Retrofitting LED into an existing refrigeration cabinet should be one of the cheapest, fastest projects a supermarket can run — strip out the old fluorescent, drop in modern LED, immediate energy and visibility improvement. In practice, retrofits fail more often than new builds. Almost always the problem isn't the LED product; it's that someone didn't check the cabinet first.

This is a field guide to what actually goes wrong, drawn from projects we've supported and failures we've been called in to fix. Each section ends with the pre-installation check that would have caught it.

Failure mode 1: Length mismatch forces on-site cutting

The most common installation-day surprise: the supplier ships standard 1200mm bars; the cabinet has 1242mm vertical channels (or 1186mm, or some other non-standard dimension). The installer has two bad choices — leave a visible gap, or cut the bar. Both compromise the project.

Cutting an LED bar voids the IP rating, voids the warranty, and frequently shorts the strip. Leaving a gap looks unfinished and undermines the visual rationale for the upgrade.

Pre-install check

Measure every cabinet — not just one — across the full project. Older fleets have lots that were built in different production runs with different dimensions. Send the measurements with your enquiry; CAPST product lines run in 587 / 900 / 950 / 1202 / 1500 mm (SNK), 600 / 720 / 950 / 1200 / 1350 / 1500 / 1700 mm (SLK), and so on. Custom lengths are available with lead time — confirm at quotation.

Failure mode 2: Wrong CCT for the existing brand standard

Multi-store retailers usually have a brand standard for refrigerated section colour temperature — 4000K is the most common, but some chains specify 3500K or 5000K. Order one shipment with the wrong CCT and an entire store rollout looks visibly different from the existing fleet.

This isn't a small problem. Customer-facing visual consistency across stores is part of the brand standard for almost every modern grocer. A single chiller bay running 5000K next to twenty bays running 4000K reads as broken or under-maintained — even if the products are technically functioning.

Pre-install check: Document the existing CCT before specifying replacement. If the original LED is unmarked, ask the cabinet manufacturer or measure with a colour-temperature meter. CAPST refrigeration LED ships in 3000 / 4000 / 6500 K plus a Fresh-meat specialty colour — pick the match deliberately.

Failure mode 3: Driver under-rated for the connected load

This one we covered in detail in our driver-sizing article, but it bears repeating in the retrofit context. Existing fluorescent ballasts are rarely dimensioned for direct LED replacement. Specifying a 24V DC LED platform means specifying a new driver — and the driver wattage has to clear the connected LED load with at least 10–15% headroom.

Retrofit projects that reuse the original ballast wiring (with a "compatible" bypass arrangement) usually fail in year one. The right answer is a clean break — new 24V DC supply, sized correctly, connected directly to the LED chain.

Failure mode 4: IP rating wrong for the cabinet environment

A surprising number of retrofits specify IP20 ambient-shelving LED into refrigerated multi-deck cabinets. The bars work for a few months; condensation gradually penetrates the unsealed connectors; flicker starts; full failure follows.

The fix isn't expensive — IP65 is the standard refrigeration grade, and CAPST's SLK and SNK series both meet it — but the original specification has to call for it.

"Specifying IP20 into a refrigerated cabinet is buying a six-month product. IP65 is buying a five-year product. The cost difference is small; the operational difference is enormous."

Pre-install check: Identify the cabinet type before sourcing. If it's anything other than dry ambient shelving, default to IP65. See our IP rating guide for the full decision tree.

Failure mode 5: Mounting incompatibility with existing brackets

Older fluorescent fixtures use a specific bracket geometry — usually clip-fit or screw-mount on a particular axis. Modern LED bars use magnet brackets, screw clips with a different pitch, or both. Drop a new product into an old cabinet and the brackets don't line up.

Three options when this happens, in order of preference:

  • Specify an LED bar whose mount matches the existing bracket. CAPST SNK (magnet bracket — white or black finish) suits most metal-frame cabinets without modification.
  • Replace the bracket alongside the LED bar. Adds parts cost but ensures correct fit.
  • Drill new mount points. Last-resort and visible — a sign the project should have been planned differently.

The pre-installation checklist in full

Before placing the first order on a refrigeration LED retrofit, work through every item below. Two hours spent here saves a day per failed cabinet later.

  • Measure cabinet dimensions across the full project — not just one sample.
  • Document existing CCT, CRI, and IP rating; specify replacements to match or improve deliberately.
  • Confirm the new LED bar's wattage range and chain connection rules; size drivers with 10–15% headroom.
  • Identify mounting bracket geometry; pick a bar whose factory bracket matches, or budget for replacement brackets.
  • Confirm operating-temperature window (refrigeration LED: typically −20 °C to +25 °C; high-grade SRL/SPU: −30 °C to +35 °C).
  • Confirm UL listing if the project has North-American or multi-region compliance requirements (SNK and SPU both UL Listed).
  • Plan installation in a single overnight session per aisle — staggered installs across multiple nights cause inconsistency in cabinet-to-cabinet appearance.

If you're scoping a retrofit project right now and want a second pair of eyes on the specification before ordering, share your measurements and current cabinet make/model with us. We've seen most of the field failure modes already and the early questions usually surface the right answer faster than the post-install fix.