Dear Mr. Electrician: What are the five inch electrical conduit dimensions?
Answer: Five Inch (5″) is the trade size, not the actual dimension of the electrical conduit. One hundred twenty-nine (129) is the metric designator, not the exact dimension in millimeters.
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The dimensions for various types of five-inch electrical conduits are below. The information was derived from several sources and should not be considered precise. Dimensions may vary slightly between manufacturers.
Use a 5 1/2″ (140mm) hole saw for five-inch conduit fittings.
Table of Contents:
- Rigid Conduit
- PVC 40 Conduit
- PVC 80 Conduit
- Fiberglass Conduit
- HDPE Conduit
- More Conduit Dimensions
- Conduit Links
Click here for my post with more detailed descriptions of various types of electrical conduits and their National Electrical Code references without dimensions.
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 5″ RMC weighs approximately 1400 pounds or 634.9 kilograms.
Five-inch RMC has an inside diameter of 5.073″ or 128.85mm. It has an outside diameter of 5.563″ or 141.30mm. The wall thickness is .245″ or 6.20mm. 5″ rigid conduit requires a 5 1/2″ hole for the conduit and fittings. A tap needs a 5 9/32″ (5.2813″) hole for taper pipe threads.
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. Five-inch PVC 40 has some flexibility with an inside diameter of 5.047″ or 128.1938mm.
It has an outside diameter of 5.563″ or 141.3002mm. The wall thickness is .258″ or 6.5532mm. 5″ Schedule 40 weighs 315 pounds per 100 feet (142.88148 kilograms). 5″ PVC requires a 5 1/2″ hole for the conduit fittings. A tap needs a 5 9/32″ (5.2813″) hole. Threads per inch for the fittings is 8 NPT.
5″ Rigid Polyvinyl Chloride Conduit (PVC) schedule 80 is a nonmetallic, non-conductive electrical conduit that is good to use indoors and outdoors or underground. It has limited flexibility. Five Inch Schedule 80 PVC has an inside diameter of 4.813″ or 122.2502mm.
Schedule 80 has an outside diameter of 5.563″ or 141.3002mm. The wall thickness is .375″ or 9.525mm. 5″ Schedule 80 weighs 428 pounds per 100 feet or 194.137376 kilograms. 5″ PVC requires a 5 1/2″ hole for the conduit fittings. A tap needs a 5 9/32″ (5.2813″) hole. Threads per inch for the fittings is 8 NPT.
5″ Reinforced Thermosetting Resin Conduit (RTRC or Fiberglass) is a nonmetallic conduit that is suitable for many conditions. Five-inch RTRC Fiberglass has an inside diameter of 5.380″ or 136.652mm.
The outside diameter is 5.572″ or 141.5288mm. The conduit wall thickness is .096″ or 2.4384mm. 100 feet of five-inch MW RTRC weighs 120 pounds or 54.43104 kilograms. It requires a 5 1/2″ hole for the conduit fittings. A tap needs a 5 9/32″ (5.2813″) hole. Threads per inch for the fittings is 8 NPT.
5″ High-Density Polyethylene (HDPE) is a non-metallic flexible conduit available in long reel lengths to reduce joints and installation time.
Five-inch HDPE has an outside diameter of 5.563″ or 141.3002mm. Type SDR-9 has an inside diameter of 4.253″ or 108.0262mm. 100 feet of 5″ HDPE weighs 416 pounds or 188.694272 kilograms. The wall thickness is .618″ or 15.6972mm.
All five-inch conduit and fittings require a five-and-a-half inch (5 1/2″ or 140mm) opening into an electrical box. The hole can be made with a hole saw.
A tap for five-inch electrical conduit or fittings requires a 5 9/32″ (5.2813″) hole for taper pipe threads. 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.
Click Here for my blog post with hole saw sizes for electrical conduit.
OTHER SIZE ELECTRICAL CONDUIT DIMENSIONS
1 1/4″ (35) 1 1/2″ (41) 2″ (53)
2 1/2″ (63) 3″ (78) 3 1/2″ (91)
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.
LINKS TO 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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