The recommended solid wire size is 22 Ga and those real floppy wires are like 10 strand wound together to make a 30 ga wire I only use them for signal wiring or the 3In./75 mm power wires from a rail to a light load. When I need to use a back-light I use another separate power supply usually a breadboard "Plug-In" that has a 2.1/5 mm coaxial power jack, a power switch and a USB connector, the ones I have are for the 830 tie point b'boards and acn make one rail 5V and the other rail 3V3 or both rails 3V3 and they only usually cost $2.00 - $4.00.
Bob