How do you become a fire inspector?

Many states automatically appoint the local Chief of the Fire Department to be a Fire Inspector, so that would be one way.

However, there are other states where only a trained, certified and qualified individual can act as a fire inspector. In that case, you would need to take the necessary training, obtain a certification, then work under the supervision of another qualified inspector until you are deemed qualified.

In the USA there is an NFPA standard, 1031, which describes the basic requirements for competence as a fire inspector or plans reviewer. Some fire academies offer training courses to meet these requirements. Basic Fire Inspector training should be expected to take about 50 hours of classroom time, plus field trips, homework, and sample inspections.