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newSchoolWorks.com › VoTechWorks › Manufacturing & Marine › Industrial Maintenance › Industrial Electrical Systems for Manufacturing and Marine Maintenance › Lesson 8
MFG-INDU16-05 · Lesson 8 · 16.5 clock hours · lab

Conduit Installation: Rigid Metal Conduit, EMT, and Flexible Conduit

Objective. The learner will cut, ream, bend, and install a three-piece conduit run consisting of EMT with at least two 90-degree bends and one offset, secured with proper supports, and pulled with conductors sized per NEC fill tables, meeting a plumb and level standard of within 1/4 inch over 4 feet.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed engineer or certified journey-level tradesperson or by a certification or approval body. It is a study draft and may contain errors. Do not use it as instructions for work on a job site or on live equipment. Always follow your instructor, your supervising professional, and current official references and regulations.

VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.

Conduit Installation: Rigid Metal Conduit, EMT, and Flexible Conduit

Why Conduit Matters

Conduit is the mechanical protection system for electrical conductors. In manufacturing plants and marine facilities, wiring runs through areas with heavy vibration, moisture, chemicals, and physical impact. Choosing the right conduit type and installing it correctly keeps conductors safe, meets the National Electrical Code (NEC), and protects workers from shock and fire hazards.

Conduit Types Used in This Lab

Rigid Metal Conduit (RMC) is heavy-wall threaded steel pipe. It offers the strongest physical protection and is listed for use in all environments, including wet and hazardous locations. Cutting and threading RMC requires a pipe threader and reamer. RMC serves as the equipment grounding conductor when fittings are properly torqued.

Electrical Metallic Tubing (EMT) is thin-wall, unthreaded steel tubing. It is lighter and easier to bend than RMC. EMT uses compression or set-screw fittings rather than threads. It is suitable for most indoor and some outdoor dry locations. EMT is the most common conduit in light commercial and manufacturing interior applications and is the primary material practiced in this lab.

Flexible Metal Conduit (FMC) — often called Greenfield — is spiral-wound interlocked steel. It is used for the final connection to motors, compressors, and other vibrating equipment where a rigid run cannot absorb movement. FMC requires separate grounding conductors because the spiral seam does not provide reliable ground continuity in all conditions. Liquidtight flexible metal conduit (LFMC) adds a plastic jacket for wet or oily locations such as marine bilge areas.

Safety Before You Start

Apply lockout/tagout (LOTO) procedures before working on or near any energized panel or circuit — even a training panel. Verify the circuit is de-energized with a meter rated for the voltage present. Wear safety glasses at all times during cutting and bending; metal chips and swarf are a serious eye hazard. Wear leather gloves when handling cut conduit ends; freshly cut steel is razor-sharp until properly reamed and filed. Steel-toed footwear is required in the lab area. Keep the work area clear of tripping hazards, especially conduit lengths on the floor.

Cutting and Reaming EMT

Measure the required length carefully before cutting. Use a tubing cutter for clean square cuts; tighten the cutter wheel gradually and rotate the tool around the tube — forcing the wheel causes deformation. After cutting, use the reamer attached to the cutter or a stand-alone reamer to remove all burrs from the inside edge. Burrs nick conductor insulation during pulling and can cause insulation failures that are invisible after installation. A properly reamed end feels smooth to a gloved finger.

Bending EMT: Key Concepts

A hand bender is a formed shoe matched to a specific conduit size — never use a 1/2-inch bender on 3/4-inch EMT. Each bender is stamped or labeled with the take-up (also called deduction) for a 90-degree stub-up: the distance you subtract from the desired stub height so the finished bend lands at the right measurement. Common take-up values are stamped on the bender handle.

A stub-up is a single 90-degree bend used to rise from the floor or enter a box from below. Mark the conduit at the measurement equal to the desired stub height minus the take-up, place the bender arrow on that mark, and pull the handle to the 90-degree mark.

A back-to-back 90 makes a U-shape or offset section. Make the first bend, measure the desired distance to the second bend, add the gain (the amount of conduit length saved by the arc of the first bend) to your measurement, mark that point, flip the conduit, and make the second bend.

An offset consists of two equal bends in opposite directions to move the conduit around an obstacle or to change elevation by a set amount. Common offset angles are 22.5°, 30°, and 45°. A 30-degree offset has a multiplier of 2.0, meaning the distance between bend marks equals the desired offset height multiplied by 2.0.

