Conduit Bodies Decoded

Three decisions, three tables: which fitting family the area classification allows (the one that matters on industrial work — Form 7/8 gasketed bodies reach into Class I Division 2, only explosionproof condulets serve Division 1), what the letter says about geometry (L turns 90° with the cover at Back/Left/Right; C pulls straight through; T and X branch; E dead-ends), and what the Form number says about the body profile. Plus the splice rules that decide whether a body is a pull point or a junction.

Which family, which location

NEC 501.10(B)(4)

What actually decides body selection on industrial work: where the area classification allows each fitting family. The code line: Division 1 boxes must be suitable for Division 1 (explosionproof, threaded); Division 2 boxes and fittings need not be explosionproof unless they contain arcing or high-temperature devices — which is why the gasketed general-purpose forms qualify there and Form 5 does not appear in the manufacturers' hazardous-location selectors.

What actually decides body selection on industrial work: where the area classification allows each fitting family. The code line: Division 1 boxes must be suitable for Division 1 (explosionproof, threaded); Division 2 boxes and fittings need not be explosionproof unless they contain arcing or high-temperature devices — which is why the gasketed general-purpose forms qualify there and Form 5 does not appear in the manufacturers' hazardous-location selectors.
Family	Unclass.	Class I Div 1	Class I Div 2	The rule behind it
Standard bodies — Form 5Flat screw-cover condulets	✓			Absent from the manufacturer hazardous-location selectors — spec it for unclassified work
Gasketed general-purpose bodies — Form 7, Form 8, Mark 9, mogulsClip- or screw-cover condulets with gaskets; FS/FD boxes ride the same column	✓		✓	Div 2 boxes need not be explosionproof per 501.10(B)(4) — provided no arcing, sparking, or high-temperature device lives inside, in a threaded metal system
Explosionproof bodies & junction boxesGUA / GUB / EAB / EAJ-style condulets with threaded covers; EJB boxes	✓	✓	✓	The only bodies for Division 1. Between a sealing fitting and an explosionproof enclosure, L/T/X shapes may be no larger than the conduit trade size (501.15(A)(1))
Sealing fittingsEYS / EZS-style, compound-filled; combination seal-drains		✓	✓	Wherever 501.15 requires a seal; Division 2 boundary seals need not be explosionproof, only identified for minimizing gas passage
Hazloc cable terminators & cord connectorsTMCX-style for MC-HL/ITC-HL (Div 1); CGB-style (Div 2); EBY factory-sealed cord connectors (both)	✓	✓	✓	Per family — MC-HL terminations are the Div 1 cable path; ordinary listed fittings serve the Div 2 cable types

Class II runs on a different axis: dust-ignitionproof equipment for Division 1, dusttight for Division 2 and Class III — the explosionproof condulet families are typically dual-listed for Class II Division 1, while the Form 7/8 column is a Class I Division 2 designation only. Series names (GUA, EYS, TMCX…) are Crouse-Hinds examples; Appleton, Killark, and others sell listed equivalents — the marking governs.

Body types by letter

Industry standard

Every common conduit body letter with its openings, cover position, and the job it does. Left/right handedness is named viewing the flat back of the body (cover away, through-hub down).
Type	Hubs	Layout	Cover	Where you use it
C	2	Straight through	Front	Pull point mid-run — access without a direction change
E	1	Dead end	Front	End-of-run access; clean transition to equipment or a whip
LB	2	90° turn	Back	THE conduit body — turning into a wall penetration
LL	2	90° turn	Left side	Left-hand turn where a back opening cannot face the pull
LR	2	90° turn	Right side	Right-hand turn, same logic mirrored
T	3	Through run + side tap	Front	Branching a run three ways
TB	3	Through run + side tap	Back	Branch with rear access when the front is blocked
X	4	Four-way cross	Front	Intersection of four runs

Mogul versions of the same letters carry enlarged bodies for the bending space that large conductors require. Every type is also made in explosionproof-rated versions for classified locations — a different listing, not a different letter.

