Jan. 10, 2026
A screened control cable is the single product choice that prevents a surprisingly large share of electrical headaches on a modern plant floor. This article explains what a screened control cable is, why engineers specify screened runs, which construction choices matter most, how to write an RFQ that returns apples-to-apples quotes, and what installers must do on site to preserve the cable’s engineered performance. Read this if you need fewer nuisance trips, faster commissioning, and lower lifecycle cost from your control wiring.
(The product name “screened control cable” appears naturally throughout this article.)
When you order a screened control cable you’re asking for a multicore control or signal cable with an electrically conductive layer around the cores to intercept external electromagnetic interference (EMI). The screen can be foil, braid, or a combination; in many catalogues you’ll see LiYCY, LiYCY(TP) or similar designations describing the same idea: individually insulated cores, overall screening, and an outer jacket. The purpose is simple — keep noise out of the control signals so PLCs, encoders and sensors behave predictably.
(Reference product families and well-documented datasheets for such constructions are widely published by cable houses.)
Industrial facilities are awash in noise sources: variable frequency drives, welders, large motors, switching supplies and nearby power feeders. Unscreened control cabling sometimes works for a while and then fails intermittently once machines are added or routing changes. A correctly specified screened control cable prevents induced voltages and reduces false trips, spurious inputs, and data errors — the sort of intermittent faults that eat weeks of commissioning time and maintenance hours.
Not all screens are the same. The common options are:
Foil screen: thin, continuous foil (often aluminum/polyester) that gives excellent high-frequency immunity and keeps pairs tight. Good for high-frequency noise and twisted-pair designs.
Braid screen: tinned copper braid offering mechanical protection plus superior low-frequency rejection; braid coverage is expressed as a percentage and higher coverage improves immunity.
Foil + braid: combined construction that protects across the spectrum and survives mechanical stress.
Choosing the right screened control cable construction depends on the dominant noise type and the mechanical demands of your installation. For mixed environments a foil+braid screened control cable is a common, pragmatic choice.
A screened control cable can be used inside panels, across machine frames, or in moving applications. The conductor build is the key differentiator:
For static wiring and fixed panel interconnects, coarser strand classes are acceptable and cost-efficient.
For frequent flexing, cable carriers or pendant drops, choose a flex-rated screened control cable with fine-stranded (Class 5 or higher) conductors to avoid strand fatigue and early failures.
Always insist on the published strand count and flex class in supplier datasheets — that number predicts real field life far better than a cosmetic photo.
The outer jacket protects the screened control cable from oils, chemicals, sunlight and mechanical abrasion. Choose jacket chemistry to match duty:
PVC — general purpose, economical for indoor dry environments.
LSZH / FRNC — low smoke, zero halogen for plenum and escape-route spaces.
Oil-resistant elastomers — for factory floors exposed to lubricants and coolants.
UV stabilized compounds — for exposed outdoor runs.
Specifying the correct jacket at the RFQ stage prevents costly mid-life replacements.
To get apples-to-apples responses from vendors, include these mandatory fields in every RFQ for a screened control cable:
conductor count and cross-section (AWG or mm²) and strand class,
screening type (foil / braid / foil+braid) and braid coverage (%),
presence and spec of drain conductor,
insulation material and thickness, jacket compound and rated temperature,
voltage rating and approvals (e.g., IEC, VDE, UL),
minimum bend radius and flex rating (if motion expected), and
packaging (cut lengths, coils, spools) and sample policy.
Vendors who return full datasheets, DCR figures and braid coverage save you time and reduce procurement risk. The screened control cable you buy should match these RFQ numbers exactly.
A screen only helps if it’s terminated correctly. Installers commonly make these mistakes: leaving shields floating at both ends, over-stripping the screen, or creating poor mechanical bonds. Best practice for a screened control cable termination:
expose the screen only where you will make the connection, fold it back neatly, and attach a properly crimped drain lug;
bond the screen to protective earth at the recommended single point (follow the controller/manufacturer guidance to avoid ground loops);
use ferrules on stranded conductors and torque screw terminals to the specified value.
Done right, the screen behaves as intended. Done badly, the screen can make interference worse. Practical termination notes are some of the most valuable technical assets vendors can supply.
Good routing practices are simple and effective:
separate screened control cable runs from high-power feeders (or cross at right angles),
avoid tight bundles with power or welding leads,
respect minimum bend radius when pulling through trays and ducts, and
secure strain reliefs at cabinet entry points to avoid movement at lugs.
Following these rules preserves the screen’s function and prevents mechanical damage to insulation and braid.
Before final sign-off, test each screened control cable run for continuity and insulation resistance, and verify shield continuity. For critical long runs perform a loaded voltage-drop check on power cores and a signal integrity test on data/sensor pairs. Require test certificates for large lots so you can trace issues back to production batches if necessary.
For multi-pair screened control cable builds you can have individually screened pairs (pair screens) plus an overall screen. This construction is common where adjacent pairs carry different signals and crosstalk must be minimized. If your design includes mixed signal types or long serial links, insist on pair screening in your screened control cable specification.
Consider adding:
tinned braid for corrosive or marine environments,
numbered cores or printed sequential markings for rapid fault tracing, and
spare pairs for future expansions.
These small features improve maintainability and reduce retrofit time — cheap insurance on a capital project.
A screened control cable with a modest premium often reduces troubleshooting, shortens commissioning, and lowers total cost of ownership. Evaluate installed cost over expected life, not just the per-metre price. For mission-critical lines, insist on samples and short flex tests before bulk buys.
Treat the screened control cable purchase like an engineering step: define the duty (static, occasional flex, continuous motion), demand detailed strand and screen numbers, match jacket chemistry to the environment, require sample acceptance tests for mission-critical orders, and document termination and routing rules for the installation team. Do this once and your screened control cable runs will be quiet, dependable infrastructure rather than recurring maintenance problems.
Next chapter:
What a 4 core control cable is used for