Conduit Support Requirements

The NEC requires EMT to be supported within a specified distance of every box, fitting, or enclosure and at intervals along the run. Consult the current NEC article for EMT support intervals. Supports must be fastened securely to the structure — use one-hole straps or two-hole straps on steel framing. A run that is not plumb and level looks unprofessional and may prevent box covers from seating correctly. The standard in this lab is within 1/4 inch over any 4-foot section, verified with a torpedo level.

NEC Conduit Fill

The NEC limits how much of a conduit's cross-sectional area can be occupied by conductors. For three or more conductors, the maximum fill is 40% of the conduit's interior cross-sectional area. This limit prevents overheating and makes pulling and future rewiring practical. Values for conductor cross-sectional area and conduit interior area are found in NEC Chapter 9, Tables 4 and 5. Calculate total conductor area, divide by conduit interior area, multiply by 100, and confirm the result is 40% or below before pulling wire.

Pulling Conductors

Apply wire-pulling lubricant (pulling compound) to conductors before feeding them into the conduit. Lubricant reduces friction dramatically, preventing insulation damage and making the pull possible in longer runs. Never use petroleum-based lubricants on thermoplastic insulation such as THHN — use a listed water-based compound. Feed conductors together and pull steadily; jerking can nick insulation on conduit fittings.

Inspection Checklist

Before calling the instructor for sign-off, verify: all bends within ±2 degrees of the specified angle; run plumb and level within 1/4 inch per 4 feet; supports installed at correct intervals; connectors fully seated and secured; conduit fill calculation recorded and confirmed at 40% or below; and all cut ends properly reamed.

Key terms10

Electrical Metallic Tubing (EMT)Thin-wall unthreaded steel conduit joined with compression or set-screw fittings; lighter and easier to bend than rigid metal conduit and used in most interior manufacturing installations.
Rigid Metal Conduit (RMC)Heavy-wall threaded steel pipe providing maximum mechanical protection; listed for all environments including wet and hazardous locations.
Flexible Metal Conduit (FMC)Spiral-interlocked steel conduit used at final connections to vibrating equipment; requires a separate equipment grounding conductor because the seam does not provide reliable ground continuity in all conditions.
Take-up (deduction)The measurement subtracted from the desired stub height when laying out a 90-degree bend; compensates for the arc of the bend so the finished conduit reaches the correct dimension.
GainThe length of conduit saved by the arc of a completed bend; added to the measured distance between two bends when laying out a back-to-back 90.
Conduit fillThe percentage of a conduit's interior cross-sectional area occupied by conductors; the NEC limits this to 40% for three or more conductors to prevent overheating and allow future rewiring.
ReamingRemoving burrs from the inside edge of a freshly cut conduit end to prevent damage to conductor insulation during pulling.
OffsetTwo equal bends in opposite directions that shift a conduit run to a parallel path, used to route around obstacles or step up or down to a box.
Lockout/Tagout (LOTO)An energy-control procedure that de-energizes equipment and physically prevents re-energization while work is performed; required before any work on or near electrical panels or circuits.
THHNA common thermoplastic-insulated, nylon-jacketed copper conductor rated for use in conduit; conductor cross-sectional areas are tabulated in NEC Chapter 9 for fill calculations.

