Mine Site Lighting: Why Do My LED Fittings Keep Failing?

When mine site lighting fails every two to three years, the costs go well beyond the fitting. A commodity light fitting with that failure rate doesn't just cost more over its life. It costs more in the things mine sites can least afford maintenance hours, access equipment and unplanned work in operating areas.

Voltage transients and sustained high ambient temperature are two of the four most common reasons LED fittings fail early on Australian mine sites. In this blog we will cover what each one does to an industrial LED light fitting and what to look for when specifying LED lighting for mine sites.

The purchase price of an industrial light fitting is the smallest number in the equation. The costs that matter come with a failure: the elevated work platform, the electrician's time, the isolation and access window, and the safety exposure of a dark walkway or conveyor gantry while you wait for all three to line up.

On most sites, the labour and access cost of replacing a single failed fitting is higher than the price of the fitting itself, often several times over.

A failed driver on a $150 commodity fitting costs exactly the same to rectify as one on a premium fitting. The difference isn't the cost per event. It's how many events you end up paying for.

Mine site distribution systems are electrically noisy. Switchgear operations, large motor starts and lightning-induced surges all generate transient voltage events far beyond nominal supply.

Transient damage to LED drivers is among the most common causes of early failure on poorly specified fittings. The failure can't be seen until the light goes out, and a commodity datasheet rarely covers it convincingly.

Transients are a driver design problem. They have to be solved at the design stage, not retrofitted.

•        Surge immunity documented to IEC 61000-4-5, not just a "surge protected" claim

•        Common mode immunity of 4kV or better. This is the figure relevant to switchgear and lightning-induced events.

•        A wide input voltage range with real headroom above and below your site's nominal supply. A fitting running near its rated limit has nothing in reserve when a transient hits.

Raytec's WARRIOR range of heavy industrial LED luminaires build electronic protection into every driver. It is tested to IEC 61000-4-5 at 2kV differential mode and 4kV common mode, with input voltage ranges typically from 110 to 254V AC/DC, depending on the variant.

Heat is the primary enemy of LED lighting. High ambients such as tropical summers, radiant heat from plant and enclosed structures raise LED junction temperatures. Junction temperature governs both lumen depreciation and the likelihood of outright failure.

A fitting rated in a 25°C lab behaves very differently above a conveyor in February.

This failure mode is quiet. Fittings dim gradually for years, and it goes unnoticed until a lux audit or an incident investigation. A fitting that has quietly lost 30% of its output is still "working", right up until light levels at the working plane fail an audit.

LED luminaires are more resilient to temperature extremes than fluorescent, but only when they're engineered for it. Raytec's comparison of WARRIOR Linear against traditional fluorescent fittings shows LED output holding effectively constant from -30°C to +60°C, while fluorescent output collapses at both extremes.

•        Purpose-built LED housings. Some fittings are LEDs retrofitted into housings designed for fluorescent or HID technology, a practice that compromises thermal performance and reliability. A purpose-built housing should be engineered around its LEDs, with the body of the fitting acting as a heatsink that draws heat away from the light engines and driver electronics.

•        Current derating. Rather than driving a few LEDs hard at maximum current, the fitting uses more LEDs driven at carefully controlled levels. This directly reduces each LED's junction temperature, which is the primary factor in lumen depreciation and failure.

•        A published L70B10 lifetime figure and the test basis behind it, not just "long life"

•        A purpose-built LED housing that works as a heatsink

•        Evidence of current derating, and rated performance at the ambient temperatures your site actually reaches

Raytec's WARRIOR range uses a marine-grade aluminium body as an integral heatsink and targets a minimum L70B10 lifetime of more than 100,000 hours.

The other two common failure modes in mining LED lighting are dust, water and seal degradation, and lens contamination from iron ore dust. Our free guide covers the design decisions that help a fitting survive each one.

Across all four, the approach is the same: specify on how a product performs in your application, not on what a catalogue says. That's what we mean by application certainty.

The guide works through all four failure modes and what to look for in a specification for each one. It also includes a total cost of ownership comparison and a consolidated specification checklist, so the same standard can be applied to any product from any supplier.

Pacific Automation can also work through a total cost of ownership comparison with your own site figures as part of a lighting assessment. Contact us on 1300 881 876 or sales@pacificautomation.com.au to speak with a team member today.