PCA9685 Max Distance

I need to use 2 PCA9685 boards but not sure that the maximum distance the slave device can be from the master. Arduino to PCA9685 "1" is only about 3 inches. PCA9685 "2" need to be about 20-30ft from PCA9685 "1" What are my options here? would this work? I plan on using cat5 ethernet cable to complete the link because its currently the only wire i have with 5 or more wires. I think the devices both share the same I2C bus but im not sure

I2C is designed for communication between chips on the same board.
That said, I run two PCA9685 chips at the end of a ~5metre (15ft) Cat-6 wire, from a Mega, 24/7, no issues.
But 30 ft could be pushing your luck.

PCA9685 is "Fm+I2C", meaning that you can pull up the bus more (30mA) then common I2C (3mA).
Try 2k2 pull up at both ends of that long wire.
The next option (if needed) is to lower the clock frequency with wire.begin().
Leo..

Wawa:
I2C is designed for communication between chips on the same board.
That said, I run two PCA9685 chips at the end of a ~5metre (15ft) Cat-6 wire, from a Mega, 24/7, no issues.
But 30 ft could be pushing your luck.

PCA9685 is "Fm+I2C", meaning that you can pull up the bus more (30mA) then common I2C (3mA).
Try 2k2 pull up at both ends of that long wire.
The next option (if needed) is to lower the clock frequency with wire.begin().
Leo..

Would any of this change if i were to replace the arduino with a esp8266? By both ends of the wire do you mean on both SDA and SCL on both ends?

3.3volt Arduinos have less I/O drive current available, but it shouldn't be a problem.
Yes, both ends, to minimise signal reflections. So four 2k2 resistors.

Note that with a 3.3volt processor, the PWM output could also drop to 3.3volt.
Leo..