Industrial Lighting White Paper

Industrial Lighting White Paper

Scene-by-scene selection, protection ratings and the economics of a retrofit

Queendom Lighting Solutions Group · Industrial Application Engineering

Industrial lighting is not domestic lighting made larger. A factory floor, a cold store and a chemical plant present three different failure modes, three different compliance regimes and three different maintenance economics. A luminaire that survives one of them is not evidence that it survives the others. This paper sets out the four industrial scenes Queendom builds for, the protection ratings each one actually requires, and the calculation a buyer should run before accepting a payback claim.

The numbers below are typical values for the luminaires named. They are stated with the conditions under which they hold, because a luminous efficacy quoted without an ambient temperature and a driver configuration is not a specification.

1. The four industrial scenes and what breaks in each

Most specifying errors come from treating “industrial” as one environment. Segment the project first; the luminaire choice follows almost automatically.

The last column is the floor, not the target. A cold store rated IP65 but not rated for −40 °C starting will fail at the driver, not at the seal, and the failure will look like a power problem rather than a specification problem.

2. Optical performance: luminous efficacy is the least interesting number

Luminous efficacy (lm/W) is the number printed largest on the box and the one that says least about the installation. Two luminaires at 160 lm/W can deliver markedly different maintained illuminance because they differ in optical distribution, in thermal derating and in the maintenance factor they assume.

The maintenance factor deserves its own sentence. It is an assumption about dirt, lamp depreciation and cleaning interval — it is not a property of the LED. Substituting the factory figure for the figure appropriate to a foundry is how a project passes at design review and fails at commissioning.

3. Electrical performance and the driver

Industrial sites are electrically hostile in a way domestic installations are not: contactor switching, welders and large inductive loads all inject transients. A driver without surge protection will be replaced long before its electrolytics wear out, and the replacement will be attributed to the LED rather than to the installation.

4. Reliability figures and how to read them

A 50,000-hour L70 figure and a 5-year warranty are not contradictory; they answer different questions. The first describes a population of luminaires under a stated ambient, the second describes what the supplier has agreed to do when one of them fails. Buyers who read the first as the second are the buyers who are disappointed.

5. Energy economics: the calculation, not the claim

5.1 Legacy comparison

5.2 Worked example — warehouse, 12,000 m², 9 m mounting height

A distribution centre replaces 320 high-pressure sodium luminaires (400 W system) with LED high bays at 150 W system. Operating hours are 4,400 h per year; electricity is ¥0.85 /kWh.

The maintenance line is the one most often omitted and, in a high-bay installation, frequently exceeds the energy line once access equipment is costed. Any payback model that counts only kWh understates the case for the retrofit.

6. Protection ratings: what the codes actually require

Explosive-atmosphere rating is not a property that can be added by choice of diffuser. Ex d enclosures are a construction type with a defined flame path, and a luminaire either is one or is not. It cannot be approximated, and installing a non-rated luminaire in a zoned area is a compliance failure that no photometric performance can offset.

7. Control strategy: dimming is not the same as saving

DALI-2 and 0–10 V are transport protocols, not strategies. The saving comes from the control logic layered on top of them, and that logic has to be matched to the occupancy pattern of the specific building rather than applied as a template.

• Occupancy sensing pays where aisles are empty for long, predictable intervals — racking areas qualify, a continuous production line does not.
• Daylight harvesting pays where there is a genuine daylight aperture and a control zone small enough to dim without objection — skylit warehouses qualify, windowless cold stores do not.
• Constant lumen output pays where the maintenance factor is high and access is expensive, because it trades a small standing energy cost for a large access saving.
• Scheduling and metering rarely saves energy on its own, but it is what turns a savings claim into a measurement.

8. Common mistakes in industrial specifications

• Specifying by luminous efficacy alone, with no optical distribution stated.
• Taking the factory maintenance factor (typically 0.8) for a dirty process environment (0.6 or lower).
• Assuming a driver rated for the supply voltage is rated for the site transients. It is not.
• Reading L70 life as a warranty period. It is a population statistic.
• Applying a cold-store luminaire that meets IP65 but has no sub-zero start rating for the driver.
• Approximating explosive-atmosphere protection with a sealed, well-built luminaire. This is a compliance failure, not a performance compromise.
• Costing the retrofit on energy alone and omitting the avoidance of one relamp cycle per luminaire.

9. Specification checklist

A quotation request that carries all eight lines below can be answered exactly. One that omits several will come back as a range, and a range is what ends up in the tender.

• Scene classification, and the dominant stress that follows from it.
• Required maintained illuminance (lux) and the maintenance factor to be assumed.
• Mounting height and the spacing-to-height ratio the optics must achieve.
• Ambient temperature range, including the minimum starting temperature.
• IP and IK ratings, plus any corrosion category or hazardous-area zone.
• Dimming protocol and the control strategy it is serving.
• Annual operating hours and the electricity tariff used for the payback model.
• Whether access equipment is required for replacement, and its cost.

10. Conclusion

Industrial lighting decisions are made correctly when the scene is named first and the luminaire is chosen second. Efficacy is a useful filter and a poor specification; protection ratings, ambient range and the maintenance factor assumption do more to determine whether the installation performs in year five than any figure printed on the front of a catalogue. A retrofit that omits the access and maintenance saving from its own business case is usually understating itself, and one that omits the maintenance factor from its photometric model is usually overstating itself.

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Queendom · figures in this paper are typical values for the series named and are subject to the measurement conditions stated. Product commitments are made on the datasheet and in the contract, not here.