Conduit Boxes & Accessories

Conduit boxes and bodies are the access points in a wiring run. They serve as junction, termination, or access points for wiring within metal or PVC conduit runs. The conduit protects the wire. The box or body is where the run turns, splits, terminates, or opens up for a future pull.

The buying decision comes down to two things. Material — PVC or metal. And type — the letter code that tells you how the wire enters and exits. Get both right for the environment and the wiring path, and the install passes inspection and lasts. Get them wrong, and you’re looking at corrosion, failed grounds, or a callback.

Here’s how a conduit body earns its keep. The conduit body acts as a joint, allowing the raceway to bend and project in a different direction. An electrician feeds wire through a hole on one end and out of another. Each type features a removable cover that allows the electrician to more easily access and feed electrical wires. A gasket between the cover and the body prevents moisture from entering. That gasket matters in Montana, where wet springs and wind-driven rain find every weak seal.

Reading the Letter Codes — LB, T, LL, LR, and the Rest

The codes aren’t random. Each conduit body falls into a category depending on two factors — its shape and the location of its removable plate. Conduit body type descriptions include one or two letters. The first letter describes its shape. The second letter describes the direction the wire exits relative to its entry point.

Six common types cover most jobs. Here’s what each one does.

Type	Shape & Function
LR	Forms an L shape that allows a 90-degree turn. Wire enters the top hub and exits a second hub on the right, redirecting along the same plane.
LL	90-degree turn with the exit point on the left side. Wire feeds from the top and out to the left.
LB	Right angle with two hubs. The access point is on the back, opposite the cover. Often used to route wires through a wall — outside of a structure through to the inside.
T	Two hubs that mirror each other plus one at 90 degrees. Merges wires from two locations or routes from one source to two.
X	Four hubs in two parallel sets. Creates a juncture for four separate raceways.
Type C	Connects two conduits in a straight line. Doesn’t change direction, but the removable plate creates a serviceable point along the run.

The LB is the workhorse for getting power from an outdoor meter or panel through the wall to the inside. Western Building Center’s stock list runs the common access bodies — LB in 1/2”, 3/4”, 1”, 1.25”, and 1.5”; LL in 3/4”; and T bodies in 1/2”, 3/4”, and 1.25”. That covers the bread-and-butter residential and light-commercial sizes.

PVC vs. Metal — The Decision That Drives Everything

This is the call that matters most. Pick by environment, not by habit.

Electrical conduit serves one purpose: protect the wiring. But the two materials protect differently. PVC conduit resists corrosion and moisture. Metal conduit resists heat, impact, and fire.

PVC is the answer for anything wet, buried, or corrosive. PVC (polyvinyl chloride) conduit is commonly used outdoors and underground. Its strengths line up with Montana property work: light, fast to cut, and won’t rust — the standard pick for trenching out to a detached garage. The trade-offs are real, though. Always use expansion couplings outdoors. PVC expands and contracts with temperature swings more than most people realize. That’s not a footnote here — it’s the headline. With Montana’s temperature range, long outdoor runs move. And PVC softens in heat, becomes brittle in freezing temperatures — handle it carefully on a cold install day.

One more PVC catch worth planning for. It doesn’t require conduit grounding — but that’s because it has no inherent grounding capability, which requires the installation of a separate equipment grounding conductor, increasing the conductor count. You pull an extra ground wire. Budget for it.

Metal earns its place inside and anywhere the conduit takes abuse. Metal conduit is stronger and more protective than PVC. It’s the go-to in commercial settings and many finished interior spaces. The big advantage: integrated grounding capability allows the conduit itself to serve as the equipment grounding conductor. One less wire to pull. Add fire resistance, excellent mechanical protection, and the ability to stand up to impact, rodents, and UV exposure.

For aboveground commercial, the choice may be made for you. OSHA requires metal conduits for aboveground commercial environments.

Feature	PVC	Metal (EMT/RMC)
Material cost	Lower	Higher
Fire rating	Not fire-rated	Fire-resistant
Corrosion resistance	Excellent	Moderate (needs protection)
Weight	Lightweight	Heavier
Grounding	Needs ground wire	Conduit can serve as ground
UV resistance	Weak unless rated	Strong
Best for	Wet, underground, outdoor	Indoor, high-traffic

Plenty of jobs use both. Many pros run PVC underground, then switch to EMT or RMC above ground using rated transition fittings. It meets code, cuts costs, and gets the job done right.

Matching the Box to the Conduit System

Boxes and bodies aren’t universal. The hub and fitting type has to match the conduit you’re running.

On the metal side, the connection method depends on the conduit. RMC is the heaviest-duty, IMC is slightly thinner, and EMT is the lightest and most common in commercial work. They are joined with threaded couplings (RMC/IMC) or set-screw/compression fittings (EMT). EMT never gets threaded — no bushing is required with EMT and the other thin-wall raceways, but those are not allowed to be threaded. Metal conduit bodies follow the same logic: their holes are either threaded or unthreaded hubs. Threaded hubs let you screw the conduit into the body. Unthreaded hubs feature a set screw that tightens to hold the conduit.