Worked examples4

1. A 1/2-inch EMT stub-up must finish at 10 inches above the floor. The hand bender is stamped with a take-up of 5 inches for 1/2-inch EMT. At what measurement on the conduit should you place the bender arrow?
  1. Identify the desired finished stub height: 10 inches.
  2. Identify the take-up for 1/2-inch EMT from the bender: 5 inches.
  3. Subtract the take-up from the desired stub height: 10 − 5 = 5 inches.
  4. Place the bender arrow on the mark at 5 inches from the end of the conduit, then bend to 90 degrees.
Answer: Place the bender arrow at 5 inches from the end of the conduit. The finished stub will measure 10 inches.
2. You need a 30-degree offset to raise a conduit run by 3 inches to clear an obstacle. The multiplier for a 30-degree offset is 2.0. How far apart should the two bend marks be on the conduit?
  1. Identify the desired rise (offset height): 3 inches.
  2. Identify the multiplier for a 30-degree offset: 2.0.
  3. Multiply the rise by the multiplier: 3 × 2.0 = 6 inches.
  4. Mark the first bend location, then measure 6 inches along the conduit and mark the second bend location. Make both bends at 30 degrees in opposite directions.
Answer: The two bend marks should be 6 inches apart on the conduit.
3. You are installing three 12 AWG THHN conductors in 1/2-inch EMT. Using NEC Chapter 9 tables, the cross-sectional area of one 12 AWG THHN conductor is 0.0133 sq in, and the interior cross-sectional area of 1/2-inch EMT is 0.304 sq in. What is the conduit fill percentage, and does it meet the NEC 40% maximum for three conductors?
  1. Calculate the total area occupied by the three conductors: 3 × 0.0133 = 0.0399 sq in.
  2. Divide the total conductor area by the conduit interior area: 0.0399 ÷ 0.304 = 0.1312.
  3. Convert to a percentage: 0.1312 × 100 = 13.12%.
  4. Compare to the NEC limit: 13.12% is well below the 40% maximum for three conductors.
Answer: The conduit fill is approximately 13.1%, which meets the NEC 40% maximum. The installation is acceptable.
4. You are installing five 10 AWG THHN conductors in 3/4-inch EMT. Each 10 AWG THHN conductor has a cross-sectional area of 0.0211 sq in, and the interior cross-sectional area of 3/4-inch EMT is 0.533 sq in. Does this installation meet the NEC 40% fill limit for three or more conductors?
  1. Calculate the total area of five conductors: 5 × 0.0211 = 0.1055 sq in.
  2. Divide by the conduit interior area: 0.1055 ÷ 0.533 = 0.1979.
  3. Convert to a percentage: 0.1979 × 100 = 19.79%.
  4. Compare to the NEC limit: 19.79% is below 40%, so the fill is acceptable.
Answer: The conduit fill is approximately 19.8%, which is below the 40% NEC maximum. The installation is acceptable.

The math in this lesson3

Learners compute percent conduit fill from conductor areas against the 40 percent NEC limit.
7.RP.3A-CED.4G-SRT.8
Brush up in the math halls at newSchoolWorks.com:
In class: Conduit bending demonstration and practice: instructor demonstrates stub-up, back-to-back 90-degree, and offset bends on EMT using a hand bender, explaining the take-up deduction and gain for each bend size; learners then make three practice bends each, measuring finished angles with a torpedo level and angle finder. · Full conduit run installation: working in pairs, learners plan a conduit run from a mock panel to a junction box across the training wall, mark the layout, cut EMT to length with a tubing cutter, make the required bends, install straps at code-required intervals, and pull three conductors of the specified size using wire-pulling lubricant. · NEC fill verification: before pulling wire, learners calculate conduit fill percentage using NEC Chapter 9 tables for the conductor size and conduit diameter used and confirm it does not exceed 40% for three conductors; the calculation is recorded in the lab notebook and checked by the instructor.
Materials: EMT conduit (1/2 in. and 3/4 in.), rigid metal conduit sample pieces, flexible conduit, hand benders (1/2 in. and 3/4 in.), tubing cutters, reamer, hacksaw, conduit straps and connectors, wire-pulling lubricant, THHN conductors (assorted gauges), torpedo level, tape measure, NEC codebook, NCCER Electrical module
Check: Instructor evaluates finished conduit run against a checklist: all bends within ±2 degrees of specified angle, run plumb and level within 1/4 inch per 4 feet, supports at correct intervals, correct conduit fill calculation with no more than 40% fill; all items on checklist must be satisfactory to pass.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

NCCER Industrial Maintenance – Electrical Systems
1. Which type of conduit is BEST suited for the final connection to a motor because it can absorb vibration?
NCCER Industrial Maintenance – Electrical Systems
2. A worker is about to cut EMT with a tubing cutter. Before pulling conductors, the FIRST action after cutting should be to:
NCCER Industrial Maintenance – Electrical Systems
3. When making a 90-degree stub-up, the take-up value is used to:
MSSC CPT – Safety and Quality
4. The NEC limits conduit fill to 40% for three or more conductors primarily to:
NCCER Industrial Maintenance – Electrical Systems
5. You need a 45-degree offset to clear a pipe. The rise needed is 4 inches and the multiplier for a 45-degree offset is 1.414. How far apart should the two bend marks be, rounded to the nearest tenth of an inch?
MSSC CPT – Safety
6. Before working on or near an electrical panel during a conduit installation, the MOST important safety procedure is to:
NCCER Industrial Maintenance – Electrical Systems
7. Which conduit type uses threaded fittings and provides the GREATEST mechanical protection?
NCCER Industrial Maintenance – Electrical Systems
8. Three 12 AWG THHN conductors (each 0.0133 sq in) are to be pulled into 1/2-inch EMT with an interior area of 0.304 sq in. Which statement correctly describes the NEC fill compliance?
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