Short answer: take the bracket down and mount a box, and buy it for the weather the soffit actually stops. A deep, sheltered eave makes the spot a damp location, so a gasketed Type 3R box is the floor. Where wind-driven rain or drifting snow wets the soffit face - most eaves - fit a NEMA 4X / IP66 stainless box and you cover damp, wet and hose-down in one rating. Bring the cable in through a gland in the bottom wall and hang a drip loop beneath it. Our wall-mount boxes are rated NEMA 4X-type / IP66 by the manufacturer; they are not UL listed.
What the eave stops, and what it does not
Falling rain arrives close to vertical and the overhang sheds it cleanly. Rain that comes in with wind strikes at a shallow angle and wets the soffit face directly, and a shallow eave delays it by a second or two. Drifting snow does the same in winter, worst on the side facing the prevailing wind. The spot is still outdoors, just gentler: the NEC defines a damp location as protected from the weather, not saturated with water, yet exposed to moderate moisture, and that reads like a soffit. So you mount a box marked for outdoor damp use; an indoor box carries a dry-location rating and stays inside.
The cable dropping through the soffit is its own water path. Water tracks down the sheath and pools in any opening that grips the cable, which is why the entry belongs in a gland in the bottom wall. The full routine - glands, loops and drains - is in sealing an outdoor junction box.
The rating to mount
NEC 314.15 sets the job in one line: a box in a damp or wet location is placed or equipped so moisture can neither enter it nor collect inside. NEC Table 110.28 then matches enclosure types to location conditions, and NEC 110.28 adds that an IP code on its own does not replace a type rating in a US installation. So the marking you shop for is the type, with the IP code alongside it.
Type 3R, in the NEMA 250 definitions, is built for outdoor use against falling rain, sleet and ice, and it is designed to drain. NEC 314.15 permits drainage openings of 3 mm (1/8 in) to 6 mm (1/4 in) in boxes listed for damp or wet locations. Type 4X keeps the water out with a gasket instead of a drain, adds hose-down jets, and adds corrosion resistance: under the NEMA 250 / UL 50E test it takes another 200 hours of salt spray, judged against a 304 stainless specimen. IP66 pairs with it. The first digit 6 is dust-tight; the second digit 6 means powerful jets, which IEC 60529 tests with a 12.5 mm nozzle at 100 L/min from 2.5 to 3 m for at least 3 min. The type tables behind this are in the NEMA enclosure types guide and the 3R vs Type 4 comparison.
Decide it this way. A deep eave on a wall that breaks the wind - a covered porch with the box 12 in [300 mm] inside the drip line - earns a 3R box. Everywhere else, and anywhere you would rather buy one box for every eave on the job, mount 4X. Then hold the weakest-part rule: the assembly keeps the lowest rating among box, gland and any hole you cut, so a 4X box wants an IP66 gland and no field-drilled openings.
304 or 316L for the soffit box
An inland eave that dries out between rains is easy duty for 304 stainless, and that is the default grade for this job. Chlorides are what move it: 304 can pit at room temperature under a salt deposit sitting in a gasket crevice, and the molybdenum in 316L is what resists that pitting. Buy 316L when sea air reaches the soffit, or when winter road-salt mist drifts up under the eave. Both grades run into chloride stress cracking above about 60 C (140 F), a temperature a floodlight box never sees under a soffit. You can filter the catalog by grade in the stainless size finder.
Heat check: a 15 W camera supply in a 6 x 4 x 4 in box at 35 C
Most camera floodlights keep their power supply in the lamp head, so the box holds splices and adds no heat. Run this check when your install carries the supply in the box instead.
Inputs: the smallest wall-mount body we build, 6 x 4 x 4 in outside, at the bottom of a catalog that runs to 60 x 36 x 16 in; stainless walls at k = 3.7 W/m2K, this site's reference value for stainless; 35 C ambient under a sun-loaded soffit; a 40 C interior limit, the usual figure for electronics unless the datasheet allows more; and a 15 W supply at 88% efficiency, a typical figure for this duty and this example's assumption.
The rule in words: heat leaves through the walls, and the temperature rise equals the heat divided by k times the wall area.
- Wall area: 2 x (0.152 x 0.102 + 0.152 x 0.102 + 0.102 x 0.102) = 0.083 m2
- Heat the box carries at the allowed 5 C rise: 3.7 x 0.083 x 5 = 1.5 W
- Heat the supply makes: 15 x (1 - 0.88) = 1.8 W
- Resulting rise: 1.8 / (3.7 x 0.083) = 1.8 / 0.31 = 5.8 C
- Interior: 35 + 5.8 = 40.8 C
That clears 40 C by the wrong margin. Keep the supply in the lamp head and the box runs at 0 W, or step up a body size: doubling the wall area to 0.17 m2 halves the rise to 1.8 / (3.7 x 0.17) = 2.9 C, putting the interior at 37.9 C. The threshold to carry away: in the smallest body, at 35 C ambient, you have about 1.5 W of heat to spend.
