How frequently must electrical metallic tubing (EMT) be securely fastened?

The correct answer is that electrical metallic tubing (EMT) must be securely fastened every 10 feet. This requirement is in accordance with the National Electrical Code (NEC), which establishes guidelines to ensure the safety and integrity of electrical installations.

Fastening EMT every 10 feet provides physical support for the conduit, helping to mitigate any sway or movement that may occur due to mechanical vibration or environmental factors. It also ensures that the conduit remains securely in place, reducing the potential for damage to electrical wiring contained within and making sure that the entire system remains safe and compliant with code requirements.

In addition, securing EMT at specified intervals is crucial for protecting both the conduit and the wiring from physical and thermal issues that may arise over time, such as expansion and contraction due to temperature changes or accidental impact. This not only upholds safety standards but also enhances the longevity of the installation.

While other intervals for fastening may be relevant for different types of conduits or specific applications, the 10-foot requirement for EMT is the standard to provide the necessary balance between security and accessibility.