Bear in mind that commercial insurance can be first party (premises, property) or third party. Assuming you mean third party the exclusions tend to fall into various categories:
1. So-called peak risks such as:
- nuclear risks
2. Own actions such as:
- deliberate and/or fraudulent acts (e.g. own fraud, libel)
- pure contractual liability
- IP infringements
3. Other covers that are usually bought separately (e.g. Key Man, Workers Comp, D&O liability).
For first party covers you would tend to find a limited inclusion for Business Interruption and Contingent Business Interruption - here you should read the wording very carefully.