Gas Safe is a well known and highly respected register of gas engineers. By law all gas engineers have to be Gas safe registered. No other installers are tested and retested regularly in the same way as those who work on gas appliances, both commercial and domestic. The gas safe association not only exists to provide a register of qualified engineers, they also investigate illegal gas workers and unsafe gas work. Every installer who is gas safe registered has his own ID card, insist on seeing it.