Instrumentation cable buyer in Charleston, SC
Instrument cable from the process plants around Charleston arrives as shielded pairs and triads, cut at a marshalling cabinet and tagged with a loop number that may matter more than the copper.
- Charleston County
- Shielded pairs and triads
- Loop and marshalling pulls
Instrumentation cable in Charleston
An instrument loop is a small circuit with a large paper trail. A shielded twisted pair runs from a transmitter in the field to a marshalling cabinet, then on to the control system. It carries milliamps, not amps. The cable is usually 18 or 16 AWG, individually shielded with a drain wire, sometimes with an overall shield as well. Thermocouple extension and RTD cable run beside it and look almost identical on a reel.
That similarity is the first problem in a review. Two reels of grey jacketed cable, same diameter, same look, one worth reviewing as instrumentation and one as control. The print settles it, and the print is often the first thing to fade. After that, the tag, the loop sheet and the plant’s cable schedule do the work. Without any of the three, it is a shielded cable lot and gets described as one.
The material lives in electrical rooms, not in laydown yards. In the process plants up the Cooper toward Moncks Corner, instrument cable is pulled, terminated, and the offcut coiled and hung on a hook or dropped in a bin beside the marshalling cabinet. When a loop is re-instrumented the old home run comes back in one piece with the shield cut at the gland. That is the shape of it here: short, clean, tagged.
Around the port and the rail-served sites the picture is different again. Warehouses and terminals hold control and signal cable from conveyor and weighing systems, usually on a partial reel with a contractor’s barcode. It sits next to tray cable and looks like it. The plants separate their cable by system because their drawings demand it. The warehouse usually does not, and that is where the sorting starts.
Why this material gets reviewed properly
The loop sheet is the manifest
A plant that keeps loop drawings can say what every coil is, what it connected and roughly how long the run was. That turns a pile of shielded cable into a schedule. A seller who can hand over a cable schedule, even a marked up one, gets a review that starts at the loop rather than at the jacket. Without it we are reading print.
Shields do not survive careless coiling
A drain wire bent back and taped to the jacket is fine. A coil wound tight around a hand, with the shield crushed at every turn, is not, and a damaged shield changes what the cable can be used for. We look at the first few feet and the last few feet. If both are sound the middle usually is too.
Short lengths are normal, not a defect
Most instrumentation offcuts are under a hundred feet and many are under forty. That is what a loop pull leaves behind. We price them as a group, by gauge and shield type, rather than pretending each coil is a reel. A seller expecting reel pricing for a bucket of forty foot tails will be disappointed, and it is better to say that early.
Related wire types
Questions on this material
Do you take instrument cable without the loop numbers?
Yes, but it is reviewed as unidentified shielded cable rather than as an instrument loop. Gauge, shield type and conductor count can usually be read from the print or measured at the cut end. What cannot be recovered is what it was connected to. If the plant has a cable schedule, a photograph of the relevant page helps more than the tags do.
What is a triad, and how do I tell it from a pair?
Count the insulated conductors inside the shield. A pair has two, a triad has three, a quad has four. Triads are common on resistance temperature detector circuits, where the third conductor compensates for lead resistance. From outside a reel the difference is invisible, which is why the print or a look at the cut end matters.
Is thermocouple extension cable part of this?
It can be, but it is a different animal. Thermocouple extension wire is two conductors of specific alloys, colour coded by type, with a polarity that matters. It is reviewed separately from copper instrument cable because it is not copper and is not priced as copper. A photograph of the colour code and the print tells us what type it is.
Can cable be collected from a plant electrical room?
Usually it is staged first. Electrical rooms are restricted, and moving cable out of one is a housekeeping task the plant prefers to control. We ask for the material to be consolidated at a storehouse or laydown area with vehicle access, and we work to the site’s escort and clearance rules rather than around them.
Send instrumentation cable details
Pickup is in Charleston. Include condition, footage and how the material is stored.
Or email saleselectricalbuyers@gmail.com
- No fee and no obligation to sell.
- Written lot terms before anything moves.
- Pickup scheduled around your access rules.