Can MOVs (metal oxide varistors) be installed on the main AC power connector of a MNL controller?

Issue

Can MOVs (metal oxide varistors) be installed on the main AC power connector of a MNL controller?
Site has dirty power issues.

Product Line

TAC I/A Series

Environment

MNL controllers

Cause

Site has dirty power issues which are causing damage to the MNL controllers

Resolution

Although it's not a supported configuration, the MOVs are electronically capable of being installed on the MNL controller's main AC power connector.