Inch and One Half Electrical Conduit Dimensions

Dimensions of 1 1/2" Electrical Conduit Used in North America

Dear Mr. Electrician:  What are inch and one-half electrical conduit dimensions?

Answer:  Inch and one-half electrical conduit dimensions differ from the trade size.  Inch and One Half (1 1/2″) is the trade size, not the actual dimension of the electrical conduit.  Forty-one (41) is the metric designator, not the exact dimension in millimeters.

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The dimensions for various types of 1 1/2″ electrical conduits are below.  The information was derived from several sources and should not be considered precise. Sizes may vary slightly between manufacturers.

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Use a two-inch (2″ )or (51mm) hole saw for 1 1/2″ conduit fittings.  You can see all hole saw sizes for conduits on my blog post here.

METAL ELECTRICAL CONDUIT

1 1/2″ Electrical Metallic Tubing (EMT or Thinwall) is a smooth, lightweight galvanized metal conduit with an inside diameter of 1.610″ or 40.89mm.  The outside diameter is 1.740″ or 44.2mm.  The wall thickness of 1 1/2″ EMT is .065″ or 1.65mm.

100 feet of 1 1/2″ EMT weighs approximately 116 pounds or 52.6 kilograms.  The conduit fittings require a 2″  hole. A tap needs a 1 3/4″ hole.  Threads per inch for the fittings is 11.5 NPT.

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1 1/2″ Rigid Metal Conduit (RMC or Rigid) is a heavy-weight conduit with a galvanized finish throughout.  It has factory threads with a 3/4″ per foot taper,  11.5 threads per inch NPT.

100′ of inch-and-a-half RMC weighs approximately 263 pounds or 119.3 kilograms.  It has an inside diameter of 1.610″ or 40.89mm.  It has an outside diameter of 1.900″ or 48.3mm.  The wall thickness is .138″ or 3.50mm.  1 1/2″ Rigid requires a 2″ hole for the conduit and fittings.  A tap needs a 1 3/4″ hole.

1 1/2″ 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 11.5 threads per inch NPT.  It also utilizes the same couplings and fittings as RMC.

100 feet of 1 1/2″ IMC weighs approximately 194 pounds or 88 kilograms.  1 1/2″ IMC has an inside diameter of 1.703″ or 42.7mm.  It has an outside diameter of 1.883″ or 47.8mm.  The wall thickness is .1″ or 2.54mm.

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1 1/2″ Flexible Metal Conduit (FMC or Greenfield, Flex) is a galvanized finished flexible metal electrical conduit composed of a continuously formed interlocking metal strip.

100 feet of 1 1/2″ Reduced Wall Steel Greenfield weighs approximately 78 pounds  (35.38 kilograms).  Reduced Wall 1 1/2″ Aluminum FMC weighs 31 pounds or 14.06  kilograms.

1 1/2″ FMC has a minimum inside diameter of 1.500″ or 38.1mm and a maximum inside diameter of 1.575″ or 40.005mm.  It has a minimum outside diameter of 1.850″ or 46.99mm and a maximum outside diameter of 1.950″ or 49.53mm.  The minimum bending radius is 10 inches or 254mm.  1 1/2″ Flex requires a 2″ hole for the conduit fittings.  A tap needs a 1 3/4″ hole.  Threads per inch for the fittings is 11.5 NPT.

1 1/2″ Liquidtight Flexible Metal Conduit (LFMC or Sealtight) is a flexible metal conduit with a non-metallic, non-conductive outer jacket that makes it suitable for use in wet locations.

100 feet of 1 1/2″ Sealtight weighs 98 pounds or 44.45 kilograms.  It has an inside minimum diameter of 1.575″ or 40.005mm and a maximum inside diameter of 1.600″ or 40.64mm.  It has a minimum outside diameter of 1.865″ or 47.37mm and a maximum outside diameter of 1.900″ or 48.26mm.

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NON-METALLIC ELECTRICAL CONDUIT

1 1/2″ Rigid Polyvinyl Chloride Conduit (PVC) schedule 40 is a non-metallic, non-conductive electrical conduit that is good to use indoors, outdoors, or underground.  It has some flexibility with an inside diameter of 1.610″ or 40.89mm.  It has an outside diameter of 1.900″ or 48.26mm.  The wall thickness is .145″ or 3.683mm.

