A common carrier may not limit his legal liability by any notice given either by publication or by entry on receipts given or tickets sold, provided that a common carrier may limit his liability by means of an express contract; provided, however, that a motor common carrier of household goods and office furnishings may require a shipper to declare a lump sum value for the shipment prior to loading or accept the per pound released value as provided in the terms of the bill of lading contract for the purpose of limiting its liability.