what size cable for powering an LED sculpture?
Since you have 4 supplies, at a max of 180 Amps, that's only 45 Amps each, if equally divided. Since your intended application is much less than that (50% on at any given time, no White), you could do this with just 3 supplies, but since you have 4 might as well use them.

Due to voltage droop, from the resistance of a cable at high currents, you want to reduce the amount of current a single cable carries. So you will want to have multiple runs of power from a single supply to the LED strips.

Based on a quick calculation using 5VDC, 18 AWG, 5 Feet (10 Feet both ways), and 5 Amps, it shows a voltage droop of 0.32 Volts. So the LEDs, at the power input, will only see 4.68 Volts. If we cut the current in half, that's 0.16 Volt drop. More reasonable. If we go to 16 AWG, a larger size, at 5 Amps, it's still a drop of 0.2 Volts.

And that's before you get into the voltage droop from the FPC of the led strip itself.

So what you need is a short run of a large AWG cable, from the power supply to a distribution bus, and then multiple parallel runs of smaller cables to multiple spots in the LED strips.



Adafruit has a nice writeup of a similar project, using 80 Amps. Key points, see Power and Construction, but the whole thing is a good read.



Note the single AC Supply, to 12 AWG Fused cables, to a power distribution block, to multiple smaller cables to the led strips.

Keep the cables as short as possible to reduce voltage drop. If your Power supplies have an adjustment pot, increase the voltage to compensate. And the power supplies should be next to the sculpture. Having Mains AC power boxes installed near the sculpture isn't expensive and will be better.