V * 0.577A = 1384.8W, this doesn't include power losses inside the wire itself. Belden's descriptions seem to indicate that power transmission is multiplexed in the time domain, which would reduce the power transmission capability even further.

Current limits on wiring are semi-arbitrary, what it really comes down to is how much heat generation is tolerable in the wires and the environment in which they reside. If we were to ignore the suggested current limit of 0.577A per core then it is possible to transmit 2000W. More specifically you would need 0.833A at 600V in 4 pairs of wire to get 2000W.

TLDR: The claims seem dubious. It is possible if the current limits for AWG 24 wire are are exceeded by about 2x.

[1] https://www.powerstream.com/Wire_Size.htm
2 comments
lopmotr 2381 days ago
There are special thicker 16 and 18 AWG Digital Electricity cables [1], so you probably wouldn't get that 2kW with CAT6 unless it's just peak power with a low duty cycle. They are rated for 300V so they might actually use close to that.

[1] https://www.belden.com/products/enterprise/copper/cable/de-c...

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NwtnsMthd 2380 days ago
Oh, that makes more sense!

4 * 300V * 2.3A = 2.76kW

It looks like it's totally doable with those cables! But if they're running 300V DC through there... may as well just run 120Vac. The only benefit I see is that they can detect faults on the transmitting end in a sophisticated manner.

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Gibbon1 2381 days ago
I've come around to the idea that some type of power over Ethernet is probably the correct solution for low voltage house wiring. There is an automotive standard IEEE 802.3bu-2016 which supports up to 55 watts.

The other advantage it that solves a lot of the IoT last 25 feet problem. Because it's both power and a data link.

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