Short answer: a small sealed diecast aluminum box protects a 5-10 W gateway stack from dust and rain, and it cooks the build on a hot wall. A 7 x 5 x 3 in [180 x 130 x 75 mm] diecast case sheds about 3 W at the 12 K rise a hot site allows. A sunlit grey wall runs roughly 8 K above air temperature. Size the wall instead: 0.18 m² [279 in²] of stainless surface carries that load at 50 C ambient in sun. That area is a 16 x 12 x 8 in [406 x 305 x 203 mm] wall-mount enclosure, manufacturer-rated NEMA 4X-type / IP66, not UL listed. Keep 0.4-0.6 in [10-15 mm] of air around stacked boards and feed the build through IP66 glands. The worked example uses an 8 W example load; meter your own build and swap it in before ordering.
How much heat does a gateway board set really make?
Count essentially the whole DC draw as heat. A single-board computer pulls about 5 W under load, and a radio concentrator board adds about 3 W. That puts roughly 8 W into a sealed box, because well under 1 W leaves as radio signal.
Meter the finished build instead of trusting a datasheet. A USB power meter or the PoE switch port readout gives watts with the radio transmitting. That is the number the wall math needs. Idle builds sit near 2-3 W, and a cellular modem can double the load. Size the wall for the metered draw plus 25%, so that stack gets a wall sized for 10 W.
Which boards you run changes the watts, not the method. The radio choice and antenna placement are their own question, covered in putting an indoor LoRaWAN gateway in an outdoor enclosure. For a lighter build, will a low power board overheat in a sealed outdoor enclosure shows where the passive margin comes from.
How hot is too hot inside a sealed box?
Set the inside-air limit at 70 C. That is the top of the 0-70 C commercial range most boards and their electrolytic capacitors are rated for. At a 50 C site ambient it allows a 20 K rise, and a sunlit wall cuts that to about 12 K.
Design to that number and the build runs at full clock speed for its whole life. Let the box run past it and the electrolytic caps in the power section age roughly twice as fast for every extra 10 K. The rise you accept sets the service life. Silicon tolerates higher junction temperatures, but capacitors and radio modules are the parts that call 70 C.
The wall carries the whole load in a sealed box, which is why the options narrow so fast. Removing heat from a small sealed IP66 enclosure compares them for exactly this box class.
What ingress rating does an outdoor electronics box need?
Order a manufacturer-rated NEMA 4X-type / IP66 enclosure and write both marks on the order. The first 6 is dust-tight. The second 6 is a powerful-jet test with a 12.5 mm nozzle at 100 L/min, and NEC 110.28 keeps the IP code and the type rating separate for US installations.
The two marks test different things and never convert into each other. IP66 says nothing about immersion, which starts at IPX7: 1 m for 30 min. Any part fitted later sets the assembly rating, so a drain, a louver or a gland rated below the box drags the whole enclosure down to that part's number. NEMA publishes the type definitions but tests nothing; the rating you rely on is the manufacturer's. Our wall-mount line comes rated NEMA 4X-type / IP66 by the manufacturer, not UL listed. Where a project demands a listing, a UL listed enclosure is one evaluated by UL to UL 50E — put that line on the order explicitly.
The digit-by-digit meanings sit in the IP rating chart, and the outdoor enclosures guide walks the step from environment to rating.
How much wall does that load need at 50 C?
Size the vertical wall from A = Q ÷ (k × ΔT). At a 12 K rise that is 0.12 m² [188 in²] of painted metal for the 8 W example load, or 0.18 m² [279 in²] of bare stainless. The small diecast case, with 0.046 m² of wall, misses both.
Worked example, with the example inputs spelled out: 8 W of heat, 50 C ambient, 58 C effective ambient once sun adds its 8 K, 70 C inside limit, so the rise you design for is ΔT = 12 K. (8 W is 27 BTU/hr, if you think in BTU/hr: 1 W = 3.413 BTU/hr.)
