Half Inch 1/2″ (16mm) Electrical Conduit Dimensions

Half Inch 1/2″ is the trade size, not the actual dimension of electrical conduit.  Sixteen 16 is the metric designator not the actual dimension in millimeters.  The dimensions for various types of 1/2″ electrical conduit are below.  The information was derived from several sources and should not be considered precise.  Dimensions may vary slightly between manufacturers.

1/2″ (16) Electrical Metallic Tubing (EMT or Thinwall) is a smooth light weight galvanized metal conduit that has an inside diameter of 0.622″ or 15.7988mm.  It has an outside diameter of 0.706″ or 17.9324mm.  100 feet of 1/2″ EMT weighs 30 pounds or 13.6 kilograms.  The wall thickness of 1/2″ EMT is 0.042″ or 1.0668mm.  The fitting and conduit opening is 7/8″.  The tap drill is 23/32″.

1/2″ (16) 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.  100′ of RMC weighs approximately 82 pounds or 37.2 kilograms.  It has an inside diameter of 0.662″ or 16.8148mm.  It has an outside diameter of 0.840″ or 21.336mm.  The wall thickness is .104″ or 2.60mm.  The fitting and conduit opening is 7/8″.  The tap drill is 23/32″.

1/2″ (16) 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.  1/2″ IMC weighs 62 pounds per 100 feet or 28.1 kilograms.  IMC has an inside diameter of 0.660″ or 16.764mm.  It has an outside diameter of 0.815″ or 20.701mm.  The wall thickness is .078″ or 1.97mm.  The fitting and conduit opening is 7/8″.  The tap drill is 23/32″.

1/2″ (16) Flexible Metal Conduit (FMC or Greenfield) is a galvanized finished flexible metal electrical conduit composed of a continuously formed interlocking metal strip.  100′ of reduced wall steel flexible metal conduit weighs 27 pounds or 12.246984 kilograms.  100′ of aluminum weighs 9 pounds and 4.082328 kilograms.  FMC has a minimum inside diameter of 0.625″ or 15.875mm and a maximum inside diameter of 0.645″ or 16.383mm.  It has a minimum outside diameter of 0.860″ or 21.844mm and a maximum outside diameter of 0.920″ or 23.368mm.  The minimum bending radius is 4 inches or 101.6mm.  The fitting and conduit opening is 7/8″.  The tap drill is 23/32″.

1/2″ (16) 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 0.622″ or 15.7988mm.  It can also be heated and bent.  It has an outside diameter of 0.840″ or 21.336mm.  The wall thickness is .109″ or 2.7686mm.  100′ weighs 17 pounds or 7.711064 kilograms.  This is available in 10′ (3.048 meters) and 20′ (6.096 meters) lengths.  The fitting and conduit opening is 7/8″.  The tap drill is 23/32″.

1/2″ (16) 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, but can be heated and bent to any angle.  It weighs 21 pounds (9.525432 kilograms) per 100 feet.  Schedule 80 has an inside diameter of 0.546″ or 13.8684mm.  It has an outside diameter of 0.840″ or 21.336mm.  The wall thickness is .147″ or 3.7338mm.  The fitting and conduit opening is 7/8″.  The tap drill is 23/32″.

1/2″ (16) Electrical Nonmetallic Tubing (ENT or Smurf) is a nonmetallic, non-conductive flexible conduit with an inside diameter of .560″ or 14.224mm.  It has an outside diameter of .840″ or 21.336mm.  100 feet of 1/2″ ENT weighs 10 pounds or 4.53592 kilograms.  The minimum bend radius is 6 inches.  The fitting and conduit opening is 7/8″.  The tap drill is 23/32″.

1/2″ (16) Liguidtight 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.  It has an inside minimum diameter of .622″ or 15.7988mm and a maximum inside diameter of .642″ or 16.3068mm.   It has a minimum outside diameter of .820″ or 20.828mm and a maximum outside diameter of .840″ or 21.336mm.  The minimum bending radius is 4 inches.  The fitting and conduit opening is 7/8″.  The tap drill is 23/32″.

1/2″ (16) Liguidtight Flexible Nonmetallic Conduit (LFNC or CarFlex) is a nonmetallic conduit that is suitable for wet conditions.  It has an inside minimum diameter of .622″ or 15.7988mm and a maximum inside diameter of .642″ or 16.3068mm.  It has a minimum outside diameter of .820″ or 20.828mm and a maximum outside diameter of .840″ or 21.336mm.  100 feet weighs 13 pounds or 5.896696 kilograms.  The minimum bending radius is 4 inches.  The fitting and conduit opening is 7/8″.  The tap drill is 23/32″.

1/2″ (16) Reinforced Thermosetting Resin Conduit (RTRC or Fiberglass) is a nonmetallic rigid conduit that is suitable for many conditions.   Unfortunately 1/2″ RTRC does not seem to be available.  The next size up is 3/4″.

1/2″ (16) High Density Polyethylene (HDPE) is a non-metallic flexible conduit available in long reel lengths to reduce joints and installation time.  It has an outside diameter of .840″ or 21.336mm.  Type SDR-9 has an inside diameter of .634″ or 16.1036mm.  100 feet of 1/2″ HDPE weighs 10 pounds or 4.53592 kilograms.  The wall thickness is .093″ or 2.3622mm.

All half inch 1/2″ (16) conduit and fittings require a 7/8″ opening into an electrical box.  The hole can be made with a hole saw or a knockout punch.

A tap for 1/2″ (16) conduit or conduit fittings requires a 23/32″ hole. The threads per inch is fourteen 14 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 in 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 flexible conduit to length.

See my post describing various electrical conduit types.

Other size electrical conduits: 3/4″ (21)

1″ (27)       1 1/4″ (35)       1 1/2″ (41)

2″ (53)         2 1/2″ (63)          3″ (78)

3 1/2″ (91)        4″ (103)        5″ (129)

6″ (155)

For more conduit code details and conduit fill see Chapter 9, Tables 1, 4, 5 and 5A.
See the tables in Informative Annex C in the back of the “National Electrical Code” for the allowable number of wires in each size conduit.