Two street lights on a catalogue page can look identical. In the hand, they are not. Housing material and construction decide how heat leaves the LED board, how a gasket compresses and how the fixture ages outdoors.

The Thermal Path

An LED converts a share of its power into heat, and that heat must travel somewhere. In a die-cast aluminium housing, the board mounts directly to a machined surface with a short, wide path to the fins. In a folded sheet-metal body, the board often sits on a separate carrier, adding an interface that traps heat.

The result is a higher junction temperature in the sheet-metal design, which accelerates lumen depreciation and shortens driver life. It is invisible on a datasheet and obvious in year three.

Sealing Is a Machining Problem

A gasket only seals if it is compressed evenly. A machined groove gives a consistent depth around the perimeter; a folded seam does not. That is why water often enters at a corner rather than along a straight edge. Separate seals per compartment make the design more forgiving, because one weak joint does not flood the electronics.

What Buyers Can Check by Hand

1. Run a finger along the gasket groove. Is it continuous and uniform?
2. Look at the back of the housing. Are the fins thick enough to spread heat, or decorative ridges?
3. Check the cable entry. A threaded gland with strain relief is a different class from an open grommet.
4. Inspect coating at edges and inside corners, where corrosion starts.
5. Ask whether the board is mounted to the housing or to a plastic carrier.

Why It Matters in Hot and Coastal Markets

Heat and salt are a harsh combination. A housing that runs hotter ages its electronics faster, and a coating that fails at an edge lets chloride reach the aluminium. The failure often appears as a driver fault, months after the real cause.

“You cannot see a heat sink in a photo. You can feel it in your hand." — Factory engineer

The Practical Rule

If two fixtures have the same wattage and one is noticeably lighter, ask where the heat goes. The answer usually explains the price difference better than any brochure.