Commercial premises lighting serves a dual purpose: it must meet the functional requirements of the workspace while contributing to the aesthetic standard expected in a professional environment. When fittings fail, age, or no longer meet the tenant’s needs, replacement must be carried out in compliance with BS 7671 (the IET Wiring Regulations, 18th Edition) and, where bathroom zones are involved, the specific requirements of Building Regulations Approved Document P.
In this case, the tenant at 85 Great Portland Street was supplying all light fittings directly, a common arrangement in commercial tenancies where the occupier has specific design preferences. The electrical contractor’s role was to ensure that each fitting was installed safely, that new circuits were routed correctly, and that all work met the standards required for certification. The addition of a new bathroom mirror accent light introduced particular complexity: the work required running a new cable supply, installing surface-mounted mini trunking for cable management, and upgrading the existing single pull cord switch to a 2-gang switch capable of controlling two independent lighting circuits.
The Electricity at Work Regulations 1989 require that all electrical systems be constructed, maintained, and used so as to prevent danger. Regulation 4(2) places an ongoing duty to maintain systems in a safe condition, and any new installation or modification must meet that standard from day one.
The Programme of Works
The lighting programme comprised four distinct items, each with its own technical considerations:
Item 1 — Living Room Ceiling Light: Like-for-like replacement of the existing ceiling fitting. While straightforward in principle, even direct replacements require verification of the existing circuit condition, correct termination at the ceiling rose or junction point, and confirmation that the new fitting is compatible with the circuit rating.
Item 2 — Kitchen Ceiling Light: Like-for-like replacement following the same methodology. Kitchen environments may involve proximity to heat sources and moisture, requiring confirmation that fittings carry appropriate IP ratings where applicable.
Item 3 — Bathroom Ceiling Light: Like-for-like replacement within a bathroom zone. BS 7671 defines specific zones (0, 1, and 2) within bathroom spaces, each carrying minimum IP rating requirements for installed equipment. A ceiling-mounted fitting must meet at least IPX4 in Zone 1 (the area directly above a bath or shower) and IPX4 in Zone 2 (extending 0.6m beyond Zone 1).
Item 4 — Bathroom Mirror Accent Light with Switching Upgrade: This item represented the most technically demanding element of the programme. The works required running a new cable supply from the existing lighting circuit to the mirror location, installing all cabling in surface-mounted mini trunking for a neat and compliant finish, installing the accent light with appropriate fixings and connections, removing the existing pull cord switch, and installing a new 2-gang switch to provide independent control of both the ceiling light and the new mirror light.
Initial Site Assessment
Our NICEIC-qualified electrician attended the premises as the first job of the day, allowing an uninterrupted start to what was anticipated to be a multi-hour programme. The initial assessment confirmed the scope of works and identified the cable routing for Item 4. In commercial and residential first-floor premises, cable routing decisions must balance aesthetics (the tenant’s preference for minimal visual impact) against practical constraints (existing cable runs, structural elements, and zone compliance in wet areas).
The decision to use surface-mounted mini trunking for the new bathroom supply was a considered one. While concealed wiring is generally preferred for aesthetic reasons, surface-mounted trunking in a bathroom environment offers several advantages: it avoids the need to chase solid walls or cut into plasterboard (both of which create dust and debris in an occupied space), it allows future inspection and modification without destructive access, and it provides a clear, identifiable cable route that satisfies the requirements of BS 7671 for accessibility of wiring systems.
Electrical Work in Bathroom Zones
Bathroom electrical work carries specific regulatory requirements that go beyond standard lighting installations. BS 7671, Section 701, sets out the special requirements for installations in locations containing a bath or shower. These include restrictions on the types of equipment permitted in each zone, minimum IP ratings for installed fittings, requirements for supplementary bonding (unless the installation meets the conditions for exemption under Regulation 701.415.2), and the requirement that circuits supplying bathroom equipment be protected by a 30mA RCD.
Building Regulations Approved Document P classifies certain bathroom electrical work as notifiable, meaning it must either be carried out by a registered competent person (such as an NICEIC-registered contractor) or be notified to Building Control. The installation of a new circuit in a bathroom — which the mirror accent light effectively required — falls within this scope.
The Switching Upgrade
Replacing a pull cord switch with a 2-gang wall-mounted switch in a bathroom requires careful attention to switch location. BS 7671 prohibits standard switches within Zones 0, 1, and 2 of a bathroom. Pull cord switches have historically been used because the operating mechanism is isolated from the switching contacts. A wall-mounted switch must be positioned outside the defined zones, typically adjacent to the bathroom door. The 2-gang configuration allows independent control of both the ceiling light (Circuit 1) and the mirror accent light (Circuit 2), providing the tenant with the operational flexibility they required.
Common Reasons for Commercial Lighting Upgrades
Understanding why lighting installations require attention helps facilities managers and commercial tenants plan proactive maintenance. The table below outlines the most common drivers for lighting upgrades in commercial premises.
| Driver | Cause | Indicators |
|---|---|---|
| End of Life | Ballasts, drivers, or lamp holders degrade over time | Flickering, delayed start, intermittent failure |
| Aesthetic Refresh | Tenant fitout, change of use, or modernisation | Outdated fittings, poor colour rendering |
| Energy Efficiency | Older fittings consume disproportionate energy | High electricity costs, non-LED technology |
| Compliance Gap | Installation predates current wiring regulations | Missing RCD protection, incorrect zone ratings |
| Functional Change | New use requires different lighting levels or locations | Inadequate lux levels, dark spots, new task areas |
In this case, the primary driver was tenant requirement — the occupier needed fittings that matched their design intent and provided appropriate lighting for each room’s function.
