Here are the most common types:
EMT: The electric metal duct is a rigid, thin-walled metal duct made of galvanized steel. Because it is thin-walled and lightweight, it is easily bent with a special tool called a channel connector, and can not be connected like a heavier channel.
FMT: A flexible metal channel has a spiral construction that allows the channel to flex easily, simplifying installation. These are typically used for short periods in open locations, such as cables for waste disposers and hot water heaters.
RMC and IMC: Medium rigid and medium metal ducts are heavy duty channels made of galvanized steel. They are used for structural piping that shields cables for home connections to utility service lines.
IMT has replaced RMC in new construction. RMC and IMC are combined with threaded connections.
PVC: Rigid PVC is a plastic pipe of similar size to EMT. It can be heated and bent and connected to a glued or spliced ​​connection.
LFMC: Flexible flexible metal ducts are flexible metal conduits coated with plastic sheathing to make them waterproof. It is used for outdoor cables that serve air conditioning units and other outdoor equipment.
