Generally speaking, yes, outdoor wiring needs to be in conduit to protect it from physical damage. Type UF cable needs conduit when exposed, no need for conduit on the buried sections.
Even though standard NM cable has a vinyl outer jacket and waterproof insulation around the individual conducting wires, it is not intended for use in outdoor locations. Instead, cables must be approved for outdoor use. And when using conduit, there are additional rules that must be followed.
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Frequently Asked Questions
Can you bury cable without conduit?
At 24 inches you can bury underground feeder cable, using PVC conduit to 18 in. ... However, if you only need a power supply (without wires to control lights from inside the house,) you can use a direct burial cable, placed in the soil without conduit.
How deep do I need to bury electrical conduit?
In general, bury metal conduits at least 6 inches below the soil surface. You may also run them at a depth of 4 inches under a 4-inch concrete slab. Under your driveway, the conduits must be below a depth of 18 inches, and under a public road or alleyway, they must be buried below 24 inches.
Do you have to use conduit on ceiling?
Smaller cables shall be run either through bored holes in joists or on running boards. So basically if the cable is on the ceiling, it does not require conduit. If the cable is run along walls, it requires some form of protection. This protection can be conduit, or some other form of protection.