Yes — your side entries need the same sealing as a top entry. On a pull box, NEC 314.15 governs: in damp or wet locations, boxes and their fittings have to be placed or equipped so that moisture cannot enter or accumulate inside. Double locknuts on rigid conduit do neither. Swap the outer locknut on each run for a sealing locknut listed for wet locations, or re-make the entry with a gasketed threaded hub, keep your splices above the lowest entry, and open a 3–6 mm [1/8–1/4 in] drain at the low corner. The plain-locknut relief belongs to cabinets and meter socket enclosures under NEC Article 312, where locknuts below the live parts are accepted. A pull box has no live parts, so the relief never arrives.
What the box rules say
NEC 314.15 is the sentence that settles your box. In damp or wet locations, boxes, conduit bodies and fittings are placed or equipped so that moisture stays out of the box, and an outdoor box on a wall is a wet location under the NEC. The word doing the work is equipped: every conduit entry needs a fitting that seals at the enclosure wall.
For rigid and intermediate metal conduit, that fitting is a threaded hub with a gasketed flange — a Myers-type hub in trade language — or a sealing locknut listed for wet locations. For EMT it is a raintight connector with the same listing. A plain locknut is a good clamp and a good bond; its teeth bite the wall and carry the raceway grounding path. It has no gasket, though, so rain on the fitting and water travelling down the conduit both follow the threads inside. Two locknuts double the clamp, and neither one seals. For the top-entry version of the question, the conduit hub vs sealing locknut comparison for top entries works the choice in detail. On a pull box the rule is the same on every face.
Where the below-live-parts reading fits
NEC Article 312 covers cabinets, cutout boxes and meter socket enclosures, and its wet-location scheme is built on managed water. Anything that gets in must sit below the live parts and drain out, and the conductors are wet-rated anyway. Under that scheme, a raceway entering an outdoor 3R cabinet below the live parts keeps its plain locknuts. Every entry above the live parts must be sealed — a meter socket is the textbook case.
A pull box is none of those enclosures, and that is where your shortcut breaks. Under the box rules there is no live-parts line to stay below, because nothing in the box is energized. The relief never switches on, and every entry takes a wet-location fitting. The bottom entry is not a free pass either: conduit outdoors breathes with the day-night cycle, and the condensation it collects runs downhill into the lowest box on the run. That is why a pull box seals the bottom too, and pairs it with a drain.
The water plan inside a 3R box
NEMA 250 describes Type 3R as an outdoor rating: protection against rain, sleet and snow, with the box undamaged by ice forming on it. It says nothing about hose spray, which is the step up to Type 4 — the NEMA 3R vs Type 4 guide lays out the difference and the tests behind it.
So a 3R box manages water rather than promising you a dry interior. Factory knockouts are the norm on 3R cabinets up to about 24 in [610 mm] wide, and they sit low on the sides and the bottom. A top opening takes a gasketed hub or a listed closing plate; a top knockout knocked out and fitted with plain locknuts is the leakiest entry the box can carry. Inside, splices and devices sit above the water line, the conductors are wet-rated insulation such as THWN-2, and a 3–6 mm [1/8–1/4 in] drain opening at the lowest corner lets the water out. NEC 314.15 permits exactly that opening in boxes listed for damp or wet locations; check the edition your authority having jurisdiction enforces.
Keep your geometry even with sealed fittings, because the conduit keeps delivering water. Water backing up a conduit run into a low box is the failure mode on long outdoor runs. A drain tee on a vertical riser takes most of that water out before the box ever sees it. Keep the label honest too: a NEMA 250 type on the door is the manufacturer's rating — ours are manufacturer-rated and not UL listed — while NEC 110.28 requires covered equipment to carry its type marking, and Table 110.28 lists 3R among the outdoor types.
Worked example: three entries in a 12 x 12 x 6 box
Say the box on the wall is a 12 x 12 x 6 in [305 x 305 x 152 mm] pull box with two 2 in RMC entries on the sides and a 1 1/2 in RMC out of the bottom, carrying 10 AWG THWN-2 with splices. Put the side knockouts 2 in [51 mm] above the floor, the way factory layouts sit them. A 2 in rigid fitting spans about 2.375 in [60 mm] outside, so the top of the entry lands 2 + 1.2 = 3.2 in [81 mm] above the floor. Land every splice above that line and you keep 12 - 3.2 = 8.8 in [224 mm] of usable splice zone on the wall.
