Does ISO 45001 cover electrical and fire or just medical?

The ISO 45001 provides requirements for companies to implement a management system to prevent injury and ill health in their employees; this does not certify the products and services that are provided by the company against any OH&S requirements. So, if you are purchasing a piece of equipment from an ISO 45001 certified company, this has nothing to do with the safety of that equipment.

However, the ISO organization has over 23000 standards, and many of these are used to provide requirements to certify equipment. It may be possible that you are purchasing a piece of equipment that is ISO certified for electrical and fired building codes to an ISO standard, however, you would need to compare the requirements of this standard against your NRTL certification requirements to ensure they are equivalent.

You can learn a bit more on what the requirements of ISO 45001 for an Occupational Health & Safety management system are in the whitepaper: Clause-by-clause explanation of ISO 45001:2018, https://info.advisera.com/45001academy/free-download/clause-by-clause-explanation-of-iso-45001