wires

I have a box of electric wires that one of my boys like to get into but those are wires that I need such as chargers, amp wires and head phones. This question is less about if rats will chew wires and more about should they. Is it dangerous? Can it be harmful? If its not I might make a specials...

I left my rats for one second I turn back around... and my charging lead is chewed in half!!! I don't care about the lead... There doesn't seem to be any signs of pain in the rats but I was wondering if they will be ok as I am really worried...