Said Company, its successors and assigns, shall throughout the term of the franchise distribute to all consumers gas of good quality and shall furnish uninterrupted service, except as interruptible service may be specifically contracted for with consumers; provided, however, that any prevention of service caused by fire, act of God or unavoidable event or accident shall not be a breach of this condition if the Company resumes service as quickly as is reasonably practical after the happening of the act causing the interruption.