A Structured Approach to Raw Cable Selection
Selecting raw cable involves the same disciplined evaluation as selecting a connector — get the electrical, mechanical, and environmental requirements wrong, and the cable will fail in the field regardless of how well the rest of the system is designed. A structured selection process avoids over-specifying (adding unnecessary cost) or under-specifying (risking field failures).
Step 1: Define Electrical Requirements
Conductor Gauge and Current Rating
Determine the maximum continuous current the cable must carry and select conductor gauge (AWG) accordingly, leaving margin for any expected ambient temperature during operation — a cable rated at room temperature may need a heavier gauge if it will operate in a hot enclosure.
Voltage Rating and Insulation
Insulation material and thickness must be rated for the maximum voltage the cable will carry, with appropriate margin for transient spikes in switching applications.
Signal Integrity Needs
For data or high-frequency signal cable, evaluate whether the application needs controlled impedance (coaxial or twisted-pair construction), and whether shielding is required to prevent EMI ingress or emission.
Step 2: Evaluate Environmental Exposure
- Temperature range: confirm the insulation and jacket material tolerate the full expected operating range, including any transient extremes.
- Chemical exposure: identify any oils, fuels, solvents, or cleaning chemicals the cable will contact, and select jacket materials resistant to that specific exposure.
- Flex requirements: static installations can use standard stranded or solid conductors; continuously flexing applications need finely stranded, flex-rated conductors to avoid fatigue cracking.
- UV and outdoor exposure: outdoor-rated jackets resist UV degradation that would embrittle standard indoor-rated cable over time.
Step 3: Determine Shielding Requirements
Shielding protects signal integrity from external electromagnetic interference and, in some cases, protects nearby sensitive equipment from the cable's own emissions. Foil shielding offers good high-frequency coverage at low cost; braided shielding offers better mechanical durability and lower-frequency shielding effectiveness; combination foil-and-braid constructions offer the broadest protection for demanding signal integrity applications.
Step 4: Confirm Certification and Compliance Needs
Depending on the application and market, raw cable may need to meet specific standards — UL listing for North American installations, RoHS compliance for restricted-substance requirements, or industry-specific standards such as ICEA or AEIC for power cable, and VG96912 or similar military specifications for defense applications.
Step 5: Confirm Minimum Order Quantities and Lead Time
Raw cable is often available starting from small put-up quantities (some suppliers offer reels starting at a single meter for prototyping), but production volumes may require longer lead times depending on conductor and jacket material availability. Confirming minimum order quantities and lead time early avoids schedule surprises later in a program.