All equipment and machinery across the EU is standardised through European Commission directives, including wiring. These directives are referred to as EN (European Norm) codes and are usually formulated in compliance with standards set by the International Organization for Standardization. At Rowse, we are able to supply a wide variety of control cables for wiring your control panels and systems, but many of our customers are uncertain about the rules governing colour codes.

Wiring Colour Codes

The colour codes used in the past were originally determined by the British standard regulations BS 7671, but these standards were set down before complex automated systems were even thought of – and they largely related to domestic circuits and static installations. The EN codes supersede the old British Standards (for the time being, at least) and the international standard EN 60204-1 specifically governs Control Panel Wire Colour Codes.

EN 60204-1 (Safety of Machinery – Electrical Requirements of Machines) sets out both the required safety standards and the type and colour of cable that should be used for wiring an electrical enclosure. In addition, the International Electrical Commission has also issued a revised standard IEC 60445:2017, covering safety principles for HMI terminals, including the marking and identification of equipment terminals, conductors and conductor terminations.

CONTROL PANEL WIRING COLOUR CODES PER EN 60204-1

The choice of cable colour initially depends on what type of circuit it is, and whether the voltage is AC or DC.

AC and DC Power Circuits

AC and DC Control Circuits

Panel Services Colour Coding (multicore)

Panel Services Colour Coding (single core)

The wire used for the protective conductor (earth) must be GREEN-AND-YELLOW. This colour combination is reserved specifically for the protective earth and must be maintained throughout the wire's entire length. If the wire is insulated, the GREEN-AND-YELLOW combination must be a 70/30 distribution over the surface area on any 15mm length (this is usually produced as GREEN with a YELLOW stripe). If the wiring is installed in an inaccessible position or is clearly identifiable as the protective earth, the GREEN-AND-YELLOW colour coding can be confined to any location where the wiring is accessible or to the ends of the conductor.

The specified colour for the neutral conductor wiring is LIGHT BLUE. This colour should be restricted to the neutral wire and not used for any other associated cables, so that there is no possibility of confusion between neutral and some other function. This colour should permeate the entire length of the neutral conductor, or if the wiring is in a concealed location or somewhere with limited access, the cable can be identified with a 15-100mm LIGHT BLUE stripe.

You should use neither GREEN nor YELLOW Control Panel Wiring separately where there is any possibility of it getting confused with the combined GREEN-AND-YELLOW wire used for the protective earth.

Tri-Rated Cable

The very popular Tri-Rated Cable (rated under BS 6231) is a kind of high temperature, fire retardant cable specifically designed for control panels used in power switchgear. It is also rated for use by the standards organisations of the US and Canada, hence the 'Tri-Rated' title, and can also be called control panel wire, switchgear cable or tri-rated single (TRS) wire. Tri-Rated Cable can function at temperatures of up to 105ºC, but for safety's sake BS 6231 stipulates 90ºC as the maximum operating temperature. Conversely, the British Standard voltage rating for the cable is higher than the voltage permitted in the United States equivalent.

The advantage of the triple rating is that it can be used in a much greater range of markets, reducing design duplication and allowing for a much greater degree of flexibility in manufacturing processes. The panel wire is flexible, with a single core and one layer of heat-resistant PVC insulation. It has varied applications in many industry sectors, being used for wiring electrical cabinets, instrumentation panels or relays. It can operate inside small electrical devices, and also functions as an internal connector in things like rectifier equipment, motor starters and controllers.