TLDR: 32 feet, with 12 volt system using 150 or 300 LED tape.
The issue that always seems to come up with LED tape lighting is; “How many strips can be run together?”
Searching around on the internet doesn’t present a simple answer. Especially because there are reels with 300 LEDs and reels with only 150 LEDs. Surely if two reels of 300 LEDs can be run on a single 5 amp power supply 4 reels of 150 LEDs should be able to run on the same set up, but that’s not quite how it works.
As the length of the LED run grows the brightness of the LEDs furthest from the power supply will decrease due to internal losses no matter how much power is supplied. Our recommendation is to keep your install lengths under 32 feet (2 reels) then bump the brightness back up using an amplifier. This will allow longer runs without noticeable dimming. Another option to go further without amplifiers is to work with a higher voltage which we will talk about next time.