one reason you don’t put romex in conduit is because it creates more heat and is not advised in conduit if you have conduit you can run insulated wires instead it’s probably cheaper. when you put romex inside conduit The Romex cannot breathe and retains too much heat. but of course they are insulated wires.Click to see full answer. Similarly, is Romex allowed in conduit?Romex is allowed in conduit, length is not an issue. Romex is not allowed in wet locations. The inside of conduit in a wet location is considered a wet location.Subsequently, question is, can you use indoor Romex outside in conduit? MC cable can be used indoors and outdoors because the ground wire is an insulated THHN THWN wire as well. The common use for MC cable is indoors because it can be used without conduit for a much easier installation. Subsequently, question is, what type of wire can be run in conduit? Wiring Used With Conduit The most common type of cable used in home wiring is non-metallic (NM), or Romex, cable. While NM cable can be run inside conduit, this is seldom done. The types of wire most commonly installed inside of conduit are THHN and THWN.How much Romex is in a conduit?The National Electrical Code has specific regulations for how many conductor wires can fit into within a conduit of each diameter size. A 1/2-inch conduit can hold as many as nine 12-gauge wires or twelve 14-gauge wires. A 3/4-inch conduit can hold sixteen 12-gauge wires or twenty-two 14-gauge wires.