Conduit Connectors

The single most useful thing to know before grabbing a conduit connector: the conduit type decides the fitting. Not the other way around. EMT requires set screw or compression connectors. Rigid metallic conduits pair with threaded steel or aluminum fittings. IMC works in tandem with threaded fittings similar to rigid ones. PVC requires solvent-cement or threaded adapters. Liquid-tight conduit requires gasketed fittings to ensure a sealed system.

For broader project planning, explore WBC’s building materials resources.

Grab the wrong one and the joint won’t seat, the inspector flags it, or worse — the connection loses grounding continuity. Never mix incompatible fittings or force threads to “almost” work.

A connector does one job, and it does it everywhere conduit meets a box, panel, or another length of pipe. Connectors attach conduit to boxes, enclosures or panels for secure terminations. The environment — dry, wet, or corrosive — then narrows down which version of that connector you actually need.

Matching the Connector to the Conduit Type

Every conduit family connects a different way. Here’s how they break down.

Conduit Type	Connection Method	Typical Material
EMT	Set-screw or compression	Zinc die-cast or aluminum
RMC / IMC	Threaded, with lockrings and ground bushings	Steel or aluminum
PVC	Solvent-cement or threaded adapters	PVC
Flexible metal (FMC)	Screw-on connector with locknut and bushing	Steel
Liquid-tight	Gasketed connector	Nickel-plated brass, zinc, coated steel

EMT. This thin-walled conduit is easy to install, flexible, cost-efficient, and lighter than other types. Its bendability means workers can use hand tools to maneuver it into tight spaces. One drawback is that workers need fittings and couplings, like compression fittings and set screws, to connect pieces together. For a box entry, insert the conduit into the connector until it bottoms out, tighten the set screw or compression nut securely, then install the fitting into a junction box and secure it with a locknut and plastic bushing on the inside to protect the wire.

RMC and IMC. The heavy-duty end of the metal lineup. Rigid metal conduit is typically threaded. When you connect it, thread the conduit into a coupling or connector by hand, then tighten with a pipe wrench. Always use threaded lockrings and ground bushings for connections into metal boxes.

PVC. The residential and underground workhorse. PVC conduit is a non-metallic, affordable, and corrosion-resistant material. It’s easy to work with, especially for outdoor and underground installs — shed power feeds or landscape lighting. No set screws, no threading on the standard run. Solvent cement does the work.

Flexible metal. Used when routing around obstacles or where vibration is a concern, flexible metal conduit is a good choice for tight spaces or short connections to equipment. It uses screw-on connectors with a locknut and bushing. One caution: the interlocking bands leave FMC susceptible to moisture if improperly prepped, and the bands also have sharp edges, so installers should be careful to avoid damaging wires.

Choosing by Environment — Dry, Wet, and Corrosive

The same conduit can call for a different fitting depending on where it lives. This is where buyers go wrong.

Dry and indoor. Set-screw connectors made from zinc die-cast or steel are used with EMT conduits in dry locations. Simple, cheap, fine for a garage or unfinished basement wall.

Wet and outdoor. Look at the label before you buy. When installing steel raceways below grade, in concrete slabs, in direct contact with the earth, and in locations subject to saturation with water, it’s considered a “Wet Location.” Look for the package or label to state “Wet Locations” and listed to UL 514B. Sometimes the package may say “Raintight” instead of “Wet Locations.” For EMT in those spots, compression connectors made of galvanized steel, aluminum or nickel-plated brass provide a vibration-resistant seal and a watertight connection used indoors and outdoors. For flexible runs in wet areas, liquid-tight conduit fittings constructed from galvanized steel, PVC, aluminum or stainless steel are best suited for wet or hazardous settings to prevent moisture ingress.

Corrosive. Wet locations require liquid-tight or PVC-coated fittings to prevent moisture intrusion, while corrosive environments require stainless steel or PVC-coated fittings to protect connections from chemical reaction damage.

Concrete. A separate listing applies here. Encasement of steel raceways in concrete requires that the fittings being used are listed as concrete-tight. Compression-type fittings are concrete-tight if listed to the standards. Set screw fittings may be required to be taped to be concrete-tight — in which case the package will state “Concrete-tight when taped” or similar wording.

For Montana exposed runs, material choice matters more than most buyers expect. PVC loses strength in high heat and can become brittle in extreme cold. Its code-listed ambient max is 122°F. In high-swing climates, use expansion fittings — required when runs exceed 25 feet and temperature change exceeds 60°F. Metal handles the swing better: PVC’s temperature range runs -4°F to 122°F ambient, while metal conduit handles -40°F to 140°F and beyond. And for any above-ground run in the sun, use sunlight-resistant UV-rated PVC. Basic white PVC will chalk, embrittle, and crack if left exposed.

Sizing, Support, and Grounding

Three places installs go sideways: wrong trade size, sloppy support, broken grounding.

Size. Match the trade size exactly. When in doubt on a wire pull, oversize one trade size up — it eases wire pulls and supports future upgrades.

