Why Some Enclosures Crack Outside?

The weather is working against it — all day, every day

A distribution board installed outside is put through rough conditions. And it's rarely one single factor that kills it — it's the combination.

1. UV light breaks the material down over time. Sunlight is the biggest culprit. The UV radiation in sunlight attacks the polymer chains in the plastic, causing photo-oxidation. The result is a surface that gradually becomes chalky, brittle, and weak. A board that's been exposed to years of direct sun can start to crack even with very little stress because the plastic itself has lost its toughness. Aside from losing its integrity, plastic turns yellow and ugly- looking. UV stabilizers inside the material slow this down, but the wrong material, or one without enough stabilizing, will age fast.

2. Temperature swings cause fatigue. Outdoor boards heat up and cool down constantly. That cycle makes the plastic expand and contract, and every expansion is a small mechanical strain. Over thousands of cycles, the material fatigues, and cracks appear — most often at the points where the board is under the most stress: the corners, the mounting holes, and the areas around screw fixings. This is thermal cycling, and it's one of the most underrated causes you'll see in the field.

3. Moisture does more damage than you'd think. Rain, condensation, and high humidity all work into the plastic. Water can be absorbed into the material, causing swelling, and in cold climates, that trapped water freezes and expands — this is how you get frost cracking. The seals and gland entries are the weak spots here; if water gets in and can't get out, it'll find a way to attack from the inside too.

4. Chemicals and pollution eat away at it. If the board sits near the sea, the salt in the air attacks the plastic. Near industrial sites, chemical fumes do the same. It's not always visible right away, but this kind of exposure accelerates aging dramatically.

Material choice is the difference between a board that lasts and one that doesn't

Here's the thing that often gets overlooked: not all plastics are meant to live outdoors. A standard indoor-grade ABS or PVC board might be perfectly fine in a plant room, but put it in direct sun and it'll degrade much faster than a properly UV-stabilized outdoor formulation. When you're choosing a board for outside, you need to be thinking about:

• UV-stabilized materials — designed specifically to resist photo-oxidation. This is preventing plastic turn yellow and decomposing.
• Impact modifiers — so the plastic stays tough instead of turning brittle as it ages.
• A formulation that can handle thermal cycling — one that is meant to handle rough conditions and stay strong, like ASA.

It's tempting to go for the cheaper board, especially when the difference isn't obvious on the spec sheet. But usually cheap option is what cost the most- it's goes down fast, and now you don't need just a replacement board. You need an installer to get the old one down, install a new one- and not for free.

Installation matters more than most people think

Environment and material are the big ones, but the way the board is fitted in the first place plays a real part too.

• Over-tightened screws put concentrated stress on the plastic and create a starting point for cracks.
• Mounting to an uneven or warped surface twists the board and leaves it under constant tension.
• A board that's too small for the job gets packed tight, forcing the wires and creates internal pressure.
• No provision for expansion in areas of high heat means the board has nowhere to move when it heats up.

Everything stated above plus the stress of weathering, is what makes the difference between a small hairline crack and a board that's failed completely.

The honest takeaway

If your distribution boards keep cracking outdoors, you're usually dealing with a mix of three things: the material isn't properly rated for UV and weather, the board is handling thermal cycling it wasn't designed for, or the installation is putting stress on the plastic. Fix any one of those and you'll get further; fix all three and the problem disappears.

The best boards for outdoor use are built from day one to handle sunlight, heat, moisture, and temperature change — and are installed with the care they deserve. When in doubt, pick a board that's genuinely rated for outdoor service, and check it's going onto a flat, solid surface with evenly tightened fixings.

Our D Series distribution boards are engineered from ASA — a material that handles outdoor conditions the way your board should. It's built to shrug off UV radiation and weathering, stay tough through temperature swings, and resist moisture and impact.

The D series keeps its strength, its color, and its integrity — year after year, in the harshest conditions.

Our products are delivered with installation accessories and detailed assembly instructions- so you can follow up every step carefully without fear of damaging the box.