You should avoid these things inside your house during a thunderstorm.
According to the National Oceanic and Atmospheric Administration, there's a list of precautions you should take indoors.
1. Stay off corded phones, computers and other electrical equipment that put you in direct contact with electricity.
2. Avoid plumbing, including sinks baths and faucets.
3. Stay away from windows and doors and stay off porches.
4. Do not lie on concrete floors or lean against concrete walls.