Tightening an EMT compression coupling involves securing the conduit within the coupling body to create a robust and often sealed connection. This type of fitting works by compressing a ring or gasket onto the conduit.
Understanding EMT Compression Couplings
EMT (Electrical Metallic Tubing) compression couplings are commonly used to join two sections of EMT conduit or to connect EMT to electrical boxes or enclosures. Unlike set-screw fittings, compression couplings provide a strong mechanical connection and can offer protection against environmental factors like rain, as indicated by the "Rain Tight" designation on some models. The tightening process is key to achieving both the mechanical security and the seal.
Steps to Tighten an EMT Compression Coupling
The process begins with preparing the conduit and inserting it into the coupling, followed by tightening the compression nuts.
Step 1: Insert the Conduit
The initial step is inserting the conduit properly into the coupling body.
- Action: As described in the provided reference, you take your 3/4 in EMT conduit and slide it directly in to the open side of the coupling.
- Detail: Ensure the conduit is inserted fully until it seats against any internal stop or gasket. The reference mentions the presence of a ceiling gasket on the inside, which helps create the seal when compressed.
Step 2: Tighten the Coupling Nuts
Once the conduit is inserted into both sides of the coupling, the compression nuts are tightened to secure the connection.
- Action: Use appropriate wrenches to turn the nuts on the coupling body.
- Method: Typically, you will need two wrenches. Use one wrench to hold the body of the coupling steady and use the second wrench to turn one of the large compression nuts.
- Process: Tighten one nut until it feels snug, then repeat the process on the nut for the other side of the coupling.
- Compression: As you tighten the nuts, they push against a component inside the coupling (often a gland ring or ferrule and the gasket), compressing it onto the surface of the EMT conduit. This compression is what secures the conduit and creates the seal.
- Final Tightening: Alternate tightening the nuts on each side, ensuring even pressure. Tighten them firmly to achieve a secure mechanical connection and a proper seal, especially if a "Rain Tight" connection is required. Avoid overtightening, which could damage the coupling or the conduit.
Why Proper Tightening is Crucial
Correctly tightening an EMT compression coupling is essential for several reasons:
- Mechanical Strength: It ensures the coupling firmly grips the conduit, preventing it from pulling out.
- Electrical Continuity: A tight connection helps maintain proper grounding continuity through the conduit system.
- Environmental Seal: For fittings like the "Rain Tight" type mentioned, proper compression of the internal gasket creates a seal against water and dust, protecting the wiring inside.
By following these steps, including the initial insertion described in the reference and the subsequent tightening of the compression nuts, you can successfully install an EMT compression coupling.
