When we moved a couple of Spaghetti extruding machines, we had similar problems when they were installed. Rats or mice had made a nest in some conduit and gnawed through the cables.
Even though the machines were coming from a sister plant of a very big food manufacturer, it was decided to fumagate all equipment en-route, so imagine our supprise on the above.
As everyone is saying in Food Manufacturing you cannot have any infestation, not bug, bird nor animal. Protecting the cables is fighting one of the consequences not the cause. Rats bring disease and you could end up killing your customers.
There are very strict building regulations in the UK to protect against this, like insectocuters everywhere, all windows to have mesh, doors to have flaps and all entry points into the buildings to be sealed (usually with expanding foam).
Rat poison is used in the outbuildings, but for Christs sake it cannot be anywhere near food!!!!!