Answer: The dimensions for various types of 2.5″ electrical conduits are below. Two and One Half Inch (2.5″) is the trade size, not the actual dimension of electrical conduit. Sixty three (63) is the metric designator not the actual dimension in millimeters.
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The information was derived from several sources and should not be considered precise. Dimensions may vary slightly between manufacturers.
Use a 3″ (76mm) hole saw for two-and-a-half-inch conduit fittings.
Table of Contents:
- Rigid Metal Conduit
- Intermediate Metal Conduit
- Flexible Metal Conduit
- PVC 40
- PVC 80
- Other Conduit Sizes
See my conduit description article for details on various types of electrical conduits and their National Electrical Code references.
METAL ELECTRICAL CONDUIT
2.5″ Electrical Metallic Tubing (EMT or Thinwall) is a smooth, lightweight galvanized metal conduit with an inside diameter of 2.731″ or 69.4mm. The outside diameter is 2.875″ or 73mm. The wall thickness of 2.5″ EMT is .072″ or 1.83mm.
100 feet of 2.5″ EMT weighs approximately 216 pounds or 98 kilograms. It requires a 3″ hole for the conduit fittings. A tap needs a 2 5/8″ hole. Threads per inch for the fittings is 8 NPT.
2.5″ Rigid Metal Conduit (RMC) is a heavy-weight conduit with a galvanized finish throughout. It has factory threads with a 3/4″ per foot taper, 8 threads per inch NPT. 100′ of 2.5″ RMC weighs approximately 559 pounds or 253.5 kilograms. Usually, one threaded coupling is furnished with each length of RMC.
Two-and-a-half-inch RMC has an inside diameter of 2.469″ or 62.71mm. It has an outside diameter of 2.875″ or 73mm. The wall thickness is .193″ or 4.90mm. 2.5″ Rigid requires a 3″ hole for the conduit and fittings. A tap needs a 2 5/8″ hole.
2.5″ Intermediate Metal Conduit (IMC) is a lighter-weight version of RMC. It has a galvanized finish inside and out and can be used in many of the same environments as RMC. It has factory threads with a 3/4″ per foot taper and 8 threads per inch NPT. It also utilizes the same couplings and fittings as RMC. Usually, one coupling is furnished with each 10′ length of IMC.
100 feet of 2.5″ IMC weighs approximately 441 pounds or 200 kilograms. 2.5″ IMC has an inside diameter of 2.597″ or 64.9mm. It has an outside diameter of 2.857″ or 72.6mm. The wall thickness is .15″ or 3.81mm.
2.5″ Flexible Metal Conduit (FMC or Greenfield) is a galvanized finished flexible metal electrical conduit composed of a continuously formed interlocking metal strip. 100 feet of 2.5″ Reduced Wall Steel Greenfield weighs approximately 150 pounds (68.0388 kilograms). Reduced Wall 2.5″ Aluminum FMC weighs 66 pounds or 29.937072 kilograms.
2.5″ FMC has a minimum inside diameter of 2.500″ or 63.5mm. It has a minimum outside diameter of 2.860″ or 72.644mm and a maximum outside diameter of 3.060″ or 77.724mm. The minimum bending radius is 15 inches or 381mm. 2.5″ Flex requires a 3″ hole for the conduit fittings. A tap needs a 2 5/8″ hole. Threads per inch for the fittings is 8 NPT.
100 feet of 2.5″ Sealtight weighs 183 pounds or 83.01 kilograms. It has an inside minimum diameter of 2.480″ or 62.992mm and a maximum inside diameter of 2.505″ or 63.627mm. It has a minimum outside diameter of 2.840″ or 72.136mm and a maximum outside diameter of 2.875″ or 73.025mm. The minimum bending radius is 15 inches (381mm). Fittings require a 3″ hole. A tap needs a 2 5/8″ hole. Threads per inch for the fittings is 8 NPT.
NON-METALLIC ELECTRICAL CONDUIT
2.5″ Rigid Polyvinyl Chloride Conduit (PVC) schedule 40 is a nonmetallic, non-conductive electrical conduit that is good to use indoors and outdoors or underground. It has some flexibility with an inside diameter of 2.469″ or 62.7126mm.
Two-and-a-half-inch PVC 40 has an outside diameter of 2.875″ or 73.025mm. The wall thickness is .203″ or 5.1562mm. 2.5″ Schedule 40 weighs 124 pounds per 100 feet (56.245408 kilograms). 2.5″ PVC requires a 3″ hole for the conduit fittings. A tap needs a 2 5/8″ hole. Threads per inch for the fittings is 8 NPT.
Schedule 80 has an inside diameter of 2.323″ or 59.0042mm. It has an outside diameter of 2.875″ or 73.025mm. The wall thickness is .276″ or 7.0104mm. 2.5″ Schedule 80 weighs 154 pounds per 100 feet or 69.853168 kilograms. 2.5″ PVC requires a 3″ hole for the conduit fittings. A tap needs a 2 5/8 ” hole. Threads per inch for the fittings is 8 NPT.
2.5″ Reinforced Thermosetting Resin Conduit (RTRC or Fiberglass) is a nonmetallic conduit that is suitable for many conditions. It has an inside diameter of 2.735″ or 69.469mm. The outside diameter is 2.875″ or 73.025mm. The conduit wall thickness is .070″ or 1.778mm.
100 feet of two-and-one-half-inch SW RTRC weighs 46 pounds or 20.865232 kilograms. It requires a 3″ hole for the conduit fittings. A tap needs a 2 5/8″ hole. Threads per inch for the fittings is 8 NPT.
Two-and-a-half-inch HDPE Type SDR-9 has an inside diameter of 2.199″ or 55.8546mm. 100 feet of 2.5″ HDPE weighs 111 pounds or 50.348712 kilograms. The wall thickness is .319″ or 8.1026mm.
All two and a half inch 2.5″ (63) conduit and fittings require a 3 inch 3″ opening into an electrical box. The hole can be made with a hole saw or a knockout punch.
A tap for two-and-one-half-inch (2.5″) (63) conduit or conduit fittings requires a 2 5/8″ hole. The threads per inch is 8 National Pipe Thread (NPT).
The standard length for most conduits is ten feet (10′) or 3.048 meters. Twenty-foot (20′) (6.096 meters) lengths of metal conduit are available but not always in stock. PVC conduit is available in ten-foot (10′) and some sizes, twenty-foot (20′) lengths. RTRC mostly comes in twenty-foot (20′) lengths. The flexible conduits come in various length coils and reels depending on the trade size. Some electrical supply companies will cut the flexible conduits to length.
See my hole saw chart for each size of electrical conduit.
MORE ELECTRICAL CONDUIT DIMENSIONS
For more conduit code details and conduit fill see Chapter 9, Tables 1, 4, 5, and 5A.
See the tables in Informative Annex C at the back of the National Electrical Code (NFPA 70) for the allowable number of wires in each size conduit.
ELECTRICAL CONDUIT MANUFACTURERS
Aluminum and Steel Conduit Products – https://www.westerntube.com/
Fiberglass Conduit Products – https://championfiberglass.com/
PVC Conduit products – https://www.cantexinc.com/
Steel Conduit Products – https://www.alliedeg.us/
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