I intend on using a circuit I designed for detecting an AC input line for control purposes. One of the inputs will be accessed by third party users and a cable might be connected with a decent length(>3m). The optocoupler I intend on using(VOL628A) has a diode max reverse voltage of 6V and the intended circuit is shown in the following image:

[![enter image description here](https://i.stack.imgur.com/WURhz.png)](https://i.stack.imgur.com/WURhz.png)

Since the diodes are connected in antiparallel, I was wondering if I should protect them from ESD. If an ESD voltage level should occur, each diode should clamp and protect the other. I know that the diodes react pretty slowly when it comes to ESD and there is a possibility that they get destroyed, but I was also struggling to find a TVS diode with a clamping voltage bellow 6V.

Therefore my question on whether or not should I use a TVS diode. Maybe you could recommend an alternative solution if TVS wouldn't help in this case.