There are times where medical cable designs requiring super flexible wire and the available UL styles don't match the design requirements. This happens often. UL sets the standards for different categories of wire and cable. The standards include wall thickness, material, voltage rating, flammability, type of conductor and other factors. What these standards do not take into account are the requirements for individual medical devices for ultra flexible wire or cable, high flex wire applications and sterilization techniques. Custom wire and cable manufacturers can manufacture the same construction to meet the UL specification while making improvements on performance for example using higher strand conductors, alloys for added flexibility and strength or insulation and jacket material improvements.
Recently, we received design request for a flexible flat medical wire for a two conductor cable with multiple lumen, the customer required a UL style for the wires but not the lumen. We often receive requests for medical cable designs requiring UL certified conductors but not all the components in the cable.
The reality is that UL certification for individual components becomes null and void when used in medical devices. If the device needs to be UL certified then the entire device needs certification not just the components individually. Custom cables can be manufactured to perform better than a UL cable. Some examples of improvements are:
More flexible construction and materials
Withstand sterilization and chemicals
Hi-Flex and vibration resistant
Conductor sizes outside the UL style
There are many UL styles for wire available and finding a close match to your needs is possible however, finding a close match is not the same as having a cable to meet or exceed your requirements. Wire can be designed to meet voltage, flame and other requirements and doesn't have to be UL certified to do so. When designing your wire and cable it is important to look at your individual product requirements and design the wire to meet those needs.
If your medical device is required to be UL certified, then design the wire and cable to meet your product's needs instead of designing your device around available UL styles. In the end the entire device will need to be certified.