Metric Electrical Conduit Size The electrical conduit is a vital part of any wiring effort. To get it right, you need to understand metric electrical conduit size options. Electrical conduit refers to the tubing that contains electrical cable and wiring. Conduit serves a variety of purpose. It keeps the electrical cable contained and orderly. It protects the cables and provides fire protection where the cables pass through walls.

Conduit is also intended to protect wiring from moisture.Electrical conduit comes in several different types. EMT or electrical metallic tubing is a common type of metal conduit. There is also flexible metal conduit, galvanized rigid conduit, and intermediate metal conduit. The galvanized rigid conduit (GRC) is sometimes made with aluminum. The most common non-metallic conduit is made with polyvinyl chloride (PVC)

Prior to 2002, The National Electric Code (NEC) specified conduit sizes in the inch-pound measurement system also known as the English system. This created certain problems as the majority of the world used the International System of Units (SI) which is also called the metric system of measurement. The Code was changed in 2002 to include both systems.
This was done to make the NEC compatible with NFPA standards. NFPA is the National Fire Protection Association. NFPA uses the SI system of measurement. The idea was also to make the NEC more suitable for use in electrical codes around the world. This is another example of the impact of the increasingly global economy on standards and codes in the United States. Electrical conduit is still produced in both English and SI sizes.

The conversion of English measurements to SI sizes has caused some problems where extremely precise tolerances are necessary for proper connection. This has led to a division between critical and non-critical conversions in the codes. It is assumed in the years to come the SI system will replace the English system as the standard size measurement units in electrical conduit. There has been resistance to a conversion to SI in certain other areas, but the pressure of adhering to International codes and standards should provide the push to overcome lingering resistance.

source: www.electriciancompanies.com