My understanding is that non-waterproof metal flex can be used outdoors under two conditions. First, the wires inside must be suitable for that condition. Second, the flex must be installed in such a way as to disallow the entrance of water into boxes/equipment. As an example if the metal flex came out of the bottom of one J-box and went up into the bottom of a second J-box, and THHN wire was used, then the installation would be acceptable. I don't understand why this is allowed when there are better, readily available options. Is metal flex really that much cheaper and easier to use than liquidtight or sealtight?
