Short answer: yes. A receptacle outdoors is a damp or wet location, and the NEC has required weather-resistant receptacles there since its 2006 edition. Fit a weather-resistant GFCI rated 15 A, 120 V, and where rain or splash can reach the face, add a while-in-use cover over it. The difference is hardware, not electronics: a WR unit carries nickel-plated contacts and a nickel-plated mounting strap, where a standard unit uses plated steel that rusts through in a season or two of damp. That corrosion is what tripped your old 15 A unit and left it stuck off, and the box and cover decide the rest.
What weather resistant means on the device
A weather-resistant receptacle is a standard 15 A or 20 A device rebuilt for outdoor duty and marked WR. The marking rides on UL 498, the safety standard for receptacles, and adds corrosion and ultraviolet-weathering tests that a standard device never takes. Inside, the contacts and the mounting strap come nickel-plated to fight corrosion; the terminal and mounting screws are corrosion-resistant grades too. The trip electronics stay the same: a US Class A GFCI, standard or WR, trips on an imbalance of 4-6 mA between the current going out and the current coming back. IEC countries set the equivalent personal-protection level at 30 mA for their RCDs, so the WR label buys you the same trip in hardware built to survive the weather.
The code minimum arrives with the 2006 NEC edition, which made WR the required receptacle type in damp and wet locations. Anything you mount outdoors, covered or not, is one or the other.
Why the old unit trips and will not reset
Water reaches the electronics two ways: splash behind a flat cover, and condensation cycling inside a box that breathes. Wet-dry cycles rust the plated strap and screws, and a moisture film tracks across the board. The GFCI sensor compares the current leaving on the line conductor with the current returning on the neutral; leakage that skips the return looks exactly like a ground fault. Once damp leakage reaches the trip band, the unit trips, and because the leak never clears, the reset will not hold. Trip-and-won't-reset on an outdoor unit means corrosion until you prove otherwise.
Worked example, with illustrative values: at 120 V, model the damp film as a 24,000 Ω resistor from the line side to the grounded strap, downstream of the sensor. I = V/R = 120 V / 24,000 Ω = 0.005 A = 5 mA. That sits mid-band in the 4-6 mA Class A window, so the coil trips and stays tripped. The band edges bracket the film: 30,000 Ω leaks 4.0 mA, right at the trip point, and 20,000 Ω leaks 6.0 mA. A patch of damp contamination a few centimetres across presents 20-30 kΩ easily. Replace the unit, and kill the breaker and confirm the box is dead before you pull it. A corroded GFCI is scrap, not a drying project.
What the WR tests leave to the box and cover
WR qualifies the device, not the installation. The corrosion and weathering tests cover the contacts, strap, screws and face; water running into the wiring compartment is nobody's device test. In a wet location the NEC requires the enclosure to stay weatherproof with the plug inserted, which is the working definition of a while-in-use cover. Mount the cover with its gasket seated on clean, dry metal, and leave the cord loop inside the cover as designed. A WR device behind a flat, un-gasketed cover in the rain dies the same way the standard one did: the box, the cover and the gasket carry the water rating between them.
Pick the box and cover for the location
| Where the box sits | Location class | Box and cover | Device on the wall |
|---|---|---|---|
| Exposed to rain, splash or hose; pool deck | Wet | Gasketed metal box, while-in-use cover | WR GFCI, or a WR receptacle on an upstream GFCI |
| Covered porch or soffit, open sides | Damp | Weatherproof box, gasketed flat cover | WR device |
| Dry interior wall | Dry | Any listed box | Standard device |
The NEC lists which enclosure types suit which conditions in Table 110.28, and NEC 110.28 adds that an IP code cannot replace an enclosure type rating on a US installation. For the fundamentals behind that table, the outdoor enclosures guide and the NEMA 3R vs NEMA 4 guide lay out the choices by weather and corrosion. Around a pool, chloride-laden splash puts corrosion in play, and a Type 4X box earns its keep: NEMA 250's corrosion table gives Type 4X 200 hours of salt spray against an AISI 304 stainless specimen.
Give condensation somewhere to go as well; 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, so fit any drain at the low point and face it down. Every enclosure type on a catalog page is a manufacturer rating; the stainless boxes we build are rated NEMA 4X / IP66 by the manufacturer and not UL listed.
