3/4" PVC conduit to a NEMA 4 box
For 3/4" PVC into a NEMA 4 / 4X enclosure: thread a Carlon E943E male terminal adapter into a Myers ST2 watertight hub. Punch the hole with a 3/4" conduit-size knockout punch, which cuts a 1.12 in (28.3 mm) hole.
Option A for 3/4": watertight hub (keeps the NEMA 4 rating)
The hub mounts through the box wall with a captive O-ring on the outside face and its own locknut inside. The 3/4" male adapter threads into the hub, and the conduit is glued into the adapter. The O-ring is what keeps the NEMA 4 / 4X rating.
Order list: 3/4", Option A
| Size | Qty | Part | Mfr # | Notes |
|---|---|---|---|---|
| 3/4" | 1 | 3/4" PVC male terminal adapter | Carlon E943E | Glue the conduit into it. Male thread goes into the hub. |
| 3/4" | 1 | 3/4" watertight hub, zinc | Myers ST2 | Crouse-Hinds (Eaton) Scru-Tite. Captive O-ring, insulated throat. |
| or, instead of the ST2: | ||||
| 3/4" | 1 | 3/4" watertight hub, aluminum | Myers STA2 | Aluminum version of the ST2. |
| 3/4" | 1 | 3/4" watertight hub | Appleton HUB75A | Die-cast aluminum, integral O-ring, insulated throat. |
| 3/4" | — | PVC primer + solvent cement | any listed | Rated for 3/4" conduit. |
Option B for 3/4": sealing locknut (raintight only)
The adapter goes through the hole from outside. The sealing locknut goes on the outside face and a standard 3/4" locknut on the inside. Bridgeport lists these as raintight, with no watertight or NEMA 4 claim. If the box has to stay NEMA 4, use Option A.
| Size | Qty | Part | Mfr # | Notes |
|---|---|---|---|---|
| 3/4" | 1 | 3/4" PVC male terminal adapter | Carlon E943E | Same adapter as Option A. |
| 3/4" | 1 | 3/4" sealing locknut | Bridgeport 142 | Steel with a PVC seal. "Provides raintight seal." |
| 3/4" | 1 | 3/4" standard locknut (inside) | any listed | Plain, not sealing. |
Hole size for 3/4"
Use the 3/4" conduit-size knockout punch (Greenlee K3P-3/4). It cuts a 1.12 in / 28.3 mm hole.
Knockout punches are labeled by the conduit size they're for, not by the hole they cut. A punch labeled with the hole diameter is a different tool.
Install steps for 3/4"
- Pick the entry. Use the bottom or a side. A top entry collects water against the seal.
- Punch the hole with the 3/4" conduit-size punch (1.12 in). Deburr both faces so the O-ring sits flat.
- Mount the Myers ST2 from outside with the O-ring against the outside face. Tighten the hub locknut from inside until the O-ring is evenly compressed. On fiberglass or polycarbonate boxes, stop at firm.
- Thread the Carlon E943E into the hub until it's snug. Don't crank on PVC threads. If you use thread sealant, pick one that's rated safe for PVC.
- Glue the 3/4" conduit into the adapter socket. Cut square, deburr, then prime and cement both surfaces. Push it fully home with a quarter turn and hold it for the cement's set time.
- Support it within 3 ft of the box and at no more than 3 ft spacing (NEC Table 352.30 for 3/4"; check your code edition).
- Check that the O-ring is evenly squeezed all the way around. If your equipment ground lands in this box, bond the hub's grounding screw.
Don't grab the neighboring size
The next size up and down use part numbers one step away. These are not for 3/4" conduit:
| Size | Adapter | Myers hub | Sealing locknut | |
|---|---|---|---|---|
| 1/2" | One size smaller | E943D | ST1 | 141 |
| 1" | One size larger | E943F | ST3 | 143 |
Also don't confuse Carlon E943 (male terminal adapter) with E942 (female adapter). At 2", for example, E942J is the female adapter.