Central Electricity Regulatory Commission (CERC) today fixed a margin of four paise per unit for electricity traders - a decision which is likely to hit the revenues of companies like PTC India, Tata Power Trading and Adani Exports."The move is aimed at protecting the consumers as well as providing reasonable return to traders. The margin does not include transmission charges, application fees, unscheduled charges and transmission losses," an official statement issued by CERC said."Electricity traders were generally not in favour of fixing of trading margin, but distribution utilities and consumers had welcomed the proposal of fixing margins," the release said, adding that it has decided to fix margins at a "reasonable" level of four paise per unit after examining various comments.