Then seal all three entries: sealing locknuts on the side runs, a hub or a sealing locknut on the bottom, and one 3 mm [1/8 in] drain hole at the low corner. Water arriving down the riser now meets a sealed entry and leaves through the drain before it reaches a conductor. The same arithmetic sizes the splice zone on any box height.
Fixing entries already made with locknuts
The box is already cut and threaded, so work with it: each entry takes one part, and the conduit stays put. Lock the circuits out and prove them dead with a tested meter first; a pull box has no source of its own, but its conduits can be live.
- Back the outer plain locknut off each side entry. Leave the inner locknut in place — it carries the clamp and the bond to the wall.
- Thread a sealing locknut listed for wet locations onto the conduit, gasket toward the box, and tighten it against the wall.
- Where you would rather have a hub, break the entry and fit a threaded hub; make the conduit up wrench-tight into it. Hub thread and size compatibility on outdoor boxes keeps the sizes straight.
- Move any splice that sits below the top of the lowest entry.
- Drill the 3 mm [1/8 in] drain at the lowest corner, on a box listed for damp or wet locations.
When you are done, pour water over the entries the way heavy rain would hit them, then open the door: dry wall, dry splices, and the water gone through the drain. For the wider sweep of an outdoor cabinet that has been leaking for a season, the unsealed-entry repair checklist walks the whole box.
What to order next time
If the site washes this box down, sits coastal, or the runs collect condensation, stop managing water and specify it out. A Type 4X body with factory-cut entries arrives sealed and stays sealed. We build 316L wall-mount enclosures rated NEMA 4X / IP66 by the manufacturer, not UL listed, with your hub holes punched where the drawing puts them. The custom stainless cutout page lists what to send. Delivery is 10 business days anywhere in the world, counted from your approval of the drawing.
Sized like the worked example, a 12 x 12 x 6 in 316L wall-mount enclosure gives you 11.91 in [302 mm] of clear inside height. That is the same splice zone, with gasketed hub holes instead of field locknuts. Grade matters outdoors: 304 can pit under chloride deposits even at room temperature, so coastal and de-icing spray sites get 316L. Wall-mount sizes run from 6 x 4 x 4 in up to 60 x 36 x 16 in if the panel grows.
| Box you are sealing | What every entry takes |
|---|---|
| Pull or junction box, outdoor, no devices | Wet-location fitting on all of them: gasketed hub or sealing locknut on RMC and IMC, raintight connector on EMT |
| Cabinet or cutout box with live parts, under NEC Article 312 | Plain locknuts accepted below the live parts; seal every entry above them |
| Top opening on a 3R box | Gasketed hub or a listed closing plate |
| Bottom entry on an outdoor box | Wet-location fitting, plus the 3–6 mm [1/8–1/4 in] drain at the low corner |
For the box on your wall today, the first row is the answer: sealing locknuts on both side entries, splices above the entry line, one drain hole at the corner. That puts the installation back where its 3R label says it is — rain stays outside, and whatever the conduit delivers leaves at the bottom.
Enclosures in this article
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 12 × 12 × 6 in | 316L stainless | 12 x 12 x 6 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
Does an EMT connector on a 3R pull box need to be raintight?
Yes. On a pull box every entry is a wet-location entry, and a standard dry-location EMT connector does not provide one. Use a raintight connector listed for wet locations; the gasket is built into its flange, so the seal arrives with the fitting.
Can I seal the locknuts with silicone instead of changing fittings?
Sealant is not a listed wet-location entry, and inspectors read it that way. Silicone skins and shrinks outdoors, and it pulls off painted steel after a few seasons, leaving the same open thread path. A sealing locknut listed for wet locations fits the same knockout and the same conduit, so the fix is one part per entry.
How many drain holes does a 3R pull box need, and what size?
One is enough for a pull box. NEC 314.15 allows 3 mm [1/8 in] as the smallest opening and 6 mm [1/4 in] as the largest, in boxes listed for damp or wet locations. Drill it at the lowest corner, below every entry, so water leaves before it can rise to a splice.
Is a sealing locknut as good as a hub on a pull box entry?
Both are wet-location entries for rigid conduit, so either satisfies the code question. The hub bolts a gasketed flange over the hole, which suits a large or slightly oversize opening and gives a wrench-tight thread for the conduit. The sealing locknut keeps your existing knockout, which makes it the faster fix on a box already built.
Does the rule change if the box also holds a fused disconnect?
It changes shape. A box with a disconnect or other live parts is a cabinet or cutout box under NEC Article 312, where plain locknuts are accepted below the live parts and every entry above them is sealed. With live parts near the top, the bottom entry usually ends up as the only plain one.
