DCC - stranded or solid core wire?

My N-scale layouts have been running DCC for some time now. The experience is so much superior to analogue control that my G scale layout is going to be DCC controlled, too (sooner or later). At the same time garden trains require much longer cables. Can the choice of cabling affect the performance?

At first I thought that for my garden I simply needed a heavy duty cable - one that I can put into the ground and not worry about it too much. But then I heard of the skin effect and started thinking - perhaps the choice is not that obvious?

Taking the skin effect into account we end up with two main choices of cabling: solid core and stranded core. I've decided to buy them both and perform a test...

stranded core wire

solid core wire

I purchased 25 meters of each type. Both come from the same manufacturer and both are described as 2x2.5mm². I connected my N-scale layout using those cables and put one locomotive on which produced around 150mA of current. The result?

The difference isn't big but it's measurable. The stranded core wire gave ~0.15V more on the track compared to the solid core wire. In other words: seems the solid core wire gave more resistance to the DCC signal and caused a bigger voltage loss.

Is that much? Of course not. But this loss was measured for a really low current and in a G scale I'm expecting much more. And since the resistance of the cable is constant, the bigger the current the more loss there will be.

Is this really the skin effect? I have no idea... I know however that my stranded core wire gives better results in a test, so I'll use that for my garden trains.