Given a AC to DC power adapter like those found powering most electronics such as a network switch, could the 2 wires leaving the adapter be split into 8 wires of smaller diameter ( 4 wires per each original wire ) and then rejoined their original 2 wire counterparts further down the length of the wire without any additional "stress" / safety concern?
This question assumes that the volume per length of wire for the 4 wires equals or is greater than the original wire's volume – For example, original wire of 2mm and then each of the 4 are 0.75mm resulting in a larger total 3mm when all 4 wires are added together.
Also assumes that all wires are properly shielded given their diameter.
Goal is primarily to see if a "flatter" set of smaller wires can replace a single, thicker wire and also to increase understanding of the safety ratings / concern over handling current. For sake of discussion, please assume wire length is 15 feet and the voltage / amperage is 12 V and 4 A.
Best Answer
First of all, don't tamper with AC. Just making sure. My answer is talking about the DC side, which in this case is 12v and classified as "LVDC", a low enough voltage that is safe to work with.
On to your question, yes, this idea will work. At least when using multiple-pin connectors, this is called "current sharing". You can think of each wire being a resistor, with (in this example) one resistor being replaced by 4 in parallel. There will not be a problem, as long as the resistors are more or less equal.
This can become a problem (usually in larger loads, or with extremely small conductors) if your resistance in one of the four resistors starts going up (for example, is completely disconnected, heats up or is broken.). In a vicious cycle commonly called "thermal runaway", you can end up having more current on the individual wires than they can safely handle, thus heating them up, and having their resistance go up, or even melt themselves.
-Source: EE student and designer, have done this myself on multiple occasions, also fried many LED's due to unstable current sharing.