An outdoor box is only as tight as the holes you put in it. Choosing cable glands for outdoor enclosures decides whether a rated box stays dry on a pole or fills with water by spring. This guide covers sizing a gland to the cable, getting an RJ45 plug through, where the cable should enter and how to keep the enclosure rating once the holes are drilled.
How do you choose cable glands for outdoor enclosures?
Choose cable glands for outdoor enclosures by the cable’s outside diameter, so it falls inside the gland’s clamping range, with a thread that matches the hole and a rating at least equal to the enclosure’s. Enter from the bottom with a drip loop, seal the gland to the wall, and plug every unused hole.
What a cable gland does on an outdoor enclosure
A cable gland is a threaded body with a compression seal. Tightening the cap squeezes the seal around the cable jacket, which blocks water and dust and gives strain relief so a tug on the cable does not reach the terminations inside.
Glands are a standardized product. IEC 62444 sets requirements and tests for the construction and performance of cable glands, and covers glands with metric entry threads. The practical message for installers: buy a gland with a published rating and clamping range, not an unmarked fitting.
Size the gland to the cable, not the plug
Every gland lists a clamping range, the smallest and largest cable outside diameter it will seal. The cable has to sit inside that range, and a snug fit seals best; installer forums report that the tighter the cable fits the gasket, the better the water seal.
- Measure the actual cable outside diameter with calipers, or take it from the cable data sheet. Outdoor and shielded Ethernet is often thicker than indoor cable.
- Pick a gland whose range brackets that figure, ideally with the cable near the middle.
- Use one cable per seal. Two cables in a single round seal leave a gap between them. Use a gland with a multi-hole insert instead.
- Read the gland’s rating, often IP67 or IP68 on gland listings, and confirm it at least matches the enclosure.
The common mistake is buying a gland big enough to pass the RJ45 plug. It will often be too big to grip the cable behind it.
Match the thread and seal the wall
Gland threads come in metric (M), PG and NPT forms, and they are not interchangeable. Sizes that look close in two systems are still different threads, so match the gland to the enclosure’s threaded entry or to a drilled hole with a locknut on the inside.
- Drill clean, round holes with a step bit or hole saw, and deburr them so the sealing washer seats flat.
- Fit the sealing washer or O-ring on the outside face, against the wall, not just under the locknut inside.
- Tighten the body first, then the cap, to the maker’s guidance; overtightening can crack plastic bodies.
- Check whether the nut is supplied. One RJ45 gland’s data sheet notes that its matching nut is not included.
Ethernet cable gland options for an RJ45 plug
An Ethernet cable gland has an extra problem: a terminated plug is much wider than the cable. Some equipment manuals say it plainly, that RJ45 connectors do not fit through their glands. There are three ways around it.
| Method | How it works | Best for | Watch for |
|---|---|---|---|
| Cut and re-terminate | Feed bare cable through a standard gland, then fit the plug inside | New runs and field crimping | Cable cannot be pulled back out with the plug on |
| Split-insert gland | Plug passes the open body; a split seal then wraps the cable | Factory patch cords and molded cable | The split must close fully when tightened |
| RJ45 bulkhead gland | Two-part fitting with a jack through the wall; the cord plugs in and seals outside | Gear you disconnect often | Molded boots may not fit; check the rating |
For an idea of what a bulkhead gland data sheet states, one lists an IP67 rating and an M25 x 1.5 mounting thread, and its two-part design lets the cable be connected and disconnected without opening the enclosure. Listings for similar parts warn that an over-molded boot on the patch cord can block it, so a boot-less cord may be needed.
If you re-terminate, see pass-through vs standard RJ45 connectors to choose the plug, and avoid splitting a solid grommet with a knife; it rarely closes as well as a purpose-made split seal.
Waterproof Ethernet cable entry: bottom and drip loops
A gland seals the jacket, but water still follows the cable. A waterproof Ethernet cable entry relies as much on position as on the seal.
- Enter from the bottom. A gland on the top face sits under standing water; one on the side collects runoff. The bottom face drains away from the seal.
- Leave a drip loop. Let the cable dip below the gland before it rises into the box, so water drips off the low point instead of running to the seal.
- Keep glands apart. Leave room to get a wrench on each cap, and do not crowd them along an edge where the wall flexes.
- Use outdoor-rated cable. A gland cannot help a jacket that cracks in sunlight; see Cat5e vs Cat6 for camera and PoE runs for outdoor cable choices.
Keeping the NEMA or IP rating
A rating on the box is not a rating on the finished installation. NEMA’s summary of NEMA enclosure types says each type protects against its listed conditions when the enclosure is completely and properly installed. Every hole you drill is part of that installation.
- Use glands, plugs and vents rated at least to the enclosure’s type or IP code.
- Close every unused knockout or spare gland with a rated sealing plug.
- Do not add holes the drawings did not plan for, such as a quick hole for one more camera cable.
- Expect condensation in any sealed box; a gland keeps rain out but cannot stop moisture forming inside.
What each NEMA type and IP code means, and why 4X and IP66 are not the same, is set out in our NEMA enclosure ratings guide. Venting, heat and condensation are covered in choosing an outdoor network cabinet.
Inspection and service
Seals age outdoors, and glands loosen as cables are pulled and plastic expands and contracts in the sun.
- On each service visit, check every cap is tight and the seal still grips the jacket.
- Look for water marks, corrosion or insects inside the box; they show which entry is leaking.
- Replace a gland that has been opened several times or has a hardened seal, rather than overtightening it.
- When you add a cable, add a gland sized for it, never a second cable through an existing seal.
Camera nodes also need a power plan; see how to power an outdoor security camera.
Where to find enclosures and connectors
The network enclosures category lists indoor and outdoor enclosures, including a medium waterproof enclosure with an Ethernet connector, in the Broadband and WiFi division. Plugs and jacks for re-terminating are in the connectors category.
Dealers in Ohio can work with our Columbus low-voltage distributor branch. For pricing and availability, ask your sales representative through the Bursma contact page, or open a Bursma dealer account.
Frequently asked questions
Can an RJ45 plug fit through a cable gland?
Only through a gland too large to seal the cable behind it. Re-terminate after the gland, use a split-insert gland, or use an RJ45 bulkhead gland.
What size cable gland do I need for Cat6?
Measure the cable’s outside diameter and choose a gland whose clamping range includes it. Cat6 jackets vary by type, so check the cable you are actually using.
Should cables enter an outdoor enclosure from the bottom?
Yes, wherever the box allows it. Bottom entry with a drip loop keeps water running away from the seal.
Does drilling a hole void the NEMA rating?
The rating depends on a complete and proper installation. A hole fitted with a correctly rated gland or plug keeps it; an open or poorly sealed hole does not.