Mounting it without losing the rating
Kill the breaker and confirm the conductors are dead before you open the old splice - one habit, every fixture change. Then fix the box to framing or a sound trim board rather than to the soffit skin alone. Our wall-mount boxes carry feet, and fastening through the feet leaves the sealed body untouched; when a fastener must pass through the wall, seal it the way mounting screws through an outdoor enclosure without leaks shows, because the box then keeps only what that hole allows.
Set the gland in the bottom wall, or in the lowest side wall, and keep entries off the top face - cable glands facing up on an outdoor box is the short version of why. Dress the cable into a loop that hangs 3 in [75 mm] below the gland before it turns up into it, so water running down the sheath drops off in open air. Where the cable drops through the soffit straight behind the box, gland the back wall and run a bead of UV-stable sealant under the flange. Bond the body so the fixture grounds through it; the stainless specifics are in cable gland bonding for stainless junction boxes.
From the box to the floodlight you have two clean paths. Run a short glanded whip out to an arm-mounted lamp, with the entry details from the floodlight camera gland and strain-relief article. Or set the floodlight base over a flush box the way the recessed soffit junction box article describes, with its gasket landing on a flat, uncut surface. Either way, the finished assembly keeps the lowest rating among box, base gasket and gland.
What to put on the order
| You order | Specify | Why |
|---|---|---|
| Body | Wall-mount stainless, hinged gasketed door, removable mounting panel | splice access and a land for grounds |
| Grade | 304 inland; 316L where sea air or road salt reaches the soffit | 304 pits under chloride deposits |
| Size | 6 x 4 x 4 in for splices only; one size up with a supply inside | 1.5 W ceiling at 35 C ambient |
| Rating | NEMA 4X-type / IP66, manufacturer-rated, not UL listed | wind-driven rain, snow, hose-down |
| Entry | One gland hole in the bottom wall, cut to your gland's thread | keeps the assembly at IP66 |
| Cover | Flat gasketed plate where a floodlight base lands over the box | base gasket seals on an uncut face |
You set the size, the grade and every cutout on the drawing, and the box is delivered in 10 business days - counted from your order, or from your approval of the drawing for custom work. If you want the shortlist before you draw it, the enclosure selector narrows the catalog by environment and inside dimensions.
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 |
|---|---|---|---|
| 6 × 6 × 4 in | 304 stainless | 6 x 6 x 4 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 8 × 6 × 4 in | 304 stainless | 8 x 6 x 4 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 10 × 8 × 4 in | 304 stainless | 10 x 8 x 4 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
Is under the eaves a damp or a wet location?
Damp, when the eave genuinely sheds the weather: the NEC's damp definition covers places protected from the weather, not saturated with water, yet exposed to moderate moisture. When wind-driven rain or drifting snow wets the soffit face, treat the spot as wet. A NEMA 4X / IP66 box is rated for both, which is why it is the one-box answer for most eaves.
Can an indoor box go under the eaves because it is covered?
Use a box marked for outdoor damp use instead. An indoor box carries a dry-location rating only, and a covered soffit still sees humidity, wind-blown spray and the water that tracks down the cable sheath. A Type 3R box adds falling rain, sleet and ice; a 4X box adds hose-down jets, tested at 100 L/min from a 12.5 mm nozzle.
Should I drill a drain hole in the box?
Keep a Type 4X box sealed all round; a field-drilled hole brings the assembly down to the drain's level. Drains belong on 3R boxes: NEC 314.15 permits openings of 3 mm (1/8 in) to 6 mm (1/4 in) in boxes listed for damp or wet locations, and a 3R body is built to shed water past them.
Does the floodlight base make the box weatherproof by itself?
Only where its gasket lands on a flat, uncut surface. The assembly keeps the lowest rating among the box, the base gasket and the gland, so a 4X box under a base with a poor gasket is only as good as that gasket. A flush box with a flat gasketed cover plate under the base is the clean arrangement.
How much heat can the smallest box take?
About 1.5 W at 35 C ambient. The 6 x 4 x 4 in stainless body has roughly 0.083 m2 of wall, and at k = 3.7 W/m2K that carries 3.7 x 0.083 x 5 = 1.5 W for a 5 C rise, keeping the interior at 40 C. Splices alone add almost nothing; a 15 W supply at 88% efficiency adds 1.8 W and overshoots.
304 or 316L for a box under the eaves?
304 for an inland eave that dries between rains. Go 316L when sea air or winter road-salt mist reaches the soffit: 304 can pit at room temperature under chloride deposits in gasket crevices, and 316L's molybdenum resists that pitting. Chloride stress cracking starts near 60 C (140 F) for both grades, far above anything a floodlight box sees.
