FREE DELIVERY ON ORDERS OVER £75
Electrical Tape Colours — BS 7671 Conductor Identification, PVC Insulation Tape, and Cable Core Marking for UK Electricians
Electrical tape is one of the most frequently purchased consumables on any domestic or commercial electrical job — but it is also one of the most misunderstood. UK regulations under BS 7671:2018 (Amendment 2:2022) specify exact colour codes for conductor identification, and using the wrong colour tape on a switch wire, earth sleeving, or three-phase phase bar can constitute a non-compliant installation. This guide explains the correct tape colours for UK electrical work, where each colour must be used, and how to choose the right PVC insulation tape for your application.
BS 7671 Conductor Identification Colours — Current Harmonised Colours
The UK adopted harmonised conductor colours in April 2006, aligning with the CENELEC HD 308 S2 standard. Any installation work carried out after 31 March 2006 must use the new harmonised colours, or must be clearly labelled and documented if mixed-colour older wiring exists in the same building. The core identification colours are:
| Conductor | Harmonised Colour (post-2006) | Old UK Colour (pre-2006) |
|---|---|---|
| Line (L1 / live) | Brown | Red |
| Neutral | Blue | Black |
| Earth / CPC | Green and Yellow | Green (or bare) |
| Three-phase L2 | Black | Yellow |
| Three-phase L3 | Grey | Blue |
| Switch wire (SW) | Brown, Black, or Grey | Red |
Where twin-and-earth flat cable is used, the plain grey or white inner core is used as the switch wire and must be sleeved or taped at each end with the appropriate identification colour. Failure to do so is a common fault noted on Electrical Installation Condition Reports (EICRs) in properties with mixed-era wiring.
When and How to Use Electrical Identification Tape
Switch Wire Marking
In a standard two-way lighting circuit using modern 6242Y flat twin-and-earth cable, the grey or white inner core carries the switched live. At every accessory termination — at the switch, at the light fitting, and at any junction box — this core must be sleeved or wrapped with brown tape to indicate it is a line conductor when the circuit is energised. This is a mandatory requirement under BS 7671 Regulation 514.3.1.
In older installations using pre-2006 colour codes, the switch wire was red and this practice was already established. In new work and alterations, brown tape is required.
Three-Phase and Multicore Circuit Marking
In three-phase distribution circuits, a black three-core SWA cable carrying L1 (brown), L2 (black), and L3 (grey) can appear visually confusing at terminations. Phase tapes in the correct harmonised colours — brown, black, and grey — must be applied at each cable end to confirm conductor identity. This is especially important in multicore flexible cables where core colours may differ from fixed wiring standards.
Earth Continuity Conductors
Any bare earth conductor, including the bare CPC (Circuit Protective Conductor) in flat twin-and-earth cable and SWA armoured cables, must be sleeved with green and yellow sleeving at every point where it terminates or is accessible. PVC green and yellow tape can be used where sleeving is impractical, for example where the conductor has already been terminated and sleeving cannot be threaded over it. This is required by BS 7671 Regulation 514.4.2.
Neutral Identification
In multicore cables where core identification is unclear — such as old black single-core singles used as neutrals, or flexible cord with non-standard colours — blue tape must be applied to identify the neutral conductor at each termination point. This is common in older commercial refurbishment work where legacy wiring must be partially retained and documented.
Product Cards
APM Electricals stocks PVC insulation tape in the full BS 7671 harmonised colour range. Each roll is 19mm wide and 33 metres long, meeting the standard width for conductor identification in domestic and commercial electrical installations. All tapes are UL and CE rated.
Choosing the Right Tape for Your Application
PVC Insulation Tape vs Heat-Shrink Sleeving
PVC tape is suitable for conductor identification at terminations and is the most practical option on site. However, for permanent protection of a splice or joint — particularly in a junction box where the tape may be disturbed during maintenance — heat-shrink tubing provides a more secure, weatherproof seal. For outdoor and damp locations rated at IP54 or higher, self-amalgamating tape gives a watertight bond that PVC tape cannot achieve.
For most domestic electrical work, PVC insulation tape in the relevant identification colour is the correct tool for switch wire marking and earth sleeving identification. It is fast to apply, reusable in the sense that it can be unwound for inspection, and available at very low cost per roll.
Tape Width and Thickness
Standard 19mm × 33m tape is the most widely stocked size and is appropriate for cables up to 10mm² conductor cross-section. For larger conductors in sub-main tails or distribution boards, 25mm tape gives better coverage and adhesion. Tape thickness (typically 0.13–0.15mm for standard grades) affects temperature resistance: standard PVC tape is rated to 70°C, which is suitable for thermoplastic (PVC) insulated cables but not for XLPE (cross-linked polyethylene) cables rated above 90°C.
Old Colour Codes and Mixed Wiring Installations
When extending or altering an installation that still has pre-2006 red/black/green wiring, a Regulation 514.14.1 notice must be fixed at the consumer unit to warn that two different wiring colour systems are present. Tape must be applied to new conductors in the new harmonised colours — not the old colours. Applying red tape to new switch wires in an attempt to match existing wiring would create a non-compliant installation and could confuse future maintenance electricians.
A common situation is a house extension where the existing downstairs circuit uses old red-and-black radial wiring but the new rooms are wired in brown-and-blue 6242Y flat cable. Both systems require correct conductor identification at every accessible point, and the advisory notice at the consumer unit is mandatory.
Storage and Site Use
PVC insulation tape should be stored at room temperature. Cold tape (below 5°C) loses adhesion and will peel back from the conductor shortly after application — this is particularly relevant on winter building sites. Warm the roll in a jacket pocket before use if working in unheated properties. Do not stretch the tape when applying it as this reduces the effective insulation thickness; apply with gentle tension, overlapping each wrap by approximately 50%.
On a well-equipped electrical van, a minimum stock of five tape colours is recommended: brown, blue, green/yellow, red, and black. White tape is used for cable labelling and circuit identification at terminal blocks. Grey tape covers three-phase L3 marking in commercial work.
Related Products and Guides
For further reading on conductor identification and BS 7671 compliance, see our guides on WAGO Connectors and Push-Wire Terminals, Light Switches — 1-Way, 2-Way, and Intermediate Wiring, Metal Back Boxes and Dry Lining Boxes, MCBs, RCBOs, and Consumer Units, and Cable Clips and Cable Ties — Fixing Twin-and-Earth and Round Cable.
Leave a comment