Would highly recommend if possible to just use generic resources like "Electrician" and "Mechanic" in the resource sheet rather than individual names of people for your resources.

It's way more of a pain in the butt to manage when one of your named resources leaves the company, gets promoted to a different role, goes on parental leave, etc.

I would also recommend setting the calendar of all of these generic resources to your standard company calendar with holidays, the same as your project.