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Electrical Metal Tubing (EMT) - Conduits

Trade sizes and max. distance between conduit supports.

Electrical Metallic Tubing (EMT) - Thinwall Conduit

Electrical Metallic Tubing (EMT) is unthreaded with circular cross section dimensions:

Electrical Metal Tubing (EMT) - Conduits
Conduit Trade SizeOutside DiameterInside DiameterMax Distance Between Supports
Rigid Metal (PVC)
(in)(mm)(in)(mm)(in)(mm)(ft)(m)
1/2 16 0.706 17.9 0.622 15.8 10 3
3/4 21 0.922 23.4 0.824 20.9 10 3
1 27 1.163 29.5 1.05 26.6 12 3
1 1/4 35 1.510 38.4 1.38 35.1 14 5
1 1/2 41 1.740 44.2 1.61 40.9 14 5
2 53 2.197 55.8 2.07 52.5 16 5
2 1/2 63 2.875 73.0 2.73 69.3 16 6
3 78 3.500 88.9 3.36 85.2 20 6
3 1/2 91 4.000 101.6 3.83 97.4 20 7
4 103 4.500 114.3 4.33 110 20 7
  • 1 inch = 25.4 mm
  • 1 ft (foot) = 0.3048 m

The outside tube is galvanized for corrosion protection and the inside has corrosion-resistant coating.

According to National Electric Code (US NEC or NFPA 70) Article 344 for Rigid Metal Conduit and Article 358 Electrical Metallic Tubing.

  • a conduit must be supported at intervals no longer than 3 m (10 ft) and fastened not more than 0.9 m (3 ft) from a box, fitting, etc.
  • the distance between supports for straight runs of conduit shall be permitted in accordance to the table above provided the conduit is made up with threaded couplings and such supports prevent transmission of stresses to termination where conduit is deflected between supports
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