In Episode 15 of No Dumb Questions, we explain the critical importance of temperature ratings in custom cable design and how thermal extremes dictate material selection.
Temperature ratings determine which specific conductors (such as bare, tinned, or silver-plated copper) and insulation materials (such as PVC, TPE, or silicone rubber) can be safely utilized to ensure a cable performs reliably in its intended environment.
Operating a cable outside of its designated temperature range poses significant performance and safety risks. In high-temperature conditions, such as running a 105°C-rated cable at 120°C, the insulation can degrade, melt, or deform. This causes electrical issues like altered resistance, short circuits, and severe safety hazards where users could be exposed to live electricity. Conversely, in extreme cold environments, standard materials can become brittle and crack, leading to a complete loss of insulation integrity.
Agencies like UL provide established safety ratings for high-temperature limits (e.g., 105°C, 150°C) to guide safe usage. By identifying the exact high and low temperature requirements upfront, engineers can select the precise materials needed to prevent premature failure and ensure optimal, safe operation.
Key Technical Takeaways
- Material Selection: Temperature ranges directly dictate the choice of both the conductor type and the polymer insulation (e.g., PVC vs. Silicone).
- High-Temperature Risks: Exceeding the thermal rating causes insulation to melt or degrade, leading to short circuits and dangerous exposure to live current.
- Low-Temperature Risks: Operating below a material’s cold limit causes the jacket and insulation to become brittle and crack, destroying its protective properties.
- Safety Standards: Organizations like UL provide strict high-temperature safety ratings (such as 105°C or 150°C) to ensure reliability.
- Design Phase: Defining thermal limits early in the design process is essential to prevent premature mechanical and electrical failure in the field.
Another great video! –> Episode 16: What is meant by “lay direction”?
Episode 15 Transcript – Why is Temperature Rating So Important?
Welcome to No Dumb Questions
Welcome to the next iteration of there are No Dumb Questions. Today’s question comes to us from LinkedIn. Mr. Jeffrey Parker says, what’s the importance of temperature ratings when designing a custom cable?
Material Integrity and Temperature Limits
Well, Jeffrey, that’s a great question. The reason the temperature range being called out when we’re designing a cable—helps us to pick the correct materials. So we know that that cable can safely perform in that temperature range, both high and low, and operate properly without having any issues.
So what issues could that be? Material integrity. You know, every cable is made up of tin copper, bare copper, silver-plated copper all having their own temperature ratings along with the insulation material—could be PVC, urethanes, TPEs, silicone rubbers—again all having high and low temperature ranges where they best perform.
Risks of High-Temperature Exposure
If we don’t use the correct material, you could have a performance issue or a reliability issue. If you’re using something that is rated for 105 C and you’re trying to run at 120 C, your insulation material could degrade or it could actually fail, cause a short, which then turns into our next problem of the cable may work, but is it working safely?
So if you have insulation degradation, it melts, it deforms. It’s not only going to affect your electricals, your resistance could change. But you could have a short. And then you’re having a safety concern where somebody handling the cable could actually come in contact with electricity, where they should not.
UL Ratings and Low-Temperature Brittleness
Agencies like UL will give a higher temperature range. Usually they don’t provide the lower end. That’s more, on a material base, but they’ll give a safety rating of 105 C, 150 C, and that cable can safely operate in that temperature without having issues. If you work outside those temperatures, you are at risk of having a premature failure or, again, a safety concern.
When working with lower temps, you may have a cable that is going to be used say for a ground strap cable for a power company solely for doing testing. But if it’s cold, you may have a cable that becomes brittle and may even crack. So then you have no insulation and again that becomes a safety issue.
Summary
So in summary, temperature rating, if we know it up front, we are going to design you the correct cable with the correct materials to make sure that we give you the exact product that you need. And again, Jeffrey, thanks for a great question. If you have any other questions, feel free to reach out. We’ll see you next time on there are No Dumb Questions. Thank you.