For large installations of 5V LEDs, this PixLite page suggests using "power injection" from supplemental power supplies. Their wiring sample says:
Note that the DC ground of all power supplies used should be connected
together to provide a single common ground reference. In addition to
this, the positive output from each power supply should be isolated in
order to avoid differing voltage potentials occurring across multiple
power supplies, which could result in damage.
I am trying to imagine a way in which "damaging" voltage (which I assume would mean significant overvoltage) could be developed by injecting from identical power supplies without isolation on the positive side if they share the same ground reference. Is that possible, and if so then how?
Best Answer
As the power supply is a low impedance source: even small differences in voltage output can result in large currents flowing between them if the supplies are connected in parallel. Depending on the design of the supply this may cause damage.
Rather than connecting the supplies as shown it would be better to connect the power and ground at the strip for each auxiliary supply. This will keep the ground current in the common ground within sensible limits and as the power ground is also used as a signal ground will keep the ground noise down for signalling.