Thermoplastic-sheathed cable
Thermoplastic-sheathed cable (TPS) consists of an outer sheath of polyvinyl chloride (PVC) insulation (the thermoplastic element), one or more inner coloured thermoplastic sheaths, and a core (or cores) of plain annealed copper (single- or multi-strand). It comes in a variety of colours and wire gauges. TPS is also often referred to as Tough Plastic Sheathed.[1][2]
The type of thermoplastic and size of the conductor(s) are covered by different regulatory bodies around the world.[3] Flat TPS is more common, and is used for fixed wiring of domestic and industrial lighting, power outlets and heating. Round TPS is less common, and is usually used where cable glands are required. It is more difficult to strip insulation from round TPS than from flat.
TPS is more vulnerable to rodent damage and accidental mechanical damage than armored cable.
In North America, this type of cable is referred to as NM cable. NM means "Non Metallic", but this refers only to the outer sheathing; hence, the designation really should have been NM-S. Type NM cable is often referred to by the trade name of "Romex"[4] in North America.