Puppies like to chew anything they can, even electrical cords! If your puppy is chewing on an electrical cord, they can compromise the insulative coating of the wire and make contact with the conductive materials, resulting in an electric shock to the mouth. While this may deter him from chewing on cords in the future, you would be surprised how often it does not!
More importantly, receiving a shock from a compromised electric cord can result in severe electrical burns to your puppy's mouth, requiring veterinary attention. Even worse, a severe enough shock can be fatal to your new puppy. Even if your puppy does not manage to shock himself, chewing on electrical cords will soon become expensive, as electrical appliances are ruined by this dangerous habit.
Puppies chew for a variety of reasons. Like all babies, including human ones, when their teeth are coming in they experience discomfort that is relieved by chewing. Also, puppies are curious, and they have not yet figured out what tastes good and what is good to chew, so they are constantly investigating. Dogs and puppies also chew to strengthen teeth and gums, or to relieve boredom or anxiety. Puppies are easily bored or become anxious when left alone and taking precautions to avoid your young dog becoming injured from inappropriate chewing is necessary.
It is imperative that your puppy not chew electrical cords that could result in serious injury or even death from electrocution if he bites into an electrical wire. Because this is critical, supervising your puppy and preventing him from having access to wires is important. There are several strategies to keep wires away from puppy until he learns to leave them alone as he matures, including moving or covering wires or creating a safe wire-free zone for puppy. During training, you will want to provide alternatives, distract your puppy from wires, create a negative association with chewing on electrical wires, and create a command you can use to instruct your puppy to leave wires alone. A 'leave it' command can be used to direct your puppy not only to leave wires alone, but can be applied to lots of other dangerous or unsavory items he may be motivated to chew on, and is useful in a variety of situations.