1.

Usually It's About $15-$35
2.

If you are a new utility customer or if you have a poor payment history, the utility company may require you to pay a deposit or get a letter from someone who agrees to pay your bill if you don’t. This is called a letter of guarantee.
The company’s policy for requiring deposits or letters of guarantee must be the same for all customers. If you are a new customer, the company can ask you for a deposit or letter of guarantee only if their policy is to ask all new customers to provide it.