Form profiles

Trade shorthand

The Form number describes the body profile and cover system. It is Crouse-Hinds naming that became de-facto trade shorthand — Appleton sells the same shapes as Unilets, Thomas & Betts as Series 35 — so spec one and expect equivalents to be submitted.
Form	Cover attachment	Body profile	Pick it for
Form 5	Flat covers, screw-attached	Rectangular profile with generous openings; integral rounded bushings, rollers on larger C/LB sizes	Wire-pulling ease and cover access on bigger fills
Form 7	Clip / wedge-nut covers — no cover screws	Compact, rounded profile close to the conduit size	Neat exposed work and fast cover removal
Form 8	Screw-attached covers with gasket	Larger interior volume, flat back	Bigger conductor fills and a tighter gasketed assembly

Materials run copper-free aluminum, Feraloy iron alloy, and stainless by manufacturer; wet locations need the gasketed cover actually installed, not just available.

Pull point or junction box? The 314.16(C) line

A conduit body earns its keep two ways, and the NEC draws a hard line between them. As a pull point or direction change, any body works — that's the default job. To hold splices, taps, or devices, 314.16(C)(2) requires the body to be durably marked with its cubic-inch volume, and the conductor count must clear the same box-fill arithmetic as any outlet box. Bodies enclosing 6 AWG and smaller must have a volume at least equal to the fill calculation of the conductors inside. Short-radius bodies never qualify. And per 314.29 every body stays accessible after installation — buried or tiled-over conduit bodies are their own violation.

Reading an order: what the letters and forms buy you

"LB" solves the single most common routing problem in conduit work — turning 90° through a wall with the pull access facing you — which is why it outsells every other letter combined. The LL/LR pair exists for when the back opening would face the wrong way; T and TB split a run; C gives the code-required pull point on long straight runs without cutting in a box; X crosses two runs, and E finishes one. The Form number then sets the working room: Form 7 hugs the conduit line for clean exposed work with snap-on covers, Form 8 adds interior volume with screwed, gasketed covers, and Form 5's flat rectangular profile with rollers on the big sizes is built for pulling heavy wire.

Common questions

How do I tell an LL from an LR in the field?

The handedness is named from the back of the body — flat mounting face toward you, through-hub down: the side hub and cover of an LL exit left, an LR right. Hold one cover-up in your hand and the turn reads mirrored, which is exactly why the two get swapped on material orders. When in doubt, match the catalog drawing to how the body will actually mount.

Can I splice inside a conduit body?

Only if the body is durably marked with its volume and the conductor fill works out under the 314.16 box-fill math — that is what NEC 314.16(C)(2) requires. Most standard bodies are used as pull points and direction changes; moguls and bodies marked with cubic-inch volume are the ones that legitimately host splices. Short-radius bodies (capped elbows and the like) can never contain splices.

What does a mogul conduit body get me?

Interior room. Mogul versions of the same letters carry an enlarged body that provides the wire-bending space large conductors need — the practical threshold where standard bodies run out is in the 1/0-and-up range, and mogul LBs are the standard fix for getting big feeders around a 90° into a building.

Can I use a Form 7 conduit body in Class I, Division 2?

Yes — that is the designed use. NEC 501.10(B)(4) says Division 2 boxes and fittings need not be explosionproof unless they contain arcing, sparking, or high-temperature devices, and the manufacturer selectors designate the gasketed families — Form 7, Form 8, Mark 9, and moguls — for exactly that service in threaded metal systems. Form 5 does not appear in those selectors; treat it as unclassified-area gear.

What do I use in Class I, Division 1?

Explosionproof only. Division 1 bodies and junction boxes must be suitable for Division 1 and threaded for rigid or IMC — the explosionproof condulet families (GUA/GUB/EAB/EAJ-style, with threaded covers). No general-purpose form qualifies, and between a sealing fitting and an explosionproof enclosure the L, T, and X shapes may be no larger than the conduit trade size per 501.15(A)(1). See the hazardous location wiring chart for the seal locations themselves.

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