Support. For steel raceways, the NEC requires that conduit and tubing be supported every 10 feet and securely fastened within 3 feet from every outlet box, junction box, device box, cabinet, conduit body, or other termination. Improper securement can put extra strain on the fitting, possibly leading to premature failure. PVC needs more babysitting: max 3 ft support spacing for ½–1” PVC.

Grounding. This is the quiet one that fails inspections. One of the major benefits of steel raceways is that they can be used as an equipment grounding conductor. Because of that, all fittings and connectors must pass a resistance and continuity test to confirm they can provide an effective ground-fault current path, to receive a listing under UL 514B. Tightening to spec is part of that path — for example, a ½ trade size compression fitting is tightened to 300 lbf-in.

Joining PVC to Metal Conduit

Common scenario on Montana properties: a run comes out of an exterior box, drops below grade, and you want metal above ground for looks or protection. You can join the two — with the right adapter.

Use threaded adapters for each and screw together — for example, a female PVC adapter and a male EMT adapter. A field tip worth following: use a male threaded fitting on the PVC and a threaded female coupling on the steel. Thread plastic into metal to prevent cracks in the plastic. Outdoors, use listed transition fittings with gaskets and sealant to maintain water-tightness and bonding continuity.

Don’t skip the bonding. When adding metal conduit to a nonmetallic system, ensure the metal conduit is bonded to the equipment grounding conductor.

And the rule that saves a wire job: do not put any glue on the conduit or attempt to use glue while the cable is in place — the glue will destroy the insulation of the cable. Pull the conductors out before working on the conduit.

PVC Solvent-Weld Basics

PVC connections are unforgiving once set, so the prep matters. Deburr both ends with a reamer or file — sharp edges can damage wires. Test-fit your connectors before installing. For PVC, use a dedicated PVC cutter and dry-fit before applying glue. Solvent-welded fittings bond quickly — mistakes are hard to undo.

The actual weld: apply PVC primer, then solvent cement to both the fitting and conduit. Push and twist the conduit into the fitting in one smooth motion. Hold it in place for 10–15 seconds until it sets.

On schedule, two grades cover most jobs. Schedule 80 has a thicker wall and is more difficult to bend, though the thinner Schedule 40 conduit is more flexible. For buried runs, Schedule 40 is approved for direct burial. Watch local rules on exposed work, though — some municipalities require Schedule 80 PVC for exposed areas, while others demand metal for any conduit under 8 feet off the ground. Don’t guess — call your AHJ.

What Western Building Center Carries

The connector lineup covers the main conduit families. For EMT, there are set-screw connectors in sizes including 1-1/4”, a 2” compression connector, and a 1/2” offset set-screw connector, plus a Halex 3/4 In. compression EMT connector in a 5-pack.

For liquid-tight and flexible runs, the selection runs 1/2” and 3/4” zinc liquid-tight connectors, a 3/4” zinc liquid-tight 90° connector, non-metallic 1/2” and 3/4” liquid-tight connectors, and non-metallic 1/2” and 3/4” 90° connectors. Armored cable connectors include Halex 3/8 In. set-screw and straight-squeeze armored cable/conduit connectors. Rigid hardware covers rigid conduit locknuts in 1”, 1-1/2”, and 2” sizes.

Frequently Asked Questions

Can I connect PVC conduit directly to metal conduit? Yes. Use threaded adapters on each — a female PVC adapter screwed to a male metal adapter is one common pairing. Thread the plastic into the metal rather than the reverse, which reduces the chance of cracking the PVC. Outdoors, use listed transition fittings with gaskets and sealant for water-tightness, and bond the metal section to the equipment grounding conductor.

Set-screw or compression for EMT — which one? Set-screw connectors made from zinc die-cast or steel work for EMT in dry, indoor locations. Compression connectors give a vibration-resistant, watertight seal and are the pick for wet or outdoor spots. For a wet location, confirm the package reads “Wet Locations” or “Raintight” and carries the UL 514B listing.

Why does my metal connector need to pass a grounding test? Steel raceway can serve as the equipment grounding conductor itself. For that ground-fault path to work, every fitting and connector has to maintain continuity — which is why listed metal fittings pass resistance and continuity testing under UL 514B. Tighten each one to the manufacturer’s spec so the path stays intact.

How far apart do I support conduit? Steel conduit and tubing get supported every 10 feet and fastened within 3 feet of every box or termination. PVC in the ½–1” range needs support at least every 3 feet. Loose runs strain the fittings and can cause premature failure.

Do I need expansion fittings on an outdoor PVC run? On long runs with big temperature swings, yes. Expansion fittings are called for when a run exceeds 25 feet and the temperature change exceeds 60°F — a real concern given how far Montana temperatures travel between seasons. Allow about 3/8 inch of movement per 10 feet for every 100°F differential.

Can I glue a PVC fitting with the wires already inside? No. Solvent cement destroys wire insulation. Pull the conductors out before you cut, prime, or glue any part of the run.