2023 NFPA 70, 355 Reinforced Thermosetting Resin Conduit (RTRC)

[GetWiredEmpire]

This isn't a question; it's information.

In Reinforced Thermosetting Resin Conduit (RTRC), the "thermoset" appears to mean "reinforced fiberglass."

But I am curious about this, since I am learning about conduit. It's more than just fiberglass that goes into pipe making.

In electrical applications, reinforced thermosetting resin conduits (RTRC) are commonly used. Three types of resins used in RTRC in electrical applications are polyester resin, vinyl ester, and epoxy resin.

• Polyester Resin: Polyester resins are highly customizable and are used in the manufacture of various composite products. They are known for their excellent versatility and are suitable for use in less corrosive environments 5.
• Vinyl Ester: Vinyl ester resins are preferred for applications requiring long-term durability. They offer exceptional moisture and corrosion resistance, making them ideal for marine and coastal products such as corrosion-resistant tanks and pipes 5.
• Epoxy Resin: Epoxy resins are commonly used with high-performance reinforcements such as carbon or glass fibers. They are cured using a hardener and offer beneficial mechanical and electrical properties 4.

These resins play a crucial role in providing mechanical properties, corrosion resistance, and electrical insulation in RTRC used in electrical applications 4 5.

- Perplexity.ai thread

And I also learned about "thermoplastic" which can be re-melted.

Here are some key points of differentiation between thermosetting resins and thermoplastics:

• Behavior under heat: Thermosets strengthen when cured and form chemical bonds that make them impossible to remold, while thermoplastics do not form any chemical bond when curing, making them re-moldable and recyclable 3 5.
• Recyclability: Thermoplastics can be repeatedly melted and re-used, while thermoset resins cannot be melted without decomposition and will break into pieces if an attempt is made to melt them 4.
• Strength and heat resistance: Thermosets generally have greater physical properties than thermoplastics and can retain their strength and geometry when exposed to elevated temperatures. They will often degrade before melting when exposed to excess heat, making them suitable for high-temperature applications 5.

- Perplexity.ai thread

Learn more by visiting this article on Thermoset vs Thermoplastic (archive link).

 

[GetWiredEmpire]

Another thing about RTRC is the "-XW" designation.

355.12(C)
RTRC installed in a location where the raceway is subject to physical damage must be marked “XW.” If the location is above ground and exposed to physical damage, the conduit must be marked “AG XW RTRC.”

See also 305.15(A), 334.15(B), 501.10(B)(1)(6), and 551.80(B) for examples of requirements specifying the use of RTRC-XW.