- Painted diecast case, 7 x 5 x 3 in [180 x 130 x 75 mm]: A = 2 × (7 + 5) × 3 = 72 in² [0.046 m²]. Heat out at 12 K: 5.5 W/m²K × 12 K × 0.046 m² = 3.0 W. Rise with the full load inside: 8 ÷ (5.5 × 0.046) = 32 K, so the air reaches about 90 C and the build fails by 20 K.
- Stainless wall-mount box, 16 x 12 x 8 in [406 x 305 x 203 mm]: A = 2 × (16 + 12) × 8 = 448 in² [0.29 m²]. Heat out at 12 K: 3.7 × 12 × 0.29 = 12.9 W. Rise with the same load: 8 ÷ (3.7 × 0.29) = 7.5 K, so the air sits near 65 C. A 10 W stack still holds at 9.3 K, about 67 C.
| Box | Vertical wall | Heat out at 12 K | Inside air at the 8 W load | Verdict |
|---|---|---|---|---|
| 7 x 5 x 3 in painted diecast | 72 in² [0.046 m²] | 3.0 W | 90 C | Fails by 20 K |
| 16 x 12 x 8 in stainless | 448 in² [0.29 m²] | 12.9 W | 65 C | Passes, holds 10 W too |
A drive vendor's sizing note rounds this to 0.125 W/in² [194 W/m²] of vertical steel wall. That shortcut works out to a 35 K rise on painted metal (194 ÷ 5.5 = 35). It is fair at a 30-35 C ambient and about three times too generous at a 50 C site in sun: it credits the diecast case with 9 W (0.125 × 72) against the 3.0 W the 12 K rise allows. Use the ΔT your site actually has.
The conduction path itself is worked through in sealed enclosure conductive cooling through the wall, and the 10-15 W class gets the same treatment in small enclosure heat dissipation for 10 to 15 W.
How much does sun on the wall add?
Full sun adds roughly 8 K to the wall before your electronics feel it. Grey paint absorbs about half of the 1044 W/m² peak solar load, which turns a 50 C day into about 58 C of effective ambient for sizing.
Expect 5-10 K across colours and hours, with 8 K the figure measured on grey paint at the 1044 W/m² standard peak. Lighter finishes absorb less, a shaded face removes the term, and a sheet-metal sun shield removes most of it. How a sun shield cuts solar heat load on an enclosure sizes the shield, and the solar heat load walkthrough carries the irradiance math end to end.
Diecast aluminum or stainless for the wall?
Painted diecast aluminum earns its place only on a small, shaded, salt-free wall. Take 304 or 316L stainless for the washed, coastal or heat-soaked sites. The temperature math above is usually what rules the small aluminum case out first.
The conductivity gap is modest. Paint radiates well, so painted walls carry about 5.5 W/m²K against 3.7 W/m²K for bare stainless. That is why the stainless box above needs a third more area for the same watts. Corrosion decides the rest. Chloride stress-corrosion cracking starts near 60 C [140 F] for 304 and 316L alike, and 304 pits at room temperature under salt deposits sitting in gasket crevices, so coastal and washed-down sites get 316L. The coastal radio enclosure article carries the salt-side checks.
Our catalog is 304 and 316L stainless wall-mount and HMI enclosures, cut and sized to order from 6 x 4 x 4 in up to 60 x 36 x 16 in. The stainless enclosure size finder filters the line by size and grade.
How much clearance do stacked boards need?
Leave 0.4-0.6 in [10-15 mm] of clear air around each stacked board and between the top board and the wall. Then the box's internal air can actually carry the load from the stack to the metal instead of pocketing it between two PCBs.
Stand the stack on standoffs so both faces see air, keep the antenna side facing the free space, and leave about 0.6 in [15 mm] in front of each gland and bulkhead for the connector barrels. A small internal fan helps, though it adds no cooling capacity of its own: it moves heat from the boards to the wall faster. Count its draw, about 1-2 W for a 40 mm brushless fan, into the load. The internal fan walkthrough traces where that heat ends up. Heater sizing guides add an axial fan past about 150 W just to stir cabinet air; in a build of this size a 40 mm fan does the same stirring for a watt or two.
