FAQ: lighting logic

Phil Brown, Product & Marketing Director at NVC Lighting, provides some practical insights for professional electricians.

Q1. What is CRI and why is it an important consideration when choosing commercial lighting?
CRI, or Colour Rendering Index, is a measure of how accurately a light source reveals colours compared to natural light, rated from 0 to 100. In retail, hospitality and office spaces, a CRI of 80+ is acceptable, but for applications like healthcare, art galleries or design studios, a CRI of 90+ is essential to avoid colour distortion.

Electricians should check CRI ratings during installation, especially when retrofitting existing buildings.

Q2. What does UGR<19 mean and when should it be considered?
UGR (Unified Glare Rating) measures the amount of discomfort glare produced by luminaires within a space. A rating of UGR<19 is recommended for environments where visual tasks are performed for extended periods – such as offices, classrooms and meeting rooms – where task lighting is critical.

Electricians should ensure that specified fittings meet this threshold to comply with lighting design standards and to help reduce eye strain and visual discomfort for occupants.

Q3. How critical is proper lighting control in commercial installations? 
Smart lighting controls – such as occupancy sensors, daylight harvesting and programmable dimming – can dramatically enhance energy efficiency and user comfort in commercial spaces.

It’s essential that electricians coordinate closely with lighting designers and controls engineers to ensure wiring layouts and control zones are planned accordingly. Importantly, the use of absence/presence detectors and automatic lighting controls is now actively encouraged under the 2022 edition of Part L of the Building Regulations, reinforcing the move towards more intelligent, energy-conscious installations.

Q4. What should electricians know about emergency lighting integration?
Electricians need to ensure correct circuit separation, battery backup verification, and proper signage illumination, particularly in escape routes and high-occupancy areas.

Emergency lighting isn’t just a box to tick, it is a safety critical system, and it must comply with codes of practice like BS 5266 in the UK.

Q5. How does IP rating affect light fixture selection in commercial environments?
IP (Ingress Protection) ratings define a fixture’s resistance to dust and moisture. In commercial kitchens, washrooms or industrial zones, higher IP ratings (like IP65) are required. Misjudging IP requirements can lead to premature failure or even legal non-compliance.

Q6. Are there mounting considerations electricians should be aware of?
Absolutely. Recessed vs. surface-mounted, suspension kits and modular grid ceilings all influence installation complexity. Electricians should review ceiling types, fixture weight and support systems to ensure safe and secure fitting, especially in seismic or high-traffic environments.

Q7. Is there a standard approach for DALI or 1-10V dimming systems?
These systems require specific wiring protocols. DALI (Digital Addressable Lighting Interface) uses a bus system and allows individual addressability, while 1-10V is analog and simpler. Electricians must ensure compatibility with luminaires and controllers and avoid mixing systems without appropriate interfaces.

Q8. What is the role of lighting layout plans for electricians?
A good lighting layout plan includes luminaire types, circuits, switching, emergency points and control zones. Electricians should verify these plans onsite, flag inconsistencies, and ensure that cable runs and load calculations align with the design for safety and performance.

nvcuk.com

This article appeared in Electrotechnical News July/August 2025 edition – read it here