Case: As a result of previous satisfactory commercial relationships with New Enterprise Ltd, Wilfred entered into a contract with the company to install a new computer network including the provision of some new server in his offices.On the six previous occasions in the last two years when Wilfred has contracted with New Enterprise Ltd, the contract was always in writing and contained a clause stating that `New Enterprise Ltd is not liable for any financial or other losses caused by using any product supplied and installed by the company, whether as a result of negligence of the company or otherwise'.

The present contract between Wilfred and New Enterprise Ltd is not in writing, but when the new servers were delivered to Wilfred by New Enterprise Ltd, Wilfred was handed a delivery note by the New Enterprise Ltd's employee which contained a clause worded in exactly the same terms as the one quoted above.Wilfred did not read the delivery note.

The first time the new network was used after installation, a fire broke out in the office because of the negligent installation of the new server by New Enterprise Ltd's employee. Wilfred suffered serious burns as he escaped from the office and incurred expenses of $300,000 in refurbishing the damaged premises.

Wilfred sues New Enterprise Ltd for the breach of contract, but the company denies liability on the basis of the exemption clause in the contract.

Question: Many contractual clauses interpreted to exclude liability for injury, loss or damage.Explain the general rules which determine the effectiveness of such clauses.