In the transit industry, cables face especially harsh conditions. While enduring extreme temperatures ranging from sub-zero to well over 150 degrees Fahrenheit, these cables are also prone to getting crushed, eroded, and bent during day-to-day operations. But most dangerously, cables could contribute to fire spread or generate toxic smoke if they aren’t properly tested and certified before use.
For procurement managers sourcing these materials, verifying the claims made by suppliers is essential risk management. If a non-compliant cable is found while a rail system is tested during final inspection, the project could be stalled for months and rack up retrofit costs that will likely exceed six figures.
Cameron Connect’s Exrad cable meets all compliance specs, but we want to demonstrate just how important this matter is.
Knowing what to look for when evaluating vendors and suppliers is key to finding the right cables for a railway system. After all, buying cables that “meet requirements” is much different from purchasing ones that have been tested and documented to meet AAR S-501 requirements using RP-585 test methods.
What Is AAR S-501?
Focusing on ensuring the durability, safety, and reliability of cables across a wide range of factors, AAR S-501 compliance looks for the following during compliance testing:
Conductor material: The conductor, or the metallic core that carries electricity through the cable, must be composed of soft annealed copper, tinned or lead alloy coated, and stranded according to the standard’s charts.
Insulation: cables must have a protective coating or insulation to prevent electrical leakage and shock. Think high-performance, cross-linked insulation materials such as XLPO.
Voltage ratings: cables with different voltage ratings must have corresponding minimum insulation thickness.
Temperature range: Temperature performance is validated through RP-585 testing, including cold bend at –55°C and cold shock at –40°C, plus thermal aging and heat resistance tests up to 158–175°C, with dielectric withstand requirements after exposure.
Environmental resistance: cables must resist common environmental hazards in a rail setting, including caustic cleaning solutions, crushing forces, fungus growth, and oil.
What Is RP-585?
While AAR S-501 establishes what cables must maintain, RP-585 defines how those claims are verified through testing. Understanding what these cables can withstand is essential, but grasping how they’re tested and certified is equally as important. The verification process consists of four main parts:
Flame retardance: cables are exposed to a controlled flame source to determine if their maximum flame retardance and toxicity characteristics meet broader fire safety standards.
Mechanical strength: cables, both new and aged, are stretched to test their tensile strength over time.
Electrical performance: cables endure voltage withstand tests, also known as electrical safety evaluations, to ensure they meet specific insulation values.
Cold performance: cables are put through “cold bend” tests at temperatures as low as -67 degrees and -40 degrees Fahrenheit to ensure they don’t crack below freezing.
Understanding what these standards mean and how they’re tested is one thing. Making sure your cable supplier meets them is another.
Verifying Supplier Claims
For cables, “meets requirements” is a far cry from being tested and certified. While a cable can technically meet design requirements, it can fail miserably when put to the test. Take a cable that meets the AARS-501 insulation requirements, for example. It could technically be thick enough to be compliant, but what if it’s made from inferior materials that crack in frigid temperatures? Not good.
However, that won’t stop some cable suppliers from trying to make a sale anyway. They could claim their cables meet S-501 requirements, but self certification does not equate to having an accredited third party putting cables through the S-501 test.
Installing non-compliant cables can have catastrophic consequences. Removing and replacing each cable would be time-consuming, expensive, and inconvenient. But moving forward with the project without tested and certified cables may result in cascading system failures, loss of operating certifications, and safety risks that could have been avoided.
But rest assured, an ISO-accredited third-party test laboratory will provide documentation that a proper AAR S-501 test was conducted.
Questions to Ask During the Procurement Process
Knowing the right questions to ask can reveal warning signs during supplier conversations. Procurement managers should ask about the following to ensure the cables meet their specific needs: quality, supplier evaluations, cost considerations, safety, and technical applications.
Here’s a sample question for each of these categories:
Quality: Can you provide third-party testing reports showing your cables have been tested to meet AAR S-501 standards?
Supplier evaluations: What is your typical lead time from order to delivery?
Cost considerations: What payment terms do you offer, and do you charge extra for order cancellations or modifications?
Safety: What temperatures have you tested your cables at? Can you provide that test data?
Technical applications: How long would your cables last in our operating environment? What factors would shorten their lifespan?
If a supplier can’t answer some of these questions or verify that their cables have been tested and certified by a third party, it would be smart to go with a different vendor who can provide adequate documentation.
Once a procurement manager finds a supplier that confidently answers questions in all of these categories, they can move forward with the cable installation with peace of mind. But most importantly, they will finish their railway project on time, on budget, and with quality materials that are certifiably safe and up to AAR S-501 standards.