1 1/2″ Schedule 40 weighs 55 pounds per 100 feet (24.94756 kilograms).  1 1/2″ PVC requires a 2″ hole for the conduit fittings.  A tap needs a 1 3/4″ hole.  Threads per inch for the fittings is 11.5 NPT.


1 1/2″ (41) Rigid Polyvinyl Chloride Conduit (PVC) schedule 80 is a non-metallic, non-conductive electrical conduit that is good to use indoors and outdoors or underground.  It has limited flexibility.

Schedule 80 has an inside diameter of 1.50″ or 38.10mm.  It has an outside diameter of 1.900″ or 48.26mm.  The wall thickness is .200″ or 5.08mm.  1 1/2″ Schedule 80 weighs 72 pounds per 100 feet and 32.66 kilograms.  1 1/2″ PVC requires a 2″ hole for the conduit fittings.  A tap needs a 1 3/4″ hole.  Threads per inch for the fittings is 11.5 NPT.

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1 1/2″ Electrical Non-metallic Tubing (ENT or Smurf) is a non-metallic, non-conductive flexible conduit with an inside diameter of 1.554″ or mm.  It weighs 39 pounds per 100 feet or 17.69 kilograms.

1 1/2″ ENT has an outside diameter of 1.90″ or 48.26mm.  The minimum bend radius is 8.25 inches.  1 1/2″ fittings require a 2″ hole.  A tap needs a 1 3/4″ hole.  Threads per inch for the fittings is 11.5 NPT.

The minimum bending radius is 10 inches (254mm).  Fittings require a 2″ hole.  A tap needs a 1 3/4″ hole.  Threads per inch for the fittings is 11.5 NPT.

1 1/2″ Liquidtight Flexible Non-metallic Conduit (LFNC or CarFlex) is a non-metallic conduit suitable for wet conditions.  100′ of 1 1/2″ Carflex weighs 48 pounds.  It has an inside minimum diameter of 1.575″ or 40.005mm and a maximum inside diameter of 1.600″ or 40.64mm.

Inch and a-half LFNC have a minimum outside diameter of 1.865″ or 47.37mm and a maximum outside diameter of 1.900″ or 48.26mm.  The minimum bending radius is 9 inches or 228.6mm.  The conduit fittings require a 2″ hole.  A tap needs a 1 3/4″ hole.  Threads per inch for the fittings is 11.5  NPT.

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1 1/2″ Reinforced Thermosetting Resin Conduit (RTRC or Fiberglass) is a non-metallic conduit suitable for many conditions.  It has an inside diameter of 1.760″ or 44.704mm.  The outside diameter is 1.900″ or 48.26mm.  The conduit wall thickness is .070″ or 1.778mm.

One hundred feet of one-and-a-half-inch SW RTRC weighs 33 pounds and 14.968536 kilograms.  The conduit fittings require a 2″ hole.  A tap needs a 1 3/4″ hole.  Threads per inch for the fittings is 11.5 NPT.

1 1/2″ High-Density Polyethylene (HDPE) is a non-metallic flexible conduit in long reel lengths to reduce joints and installation time.  It has an outside diameter of 1.900″ or 48.26mm.  Type SDR-9 has an inside diameter of 1.453″ or 36.9062mm.

100 feet of 1 1/2″ HDPE weighs 48.5 pounds or 21.999212 kilograms.  The wall thickness is .211″ or 5.3594mm.

All one-and-a-half inch (1.5″) (41mm) conduit and fittings require a two inch 2″ opening into an electrical box.  The hole can be made with a hole saw or a knockout punch.

A tap for one-and-a-half inch (1.5″) (41mm) conduit or conduit fittings requires a 1 3/4″ hole.  The threads per inch are 11.5 National Pipe Thread (NPT).

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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 coils and reels of various lengths depending on the trade size.  Some electrical supply companies will cut the flexible conduits to length.

See my post describing various electrical conduit types.

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Emergency disconnect, service disconnect sticker label as required by article 230.85 in the National Electrical Code. CLICK THE IMAGE for more Emergency Disconnect Stickers at Redbubble.
Emergency Disconnect, Service Disconnect sticker label as required by article 230.85 in the National Electrical Code. CLICK THE IMAGE for more Emergency Disconnect Stickers at Redbubble.

OTHER ELECTRICAL CONDUIT DIMENSIONS

1/2″ (16)       3/4″ (21)       1″ (27)

1 1/4″ (35)       2″ (53)       2 1/2″ (63)

3″ (78)       3 1/2″ (91)       4″ (103)

5″ (129)        6″ (155)

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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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