|This is more of a question for your lawyer and insurance carrier. Your business plan outlines what your risk exposure entails which then the carrier will determine how best to insure you. The lawyer determines how to minimize your risk by contract wording and scope definition.
Ask your lawyer and determine this coverage by how your net worth can survive a lawsuit to your business. Is your business a LLC or incorporated?
Personally, I would never call myself a thermographic consultant without some E&O to protect my ass...sets.