IATSE Local 480 is what is referred-to as a Studio Mechanics local, which means that we cover myriad below-the-line positions within the film &TV industry. Other locals cover crafts like stagehands and broadcast technicians. If you’re looking for that type of work, you will need to find the IATSE local which has jurisdiction for crafts of those types.
Some crafts aren’t covered by a union at all. PAs, or Production Assistants, are a great example of a craft that is not covered under any union contract.
Since Local 480 doesn’t specifically find work for its members, you should be confident that you will be able to get hired on a consistent basis before you join the union. It’s like the old adage – It’s not what you know or who you know, but who knows you (and wants to hire you).