Fasten the box with stainless screws. The plated screws from the junk drawer rust to the metal within a season and strip the threads you just fixed; mounting screws through an outdoor enclosure without leaks covers screw choice and sealing. Keep the 1/2 in EMT and the box in the fault path: the grounding and bonding guide covers bonding the raceway so a fault clears fast. A GFCI trips on imbalance and works even where the box carries no equipment ground; what changes is how you land the load-side conductors.
Poolside rules go further
A receptacle near a pool answers to the NEC's swimming-pool article, and its limits sit tighter than the ordinary outdoor ones. Keep the box at least 5 ft (1.5 m) from the inside wall of the pool, measured to the water, not the deck edge. A pump receptacle in that zone needs GFCI protection, a locking-type plug, and a cord no longer than 3 ft (0.9 m). Pool splash carries chlorides, and 304 stainless can pit at room temperature under chloride deposits, so 316L is the sane grade for metal at deck level; the same chemistry is why wet-dry cycling rusts 316L stainless outdoors. If the old box sits inside that line, move the new one back while the conduit is open.
What goes on the order
- One 15 A, 120 V weather-resistant GFCI, Class A trip at 4-6 mA, or a WR receptacle when the GFCI moves upstream indoors.
- One while-in-use cover for wet locations, matched to the device footprint, with its gasket intact.
- One gasketed metal box listed for wet locations, with a 3-6 mm drainage opening at the low point, facing down.
- Stainless mounting screws, plus a weatherproof hub where the 1/2 in EMT enters the box.
- For the pump circuit: a locking-type WR receptacle, a cord of 3 ft or less, and the box 5 ft or more from the water.
- Put the GFCI reset where you reach it dry: feeding the outdoor run from an indoor panel moves the test button out of the rain.
When the GFCI rides inside a control panel instead of a wall box, device choice and wiring follow panel rules. If the panel or HMI feeding this circuit lives outside too, the same logic scales up: a 316L stainless enclosure rated NEMA 4X by the manufacturer keeps drives dry the way WR hardware keeps a receptacle alive, and custom stainless enclosures let you set every cutout for the device, hubs and conduit. The decision, stated once: outdoors means WR hardware, a cover that works with the plug in, and a box that drains.
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 | 316L stainless | 16 x 12 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 20 × 16 × 8 in | 316L stainless | 20 x 16 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 24 × 20 × 8 in | 316L stainless | 24 x 20 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 12 × 10 × 6 in | 316L stainless | 12 x 10 x 6 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
Does a covered outdoor receptacle still need a weather-resistant GFCI?
Yes. A covered porch or soffit is a damp location, and the NEC has required weather-resistant receptacles in damp and wet locations since its 2006 edition. The cover only shields the face; the strap and contacts still sit in damp air, and plated steel corrodes within a season or two. Fit the WR unit in a gasketed box with stainless screws, and keep the flat weatherproof cover closed whenever nothing is plugged in.
Why did the old GFCI trip and then refuse to reset?
Damp left a permanent leakage path on the electronics. At 120 V, a 24 kΩ moisture film leaks 5 mA (120 V / 24,000 Ω = 0.005 A), inside the 4-6 mA Class A trip band, so the sensor reads a constant fault and holds the mechanism open. Rust on the strap and screws confirms the water history. Replace the unit; drying a corroded GFCI rarely restores a trip you can trust.
Can the GFCI sit indoors with the outdoor receptacle downstream?
Yes, and for a pool-side circuit it is the cleaner build. Feed the outdoor run from a GFCI in the dry panel; the same 4-6 mA trip protects everything downstream. The outdoor device still has to be weather resistant, because that rule follows the location, and a wet location still needs the while-in-use cover. You also gain a reset button you can reach without standing in the rain.
How close to a pool can the receptacle sit?
At least 5 ft (1.5 m), measured from the inside wall of the pool to the box, so measure to the water and not the deck edge. The NEC's pool rules add GFCI protection, a locking-type plug on a pump receptacle and a pump cord no longer than 3 ft (0.9 m). Move the box back now while the conduit is already open.
Is the while-in-use cover needed under a deck lip?
If rain, splash or hose water can reach the face, treat it as a wet location and fit the while-in-use cover; the NEC wants the enclosure weatherproof with the plug inserted, which is exactly what its spring-loaded lids do. A flat gasketed cover is the damp-location answer for a spot where the plug stays out and the lid closes over an empty face.
