No, it is not recommended to use extension cords with Dyson vacuum cleaners. The manufacturer itself explicitly discourages customers from using extension cords to power corded Dyson vacuums or recharge cordless vacuums. This is because the use of an extension cable could cause over-current issues that may lead to technical faults with the cleaner itself. In simple terms, you could damage your Dyson vacuum by connecting it to an extension cable. So, if you find yourself in a situation where you don’t have enough cord to reach and clean a certain spot, the best thing to do is find a different outlet that will allow you to reach that area or consider investing in a cordless model.