PVC bodies join differently. There are PVC conduit bodies for PVC conduits. Some feature threaded hubs, while others require glue to bind the conduit to the body. The glued joint is permanent — PVC is assembled using solvent cement, creating a continuous, sealed raceway.

Don’t mix metal types and expect the fittings to swap. Each type of metal raceway and its associated fittings must be listed. None of them is interchangeable among types.

Can you put a metal box on PVC conduit? Yes, with the right adapter. Use a suitable fitting, such as a PVC-to-metal conduit connector, for a secure, code-compliant connection. The metal box must be properly grounded — typically by connecting the grounding conductor to the box — and the joint must be sealed against moisture, especially in outdoor or damp locations.

Box Ratings for Wet, Dusty, and Corrosive Spots

For farm, ranch, and outdoor work, the NEMA rating tells you whether an enclosure survives the conditions. Non-metallic PVC junction boxes carry a broad range of them. The Scepter JBox is one example — NEMA rated 1, 2, 3R, 4, 4X, 6, 6P, 12, 13 and certified to UL50/50E by a Nationally Recognized Testing Laboratory.

Why non-metallic for these spots? Molded from PVC, it’s durable and resistant to impacts across a wide temperature range and not adversely affected by water or chemicals. Built for corrosive environments, it’s entirely nonmetallic, eliminating corrosion concerns with screws and other metal parts. The cited applications read like a Montana ag punch list: corrosive environments, waste-water treatment facilities, marine and car washes, agricultural, wash-down areas.

The temperature spec matters here. Recommended operating temp runs -40°F to 122°F, with a UL 94V-O flame rating and UL 746C for UV and water exposure. That -40°F floor covers most of what a Montana winter throws at an outbuilding.

For the worst corrosion — and where code demands the strength of metal — PVC-coated rigid conduit systems exist. The PVC-coated, threaded conduit system is specifically designed to prevent corrosive conditions from causing early replacement. These run UL Listed with the PVC coating as the primary corrosion protection, under standards including UL 6 for rigid metal conduit and UL 514B for fittings.

Installation Basics to Plan and Order For

Knowing the rules tells you how many straps to buy and what box volume you need.

Support is the first thing. Secure conduit with straps every 3 to 5 feet and within 3 feet of any box. Support distance varies by raceway — for example, IMC must be secured within 3 ft of each box and every 3 ft along the run. Western Building Center stocks two-hole conduit straps, push-on straps for rigid and IMC, and multi-packs for bigger jobs — count your run length before you head to the counter.

Bends have a hard ceiling. The total of bends, including offsets, between pull points cannot exceed 360°. Exceed that and you’ll fight the pull — or fail inspection.

Box fill is the one people skip. The number of conductors cannot exceed the percentage fill specified in Chapter 9, Table 1. Overstuff a box and you’ve built a heat trap. Size the box to the wire count and gauge before you buy.

A few field habits that save grief. Use PVC primer and cement for permanent, watertight plastic joints. Always use a draw wire or fish tape for pulling cables, and apply lubricant for long runs with multiple bends to prevent insulation damage. And think about access before you mount anything — position the cover so it’s still reachable after the wall’s closed up and the gear’s in place.

Frequently Asked Questions

What’s the difference between an LB and an LL conduit body? Both make a 90-degree turn. The LL turns and exits to the left on the same plane. The LB also forms a right angle with two hubs, but its access point is on the back, opposite the cover — which is why it’s the common choice for routing wires from outside a structure through the wall to the inside.

Is PVC or metal the right call for a buried run to a shop or barn? For direct burial, PVC is the standard. PVC conduit is the standard choice for underground installations because it’s inherently corrosion-resistant and approved for direct burial. In residential and light commercial projects, it’s typically installed at a minimum depth of 18 inches to protect conductors from environmental exposure and physical damage. Plan on pulling a separate ground wire, since PVC can’t serve as the equipment grounding conductor.

Does PVC conduit connect to a metal box? Yes, with the correct fitting. Use a PVC-to-metal conduit connector for a code-compliant connection, ground the metal box properly, and seal the connection against moisture — especially in outdoor or damp locations.

Why do PVC runs need expansion couplings outdoors? Temperature swing. PVC softens in heat and becomes brittle in freezing temperatures, and it expands and contracts with temperature swings more than most people realize — so always use expansion couplings outdoors. With Montana’s range, a long exposed run without them will work itself loose or crack.

Which NEMA rating fits an agricultural or wash-down box? For corrosive and wet-down settings, a non-metallic PVC junction box covers it. Boxes rated through NEMA 4X and certified to UL50/50E are built for corrosive environments, agricultural use, and wash-down areas — and the nonmetallic build sidesteps the rust problems untreated metal hardware runs into.

How many bends go in a run before a pull point is required? The total of bends, including offsets, between pull points cannot exceed 360 degrees. Plan a body or box as an access point before you hit that limit on a long or twisting run.