Does *USB C* cable thickness counts

[chefwong]

I'm setting up a new house with cables and such.

Normal spots where I usually may have a desk setup, or side desk charging bay, or long cord hidden by a couch

Riddle me this. Does *wire gauge* thickness of USB C wire matter for long term usability-durability.
Thunderbolt cable aside, alot of the various USB C cords I have that are 240W are quite supple and thin with a braided jacket, unlike some of my older Uni 100W cables that seem -thicker- that alot of the current cables I have for *fast charging*. I don't think it's just the braided jacket of the uni, but maybe it is and the wire gauge is the same.

 

[joevt]

Thicker wires allow for higher current but higher power charging just uses higher voltage (maximum current remains at 5A).
https://en.wikipedia.org/wiki/USB_hardware#Allowable_current_draw
https://electronics.stackexchange.c...-connectors-carry-100w-at-20v-without-melting

 

[dmccloud]

Cable thickness doesn't mean much specifically when it comes to charging, as only certain pins on the connector are used for that. Thicker cables are often also used for data transfer, so they have more wires connected to the plugs at either end of the cable. Adam Savage released a great video comparing Apple's Thunderbolt 4 cable to those offered by competitors, and there are start differences at play.

 

[theluggage]

Thicker wires allow for higher current but higher power charging just uses higher voltage (maximum current remains at 5A).

Well... yes, kinda - which is why they use super-high voltages for long distance power transmission, but it's all permutation of Ohms law ( V = IR ) which connects voltage (V), current (I) and resistance (R) and you can't completely separate those out.

So, for example, if the resistance of the wire is R, there will be a voltage drop of IR across the cable and - if that is too great - the device at the end won't receive enough voltage to work properly (or the charger will have to raise the voltage to compensate). The rate of power wastage due to heating in the cable is V x I which equals I^2 R - which is why its better to use higher voltage than higher current, but that's still proportional to R (which is going to decrease with thicker and/or shorter wires).

So lower cable resistance is still good - and thicker cables have lower resistance per unit length - so in general if you make a cable longer it may need to be thicker to minimise voltage drop and energy loss. Then, on top of that, higher voltage could reauire thicker insulation. Plus of course you also have to allow for likely failure modes, transients etc. & what the current/voltage spikes might be in those situations.

If you're dealing with a simple voltage source and a straightforward resistive load the math is fairly simple, but you're talking about USB-C then you've got regulated voltages and currents and smart devices at one or both ends that can vary the voltage and current they send. So you really have to just trust that the standards have made suitable trade-offs a certified USB cable of a given length and power rating is up to the job - and respect the maximum cable lengths in the specs.

 

[dwig]

Thru all of this you need to keep in mind that "thicker" can refer to several aspects of a bundled cable.

All of the discussion of wire guage (thickness) and power loss involves the cross sectional area of the metal conductors. It has absolutely nothing to do with the thickness of the insulating jacket around the wire and any additional mechanical abrasion jacket on the individual wires or the outer cable jacket, which itself may involve several layers. The overall outer diameter of the cable and its stiffness is influenced mainly by the jacketing and less by the actual electrical conductors themselves.