Dear Mr. Electrician: What are the dimensions of six inch electrical conduit?
Answer: Six Inch (6″) is the trade size, not the actual dimension of the electrical conduit. One hundred fifty-five (155) is the metric designator, not the exact dimension in millimeters.
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The actual dimensions for various types of 6″ electrical conduit are below. The information was derived from several sources and should not be considered precise. Dimensions may vary slightly between manufacturers.
Table of Contents:
- Rigid Conduit
- PVC 40 Conduit
- PVC 80 Conduit
- Fiberglass Conduit
- HDPE Conduit
- More Conduit Dimensions
- Conduit Links
Use a 6 5/8″ (168mm) hole saw for six inch conduit fittings.
Click here for my article with more detailed descriptions of various types of electrical conduit and their code references without dimensions.
6″ 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, eight threads per inch NPT. 100′ of 6″ RMC weighs approximately 1840 pounds or 834.60928 kilograms.
Six inch RMC has an inside diameter of 6.093″ or 154.76mm. It has an outside diameter of 6.625″ or 168.28mm. The wall thickness is .266″ or 6.80mm. 6″ Rigid requires a 6 5/8″ hole for the conduit and fittings.
6″ Rigid Polyvinyl Chloride Conduit (PVC) schedule 40 is a nonmetallic, non-conductive electrical conduit approved for use indoors and outdoors or underground.
Six inch PVC 40 has an inside diameter of 6.065″ or 154.05mm. It has some flexibility and an outside diameter of 6.625″ or 168.28mm. The wall thickness is .280″ or 7.112mm. 6″ Schedule 40 weighs 409 pounds per 100 feet (185.519128 kilograms). 6″ PVC requires a 6 5/8″ hole for the conduit fittings. Threads per inch for the fittings is 8 NPT.
6″ Rigid Polyvinyl Chloride Conduit (PVC) schedule 80 is a nonmetallic, non-conductive electrical conduit that is good to use indoors and outdoors or underground. Six-inch PVC 80 has limited flexibility with an inside diameter of 5.761″ or 146.33mm.
Schedule 80 has an outside diameter of 6.625″ or 168.28mm. The wall thickness is .432″ or 10.9728mm. 6″ Schedule 80 weighs 588 pounds per 100 feet or 266.712096 kilograms. 6″ PVC requires a 6 5/8″ hole for the conduit fittings. Threads per inch for the fittings is 8 NPT.
6″ Reinforced Thermosetting Resin Conduit (RTRC or Fiberglass) is a nonmetallic conduit that is suitable for many conditions. Six-inch RTRC Fiberglass Conduit has an inside diameter of 6.435″ or 163.449mm.
The outside diameter is 6.627″ or 168.3258mm. The conduit wall thickness is .096″ or 2.4384mm. 100 feet of six-inch MW RTRC weighs 142 pounds or 64.41 kilograms. It requires a 6 5/8″ hole for the conduit fittings. Threads per inch for the fittings is 8 NPT.
6″ High-Density Polyethylene (HDPE) is a non-metallic flexible conduit available in long reel lengths to reduce joints and installation time.
Six-inch HDPE has an outside diameter of 6.625″ or 168.275mm. Type SDR-9 has an inside diameter of 5.065″ or 128.651mm. 100 feet of 6″ HDPE weighs 590 pounds or 267.61928 kilograms. The wall thickness is .736″ or 18.6944mm.
All six inch 6″ (155) conduit and fittings require a six-inch and five-eighths (6 5/8″) opening into an electrical box. The hole can be made with a hole saw.
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 to see my article with hole saw sizes for all electrical conduits.
See my article describing various electrical conduit types.
OTHER 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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