Okay, joining 2" Rigid Metal Conduit (RMC) to 2" Schedule 80 PVC pipe without threading the RMC in a remote location presents a few challenges. Here's a breakdown of the best options, considering factors like reliability, availability, and ease of implementation given your constraints

Best Option (Most Reliable and Code-Compliant)
RMC Coupling to a PVC Adapter

This is generally the most reliable and preferred method, especially when grounding is a concern.1.

RMC Coupling (Set-Screw or Compression)

Use a 2" RMC coupling designed for joining RMC. Set-screw couplings are typically easier to install in the field without specialized tools compared to compression couplings (which may require a wrench for proper torque).2.

RMC to Female PVC Adapter

This adapter has a threaded end that screws into the RMC coupling and a smooth socket end to which you can glue your PVC pipe. It is a metal threaded fitting with a PVC socket end designed for this purpose.3.

PVC Cement

Use the correct PVC cement for Schedule 80 PVC.

Installation Steps

Slide the RMC coupling onto the end of the RMC pipe. Tighten the set screws securely, or tighten the compression ring (if using a compression coupling). Thread the RMC to PVC adapter into the open end of the RMC coupling. Clean the inside of the PVC adapter socket and the outside of the PVC pipe end with PVC cleaner/primer. Apply PVC cement liberally to both surfaces and quickly insert the PVC pipe into the adapter socket. Twist slightly as you insert. Hold firmly for the recommended time (as per the cement instructions) to allow the joint to cure.

Pros

Strong, reliable connection. Provides grounding continuity (through the metal RMC coupling). Code-compliant in most jurisdictions. Uses readily available parts. Relatively easy to install with basic tools (screwdriver/wrench).

Cons

Requires purchasing specific adapters. RMC couplings, especially set-screw types, must be properly tightened to ensure a secure connection and maintain grounding.

Other Options (With Considerations) Mechanical Coupling (e.g., Gruvlok or Similar)

These are designed to join different types of pipe without threading or welding. They consist of a grooved fitting and a gasket/seal. You would need a special tool to groove the RMC pipe.

Pros

Can join dissimilar materials; doesn't require threading.

Cons

Requires the correct size and type for your application. Grooving tools can be heavy and require power. The reliability of grounding needs to be verified (often requires grounding straps). May be more expensive and harder to source in a remote location.

Direct Burial Rated Heat Shrink

There exist direct burial rated heat shrink products designed for sealing and protecting underground splices and connections. These are thicker than standard heat shrink and provide a waterproof seal.

Pros

Can provide a waterproof seal.

Cons

Not ideal for a rigid mechanical connection.

Note

If you use heat shrink, you still need to bridge the physical gap. Consider using the internal sleeve of an RMC coupling, or a short piece of PVC pipe, to span the connection and provide mechanical strength before applying the heat shrink.

Important Considerations for Your Remote Location



Weight and Portability

Prioritize the lightest and most compact solutions to minimize transport costs and effort. RMC couplings and adapters are relatively small and lightweight.

Tool Requirements

Choose a method that requires minimal specialized tools. Set-screw RMC couplings only need a screwdriver.

Availability of Supplies

Check with local suppliers or hardware stores on the island before you commit to a solution. Make sure you can actually obtain the necessary parts. Order in advance if needed.

Corrosion Resistance

Consider the environment (saltwater, humidity, etc.). Use corrosion-resistant materials or coatings if necessary.

Grounding

Critical. If the RMC is used for grounding, you must maintain grounding continuity across the joint. The RMC coupling and adapter method provides the best path. If using a non-conductive method, use a suitable grounding clamp and bonding jumper to connect the RMC and PVC.

Code Compliance

Check local electrical codes and regulations to ensure your solution is compliant. The coupling and adapter method is generally the most likely to meet code requirements.*

Strain Relief

Support the piping on both sides of the joint to minimize stress on the connection. This is especially important if there is any movement or vibration.

Recommendation

Start by sourcing the

RMC coupling and PVC adapter locally. If they are available, this is the preferred method due to its reliability, grounding capability, and relative ease of installation. If these are not available, the mechanical coupling can be a potential choice but verify availability and that you have the correct tool.Before you start the job, plan your process well, gather all the necessary materials and tools, and consider a trial run if possible. Good luck! Flag for review