Control cable buyers in New York

Numbered or color-coded, and why it matters

Two conventions dominate. Color-coded cable assigns a distinct color to each core — black, white, red, green, orange, blue, brown, violet — and repeats them with tracers on longer counts. Numbered cable makes every core black and prints a number on the insulation, which is the standard from about seven conductors upward and is what most plants specify for motor control centers, relay panels and substation control houses.

Numbering is not a cosmetic detail. An electrician terminating a 19-conductor cable in a panel needs to identify a core at both ends without ringing it out, and printed numbers make that immediate. Color-coded cable at high conductor counts depends on tracer combinations that are slower to read and easier to misread under plant lighting.

For a seller this changes what a reel is good for. A 12-conductor numbered cable can go into almost any plant. The same size in a color code that does not match the buyer's standard may only suit a project that is already specified around it. State which convention the cable uses, and photograph the core lay at a cut end so it can be seen rather than described.

Shielded, unshielded, tray and conduit

Most 600 V control cable is unshielded and lives in conduit, in cable tray or in a wireway. A shield is added when the circuit is sensitive or when it runs near drives, rectifiers, welders or radio equipment. The usual shield is aluminum-polyester foil with a tinned copper drain wire; a copper braid is used where mechanical robustness or high-frequency performance matters. Shielded control cable has to be grounded deliberately, normally at one end, and the drain wire has to be terminated properly or the shield does nothing.

Tray rating decides a large part of the market. Type TC to UL 1277 is listed for use in cable trays, and TC-ER adds the ability to run exposed between the tray and the equipment without a raceway. PLTC to UL 13 is a lighter construction for Class 2 and Class 3 circuits, common on instrumentation and low-energy control. A reel printed only as 'control cable', with no TC, TC-ER or PLTC designation, may not be acceptable in tray at all, and a buyer will price it as conduit-only material.

Sunlight resistance, oil resistance and direct-burial ratings also appear in the print. Each one removes a restriction, and each one is worth confirming from the jacket rather than assumed from the color.

Where New York plants and substations use it

In a substation control house, control cable runs from relay and breaker failure panels out to the yard: trip and close circuits, status and alarm contacts, transfer trip, and the interlocking between breakers and disconnects. Conductor counts are high, shields are common, and the cable is usually specified by the utility rather than by a contractor, which means the print on the jacket often matches a standard the utility will still accept.

In a plant, control cable is the nervous system of the motor control center: starter coils, run and trip feedback, remote selector switches, conveyor interlocks, valve and damper control, boiler and chiller sequences. Food, beverage and pharmaceutical plants add washdown and sanitisation requirements; wastewater plants add corrosive atmosphere and buried runs; semiconductor and laboratory buildings add tight temperature and smoke requirements. Each of those leaves surplus on a different cycle, and each produces a recognisably different reel.

• Substation relay, breaker and transfer trip circuits
• Motor control center starters and interlock wiring
• Conveyor, packaging and process line control
• Boiler, chiller and central plant sequences
• Water and wastewater treatment control
• Building automation and equipment monitoring