All of the following are duties of the insured following a loss in a standard fire policy EXCEPT

A signed proof of loss is indeed a requirement following a loss, but the specific timeline and conditions may vary depending on the insurer's policies and the specific terms of the standard fire policy. Generally, the duty to submit a proof of loss is crucial, but it does not always mandate a 30-day submission requirement in every situation.

In many instances, insurers will have guidelines that dictate the timing and nature of this submission, accounting for varied circumstances surrounding the loss. As such, while submitting a signed proof of loss is essential and typically expected, the specific requirement of doing so within 30 days is not a universal duty across all standard fire policies, making it the exception in this case.

The other duties listed, such as notifying the insurer promptly, protecting property from further damage, and providing a detailed inventory of damaged property, are standard requirements designed to help the insurer assess the claim accurately and ensure that the insured takes reasonable steps to mitigate further loss. These actions are critical to the claims process and reflect the policyholder’s obligations in the event of a loss.