Add cores with the colour buttons or type them in order: brown black grey blue green-yellow, BN BK GY BU GNYE, L1 L2 L3 N PE, DC + −. Below, an offered cable can be checked against the one wanted.
By the colours and the order of the cores alone: the cable type, cross-section and voltage rating are checked separately.
Decode the cable type from the sheath marking with the marine cable designation reader, and the conductor size with the AWG to mm² converter.
Insulated conductors are identified by colour to IEC 60445: brown, black and grey are the line conductors L1, L2, L3, blue is the neutral (N), and green-and-yellow is the protective conductor (PE) and nothing else; in a DC circuit brown is L+, grey L− and blue M. Enter the core colours in order, or their functions, and the reader draws the cable with its cores, names the function of each colour, warns where a former or national scheme gives a colour a different meaning, checks an offered cable against the one wanted and writes an RFQ line.
The former UK colours (red, yellow, blue with a black neutral) and US practice are shown apart and labelled as such. A colour says what a core should be, not what it is: before work, an electrician identifies the cores by testing and proves them dead. The ship’s electrical drawings have the last word.
Brown, black and grey are the line conductors L1, L2, L3, blue the neutral (N), green-and-yellow the protective conductor (PE) and nothing else. In a single-phase circuit the line conductor is brown and the neutral blue. DC: L+ brown, L− grey, M blue.
In the UK before 2004–2006 the phases were red, yellow and blue and the neutral black. In US practice the neutral is white or grey and the equipment grounding conductor green, green with yellow stripes or bare. Black and blue mean different things in different schemes, and the reader warns where they do.
On ships, the cores of multicore cables often carry printed numbers: IEC 60092-376, for control and instrumentation cables on ships, has an annex on marking the cores of multicore cables. A colour or a number says what a core should be; before work, an electrician identifies the cores by testing and proves them dead.
| Colour | Code | IEC 60445, AC | IEC 60445, DC | Former UK colours | US practice (NEC) |
|---|---|---|---|---|---|
| Brown | BN | L1, line | L+, positive | — | phase, customary at 277/480 V |
| Black | BK | L2, line | — | N, neutral | phase, customary at 120/208 V |
| Grey | GY | L3, line | L−, negative | — | neutral (grounded conductor) |
| Blue | BU | N, neutral | M, mid-point or earthed pole | L3, line | phase, customary at 120/208 V |
| Green-and-yellow | GNYE | PE, protective | PE, protective | PE, protective | equipment grounding |
| Red | RD | — | — | L1, line | phase, customary at 120/208 V |
| Yellow | YE | — | — | L2, line | phase, customary at 277/480 V |
| White | WH | — | — | — | neutral (grounded conductor) |
| Orange | OG | — | — | — | phase, customary at 277/480 V |
| Green | GN | — | — | — | equipment grounding |
Every assignment here is confirmed by two independent sources. Brown, black and grey are shown as L1, L2, L3 in the order national rules give (UK, Hong Kong); whether IEC 60445 itself fixes that order could not be confirmed. Left out for want of two agreeing sources: the marking of a PEN conductor, the UK functional earth colour, the former UK DC colours, Canadian colours, the US high-leg colour, the colour order of the cores of multicore cables and any classification society rule on numbered cores. One summary gives blue for DC negative; in the two agreeing sources blue is the earthed pole M, which in a negative-earthed circuit is the negative, and it is shown that way.
The Hong Kong Electrical and Mechanical Services Department (EMSD) page on the new cable colour code; a device maker’s guide to IEC wiring colours; Wikipedia on electrical wiring in the United Kingdom and in North America; the Voltimum harmonised cable colours FAQ; the NBS article on the colour coding of low voltage fixed wiring cable cores; the IET Wiring Matters history of colour identification of conductors; a cable maker’s page on HD 308 S2; EC&M on colour coding under the NEC; the contents of IEC 60092-376:2025 and marine cable datasheets with numbered cores. Every assignment is in at least two of them.
Brown for L1, black for L2, grey for L3, blue for the neutral (N) and green-and-yellow for the protective conductor (PE). In a single-phase circuit the line conductor is brown and the neutral blue. Green-and-yellow is kept for the protective conductor only.
Before the harmonised colours, UK fixed wiring used red, yellow and blue for the three phases and black for the neutral, and single-phase circuits red and black. The new colours were allowed from 31 March 2004 and required for new work from April 2006. In a mixed installation black and blue swap roles, so the cores are marked where old and new wiring meet.
Under IEC 60445 the positive conductor L+ is brown, the negative L− grey and the mid-point conductor M blue. In a two-wire circuit with one pole earthed, the earthed pole is blue. The protective conductor stays green-and-yellow.
Under the NEC the neutral (grounded conductor) is white or grey and the equipment grounding conductor green, green with yellow stripes or bare. The NEC does not fix the phase colours; black, red and blue at 120/208 V and brown, orange and yellow at 277/480 V are customary.
The type marking printed on the sheath, the number of cores and their colours in order, or the numbers printed on them, the cross-section in mm², the voltage rating and the length in metres. On ships the cores of multicore cables often carry printed numbers, so give the numbers as printed.
The decoding is a colour reference, not a test of the ship’s wiring. Attach a photograph of the cable end and the sheath marking, and Vessel Core checks them before an offer goes back.
