Complex sentence: An appliance with a permanently attached plug for use in one country cannot be readily sold in another which uses an incompatible wall socket; this requires keeping track of variations throughout the product's life cycle from assembly and testing to shipping and repairs.
Split into simpler sentences: An appliance with a permanently attached plug intended for use in one country cannot be readily sold in another country using an incompatible wall socket. This requires keeping track of variations throughout the life cycle of the product from assembly and testing through to shipping and repairs.