SELL SURPLUS CONTROL AND INSTRUMENTATION CABLE

Control cable carries switching and status signals between panels, starters and field devices. Instrumentation cable carries low-level analogue signals from sensors, transmitters and temperature elements. Both are multiconductor assemblies, both are made shielded or unshielded, and both are commonly rated 600V for control work. Instrumentation cable is normally built in twisted pairs so noise cancels along the run, and thermocouple extension wire and RTD cable are separate products with their own conductor alloys and colour codes.

Surplus here is almost always a partial reel. A control pull takes 400 ft from a 1,000 ft reel and the balance goes on a shelf in the shop or the instrument crib. Loop changes, panel rebuilds, and instrumentation packages that were cancelled after the cable was released leave reels that were never unwrapped. Because these constructions cost far more per foot than building wire, a part reel is often worth recovering.

What we buy

• 600V control cable — multiconductor, PVC/nylon or XLPE insulated, shielded or unshielded, tray-rated where marked.
• Instrumentation cable — twisted pairs with individual or overall shields and drain wires, across the usual pair counts.
• Thermocouple extension wire — types J, K, T and E with matching alloy conductors and the standard colour code.
• RTD cable — three-wire and four-wire constructions for resistance temperature detectors.
• Armored and tray-rated control — interlocked armor, or a TC or PLTC marking that permits tray routing.
• Pair and conductor counts — from two pairs upward, plus three-conductor and higher control assemblies used in panel wiring.

How to read a control cable reel

Control and instrumentation cable is the one family where the tag matters as much as the print, because the print is short and the differences between products are in the construction rather than the jacket legend. Open one end and look at how the conductors are laid.

Condition and length

Signal cable is small and light, so it survives storage well. The things that spoil it are handling damage at the ends, moisture in an open wrap, and losing the identity of the reel. A 500 ft part reel with no tag and no readable print is close to unusable, because the pair count and shield arrangement cannot be guessed from the outside.

• Part reels with the tag still wired to the flange
• Sealed cartons of multi-pair instrument cable from panel builds
• Thermocouple extension wire with the type letter legible
• Shielded control cable in 3 to 12 conductor constructions
• Mixed reels from a completed or cancelled instrumentation package

We decline loose coils with no identification, cable whose shield and drain have been cut back at both ends, wet reels with the wrap open to the weather, and single short tails. Thermocouple wire of unknown type is also declined, because the alloy cannot be confirmed by eye and a wrong match is worse than no cable.

What to photograph

1. The reel or carton label, flat and in focus, since it carries the pair count.
2. The jacket print, showing voltage and any tray or armor marking.
3. The cut end, spread slightly, so pairs and shields can be counted.
4. Any colour-coded thermocouple conductors, with the code visible.
5. The shelf or crib where the reels have been stored.

Control cable surplus in Washington, DC and Maryland

In the District, control cable surplus comes from building systems work: mechanical plant replacements, laboratory and research fit-outs, and building automation upgrades in large institutional buildings. Runs are short and pair counts are modest, so the surplus usually arrives as a handful of part reels rather than pallets.

Maryland holds the process side. Wastewater and water treatment plants around Baltimore and Annapolis, life-science facilities along the I-270 corridor, and food processing plants on the Eastern Shore all run instrument loops and keep spare reels in a crib. A plant upgrade or a control system migration typically frees multi-pair and thermocouple reels at the same time, often with the original purchase labels still attached.

Related signal and power cable

• Tray cable, TC & PLTC
• Communication & low-voltage cable
• VFD & drive cable