Simple wiring question causing overthink (Repair-12vdc 3.3amp power supply has 2 pair of output wires to same device same location)

Its been 3 decades since I've done anything with electronics on the soldering pencil level, but I've been looking for a reason to pick it up again and here I am.
I'm repairing a simple 24-port network switch. I've replace a bulging power supply capacitor and all is well; before I put the case back together I wanted to ask if this situation is "normal"/acceptable practice. The device has 2 separate circuit boards inside of the case. One board is the 12vdc power supply and the other is the device (network switch). The manufacturer is using 2 pair of 20 gauge wire, 2 red and 2 black, to connect the power supply to the device. In other words the output of the power supply has 4 separate wires, 2 positive and 2 negative. They are soldered to the power supply circuit board at the same locations (2 pos and 2 neg) and terminate to a 4 pin female plug that supplies the load to the separate circuit board (network switch), which has 4 male pins soldered to it. They are then connected together with this 4 pin plug (2 pos and 2 neg). The specs say the max amps that will go over these wires is 3.3 amps at 12vdc. I don't believe 20 gauge is suitable. I don't like it, it seems sloppy, but who am I to say. Regardless is it acceptable procedure, especially for a well known manufacturer? This device, formerly non-working, lists retail at 350$. I am considering replacing this wiring scheme with 2 pieces of 14 or 12 gauge stranded with fuses and separating it into the pairs at the plug. Does this sound reasonable? I want it to be better than it was. (My opinion is that 20 gauge wire doesn't seem acceptable for 3.3 amps, even though its split over two pair of wires it could hypothetically all go over 1 pair.) Do you think I should use 2 pair, like the manufacturer, just a heavier gauge? Or just 1 pair and breakout at the 4 pin plug? If 2 pair would I need to use 4 fuses in that case? I hope this is a clear enough description. Thanks in advance.

by Solarsails
December 26, 2017

Are the two pairs of wires separately driven from two supplies or are they connected to the same supply?

by mikerogerswsm
December 26, 2017

H, sorry. There is only a single power supply. The positive output has 2 x 20 gauge and the negative output has 2 x 20 gauge wires that end in a single 4 prong female plug connector; the plug connector then powers a single circuit board.

by Solarsails
December 26, 2017

The manufacturer wiring is alright so long as the wires are of approximately the same length. The two paths will have roughly equal resistance and current will be shared.

by mikerogerswsm
December 26, 2017

That's interesting, I see how it would work but I could also see how it might be a flaw. It would help to know the specifics, ie are there separate circuits being powered and the amperage's being drawn; if its powering a single circuit then isn't it possible that one pair could take the "over"load on all by itself (the wires are of equal length, but couldn't all current flow on just a single pair even so?) Well, at any rate, if it isn't broke, then don't fix it. Thanks for your advice!

by Solarsails
December 26, 2017

Fortunately the coefficient of resistivity of copper is positive so a conductor 'hogging' the current would go infinitesimally higher in resistance and therefore share. Your solution of using thicker wires is equally valid, although on a new build might cause inventory problems.

by mikerogerswsm
December 26, 2017
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