1. Why coastal corrosion is a system problem

LIKELIGHT publishes outdoor aluminum-alloy wall-washer families [S4]. Aluminum is useful for thermal and structural reasons, but the installed assembly may also include stainless fasteners, plated washers, copper conductors, connector alloys and steel supportwork. NASA explains that galvanic corrosion occurs when dissimilar metals contact in the presence of an electrolyte and conductive path [S2]. Salt deposits attract moisture and keep the interface conductive for longer periods.

2. The four-condition failure model

3. Why a small coating defect can become the focus

At a damaged coating edge, a small exposed active-metal area may be coupled to a much larger cathodic fastener/fixture area. That area relationship can concentrate attack at the defect. A useful screening calculation is:

Illustrative assumption: 100 fastener/washer interfaces expose 300mm² of more noble metal each (30,000mm² total), while coating damage exposes only 10mm² of aluminum at each hole (1,000mm² total). The screening ratio is 30:1. This is not a corrosion-rate calculation; it identifies why small coating holidays around many holes deserve inspection.

4. Connector corrosion is not only an IP issue

An enclosure can resist bulk water yet still suffer contact degradation if salt reaches a pin interface through incomplete mating, damaged seals, capillary cable paths or repeated service opening. Freeze connector manufacturer/model, plating, current, pinout, mating torque/latch, unused-port cap, cable jacket compatibility and replacement process. “Waterproof connector” without these details is not a released specification.

5. Salt-mist testing: what it can support

IEC 60068-2-11 describes a salt-mist method for assessing comparative corrosion resistance and coating uniformity, especially discontinuities such as pores [S1]. It does not provide a universal equation that converts hours in a chamber into years on a specific coast. Outdoor service varies with salt deposition, wet/dry cycles, UV, temperature, wind, washing, orientation, pollutants and maintenance.

6. Product reference and missing decisions

LIKELIGHT L-W-10036-DMX is published as a 36W, DC24V, RGB, DMX512 wall-washer reference [S5]. For a coastal release, still confirm:

• Housing alloy and surface-treatment process.
• Bracket and fastener grades, washers and isolation pieces.
• Connector shell/contact materials and unused-port caps.
• Coating thickness/edge treatment and repair method after field drilling.
• Salt-mist test method, duration, sample state and pass/fail criteria.
• Drainage, orientation, access and cleaning interval.

All six remain 待确认 unless the approved specification/report is supplied.

7. Worked 100-fixture audit

Illustrative project: 100 wall washers on an oceanfront facade. Create one line per fixture with housing, bracket, fastener, substrate, connector, cable exit and drainage fields. Sample every material combination—not just one fixture appearance.

1. Mark every dissimilar-metal interface on the drawing.
2. Identify where coatings are penetrated during installation.
3. Check whether water can pond behind brackets or connector backshells.
4. Separate protective isolation from required electrical bonding/earthing; resolve conflicts with the project engineer.
5. Define factory test samples that include actual bracket, fastener and connector.
6. Define baseline photos and acceptable cosmetic/functional change.
7. Schedule inspection after commissioning and the first severe coastal season; exact interval is project-specific.

NASA's bonding guide similarly calls for material/finish selection, drainage, sealants and documented maintenance when corrosion and bonding requirements interact [S3].

8. When not to approve the system

• The quote says “stainless screws” but gives no grade or mating-metal review.
• Salt-spray hours are stated without method, sample configuration and acceptance criteria.
• Field-drilled coating damage has no repair process.
• Connector caps, spare connectors and replacement mating instructions are missing.
• Brackets trap water or cannot be inspected.
• Electrical isolation and protective bonding requirements conflict but remain unresolved.

9. Evidence ledger

10. FAQ

Is stainless steel always safe with aluminum?

No. Compatibility depends on exact alloys, finishes, geometry, electrolyte exposure and isolation; obtain a materials review.

Does IP67 prove salt-corrosion resistance?

No. Ingress protection and corrosion resistance are different evidence categories.

Can salt-mist hours predict service life?

Not through a universal conversion. Use them for controlled comparison with defined criteria [S1].

Should all dissimilar metals be electrically isolated?

Not blindly. Isolation can conflict with bonding/earthing; the electrical and corrosion design must be resolved together [S3].

What should be photographed?

Coating edges, fasteners, bracket drainage, connector pins/seals, unused caps and representative pre-installation baselines.

Who authored this guide?

Author: LikeLight Tom, Operations. Technical reviewer: 待确认.