Okay, let's break down the situation and address your questions.

Understanding the Wire and Code Considerations The Wire You Linked

The Polar Wire you linked appears to be suitable, but you absolutely MUST verify the markings on the actual wire received match the intended use. It's listed as having THHW, TEW, MTW, AWM, BC-5W2, SAE Type SGT-CT markings. That's a good starting point.

THHW

This is the critical part. THHW insulation is a very common and widely approved insulation type for general wiring in both wet and dry locations. This is a standard wire recognized by the NEC.

TEW/MTW/AWM/SGT-CT

These are additional ratings that indicate the wire is suitable for machine tool wiring (TEW/MTW), appliance wiring (AWM), or automotive (SGT-CT) applications. These don't inherently disqualify it for general wiring use, but they highlight the stranding is a primary difference.

BC-5W2

This designation likely refers to the conductor construction. "BC" is bare copper. The "5W2" likely indicates a specific stranding pattern for improved flexibility.

Flexibility and Bending Radius

The key reason you're considering this wire is its flexibility. THHN/THWN has solid or minimally stranded conductors, making tight bends difficult. Flexible wire, with its many finer strands, will allow for a much tighter bending radius.

Regarding Code Compliance (NEC) General Use

If the wire is clearly marked THHW, it meets the requirements for general-purpose wiring within the limitations of that insulation type. It can be used within raceways (like your FMC) as long as the other ratings don't conflict with the usage.

Ampacity

You need to ensure the wire's ampacity (current-carrying capacity) is adequate for your load and that the circuit is properly protected by an overcurrent device (breaker or fuse). The ampacity will be determined by the THHW rating and installation conditions (temperature rating of terminations, ambient temperature, number of conductors in a raceway, etc.).

Wet vs. Dry Locations

THHW is suitable for both wet and dry locations. This is important to know for where your FMC conduit runs.

Connecting Flexible Wire to Lugs

This is where proper technique and approved hardware are essential. Ferrules



Yes, ferrules are generally the BEST practice for terminating finely stranded flexible wire into screw-type or compression lugs. Here's why: Containment

Ferrules keep the fine strands of the conductor neatly bundled together, preventing them from splaying out or breaking off. This is critical for maintaining a good electrical connection.

Contact Area

Ferrules provide a solid, consistent contact area between the wire and the lug. This reduces the risk of overheating and loose connections.

Torque

Ferrules help prevent the screw of the lug from damaging the fine strands when tightened.

Ferrules and UL Listing/Manufacturer Instructions

Here's the critical part: You MUST use ferrules that are UL-listed (or otherwise approved) for use with the specific wire type and the specific lug you are using. Some lug manufacturers specify approved ferrules. Consult both the wire and lug manufacturers' documentation.

Ferrule Crimping

You must use the correct crimping tool for the ferrules you are using. This ensures a proper, gas-tight crimp. A poor crimp is as bad (or worse) than no ferrule at all.

Alternative Termination Methods



Pin Terminals

Similar to ferrules, these are solid pins that get crimped onto the wire end. They may be suitable for some lug types.

Tinning

While sometimes used in the past, tinning the wire ends with solder is

generally discouraged for modern installations, especially with screw-type lugs. The solder can creep and loosen over time, leading to a poor connection.

Important Considerations and Recommendations1. Local Electrical Inspector

Before you do anything, talk to your local electrical inspector (AHJ - Authority Having Jurisdiction). Explain your situation and the wire you plan to use. They will have the final say on whether it's acceptable and what termination methods they require. This is the MOST important step.2.

Wire Markings

Verify the markings on the actual wire you receive. Do not assume that the online listing is completely accurate.3.

Lug Compatibility

Ensure that the lugs in your panel and distribution block are rated for the wire size and conductor type (copper). Some lugs are only rated for solid or stranded wire up to a certain stranding class.4.

Proper Installation

Follow all applicable codes and best practices for wiring. This includes proper wire stripping, torqueing lugs to the specified values, and supporting the wiring adequately.5.

Consider Wire Size

For a short run like this, if the flexibility is the primary concern, you might consider upsizing to the next larger wire gauge if it will improve flexibility (e.g., go to 3/0 AWG flexible). This might make it easier to bend and terminate. However, you must ensure the lugs are rated for the larger wire size.6.

Professional Installation

If you are not completely comfortable with any aspect of this work, hire a qualified electrician. Improper wiring can be dangerous and potentially lead to fires.

In summary: The Polar Wire may* be suitable, but you must verify the markings and ratings. Using ferrules is highly recommended (and often required) for terminating finely stranded wire. Most importantly, consult with your local electrical inspector before proceeding. Flag for review