What goes on the order?
Order a 304 stainless wall-mount enclosure 16 x 12 x 8 in [406 x 305 x 203 mm] — 316L within range of salt spray — manufacturer-rated NEMA 4X-type / IP66, with a mounting panel, wall feet and two IP66-rated cable glands.
Every line traces back to a number above, so the quote comes back right the first time:
| Line item | What to order |
|---|---|
| Rating | Manufacturer-rated NEMA 4X-type / IP66 — state both marks, not UL listed |
| Material | 304 stainless inland; 316L within range of salt spray or washdown |
| Outside size | 16 x 12 x 8 in [406 x 305 x 203 mm], sized for an 8-10 W load at a 12 K rise |
| Wall check | 448 in² [0.29 m²] of vertical wall sheds 12.9 W at 12 K; the example load leaves a 7.5 K rise, about 65 C inside |
| Board fit | 0.4-0.6 in [10-15 mm] air gaps around stacked PCBs, standoffs onto the mounting panel |
| Entries | Two IP66-rated glands, feed plus spare, bottom-entry with a drip loop; IP66 antenna bulkhead |
| Options | Your cutouts, hinge side and panel layout, made to your drawing |
| Delivery | Delivered in 10 business days, anywhere in the world; custom work counts from your drawing approval |
Where the next step is choosing between sizes or handing off a custom build, the enclosure selector filters by environment, listing and usable inside dimensions and carries the answers into a quote. Feed it the worst case, the 50 C afternoon with sun on the wall, and let the wall math above set the depth.
Catalog dimensions to compare
Compare these catalog dimensions with your component layout. Open each enclosure for its rating, material and usable space, then check those specifications against your application.
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 16 × 12 × 8 in | 304 stainless | 16 x 12 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 24 × 20 × 8 in | 304 stainless | 24 x 20 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 30 × 24 × 10 in | 304 stainless | 30 x 24 x 10 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 12 × 10 × 6 in | 304 stainless | 12 x 10 x 6 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
Can I drill a vent to cool the box instead?
The vent sets the rating: an assembly with a 6 mm drain or an open plug is only as sealed as that hole, so the NEMA 4X-type / IP66 mark is gone the moment you drill. Keep the wall as the heat path, and treat a filtered fan kit as a different, vented design with its own size math.
How many watts can the small diecast case take in the shade?
About 5 W: a 7 x 5 x 3 in case has 72 in² [0.046 m²] of vertical wall, and at 5.5 W/m²K it sheds 5.1 W at a 20 K rise, reaching 70 C from a 50 C ambient. Treat 3-5 W as the ceiling in shade and about 3 W with the wall in full sun.
Does an outdoor antenna bulkhead ruin the IP66 rating?
Not when it is a proper bulkhead connector: a round hole with the supplied O-ring and lock nut onto a flat pad holds IP66 at the joint. A cable pushed through a plain drilled hole does not, and a drip loop below any entry keeps running water off the gland.
What happens on the -5 C end of the range?
Cold does not cook boards; the day-night cycling moves moisture. Every 10 K of cooling pulls about 3% of the internal air back in through the weakest joint, so a 25 L box swallows roughly 0.8 L of outside air per 10 K drop. A manufacturer-rated IP66 pressure-equalization vent, fitted as its datasheet describes, breaks that cycle without giving up the rating.
Does a heatsink on the processor save the small box?
It helps the chip and not the box: the finned sink only moves heat into the same sealed air, and the wall still sheds the full load, so the small case still climbs about 32 K and lands near 90 C. A sink pays off only when it is bonded through the wall itself, which is a custom thermal design.
Is IP66 enough if the site gets hosed down?
Yes for hose and jet wash: the second digit 6 is proven with a 12.5 mm nozzle at 100 L/min. Hot, high-pressure washdown is digit 9 territory, and the stainless wall-mount line is manufacturer-rated NEMA 4X-type / IP66 rather than IP69, so describe the wash method on the order and match the rating to the hose.
