Most of the non-metal conduit is made from a hard-wearing plastic like PVC. It is a practical choice in areas that cannot accept metal, such as a hospital MRI room. Also, it is useful for encasing in concrete under a driveway, or areas that are often in contact with water. PVC conduit is not only watertight, but is also able to stand up to long-term exposure to water without experiencing issues with corrosion or rust.
The preferred type of non-metal conduit is based on factors like the overall installation cost, corrosion resistance and mechanical protection. Here are a few of the most popular types of non-metal conduit:
Rigid non-metal conduit (RNC)
The rigid non-metal conduit is the most cost-effective option in the market and practical for those working on a tight budget. The fittings are easily attached together with a solvent which is a lot faster than the methods used to secure the separate pieces of metal conduit. Once the solvent is welded and cooled, the joint is certain to be watertight for the long-term. This type of conduit can be heated to make it more pliable and easily bent to fit the awkward spaces.
The standard size of this tubing is schedule 40 or 80. There is also the option to use different wall thicknesses and sizes. However, the thick tubing can start to get difficult to heat and bend, so is more practical for the straight routes.
Even though the RNC is a versatile option in a variety of situations, it does have the disadvantage of not being so effective at standing up to bumps or knocks compared to the metal alternatives. It is not a practical choice for grounding, so a special conductor is necessary. Also, when exposed to heat the plastic can expand and contract, so must be considered when planning the long runs.
Electrical Non-metallic Tubing (ENT)
The electrical non-metallic tubing is made of thin tubing like material that is flexible and easy bent to shape. But, the bend isn’t likely to stay permanently. This tubing is useful to get around obstacles without needing to weld or cut. Plus, it is quick to install with snap-in connections, which does mean it isn’t a practical choice for the moist environments. The preferred option for the mildly damp areas is the liquid-tight flexible non-metallic conduit which is built with a proper seal to protect against water entry.