Irby Circuit

By David R. Burnette, Wheatland Tube Company

Steel Rigid and EMT has been a “mature product” for as long as anyone can remember. The first rigid conduit system was probably the system installed by Greenfield in 1888; zinc tubes with copper elbows were used. Once people recognized the merits of electrical raceway systems, conduits were offered and installed made of insulating paper tubes, woven fabrics, fiber and even “flexible glass” as the insulating and sheathing material. Eventually paper tubes encased in steel armor or thin sheet brass were offered to provide greater physical protection. By 1890, wires were being installed in plain unlined gas pipe as the simplicity and low cost, combined with the added strength, made this a preferred wiring method. The next twenty-five years saw further developments in steel rigid conduit with hot-dipped galvanized rigid product finally being available around 1912.

As early as December of 1928, “Electrical World” mentioned a reduced wall raceway, “Electrical Metallic Tubing”, which was approved by the National Electric Code in limited applications.

It appears that during this period of product development, rigid and EMT was always sold with a maximum length of ten feet.

With the recent harmonization of the North American codes and standards, the restrictive language limiting the conduit length to ten feet was removed. This opened up the possibilities for the conduit producers to offer longer lengths. 20 Foot EMT is now available in all Trade Sizes (1/2 - 4) and 20 Foot Hot Dipped Rigid Steel Conduit is available in Trade Sizes 2-6.

Twenty Foot EMT and Rigid Steel Conduit offers immediate and obvious labor savings for the electrical contractor without requiring an investment in equipment, training or time. Every electrical installation offers different challenges. While not suitable for every job, 20 Foot EMT and Rigid may be a simple way to reduce installation costs. One of the first jobs that used 20 Foot Rigid was a prison in Upstate New York. Twenty foot lengths of 4 inch Steel Rigid, direct buried on a gravel bed, were used to connect all the manhole access points. The DFW Airport People-Mover has 6 inch Rigid installed as high as 30 feet off the ground. Both jobs were perfect installations for 20 Foot Rigid. Some recent 20 Foot EMT jobs have included off-site Data Centers, Distribution Centers, Hospitals, and Shopping Centers. Some contractors that pre-fabricate stub-ups etc. have standardized on 20 Foot EMT to reduce waste.

Extra feet equals extra savings.

The response to 20 Foot EMT and Rigid Steel conduit has been overwhelmingly positive:

  • “This is one of the best time-saving items a manufacturer has come up with in a long time.”
  • “The men that installed the 20 Foot EMT were very proud of their work due to the straight runs and how good it looks.”
  • “We’ll continue to use 20 foot product on future jobs.”

It’s simple. More really is less!

According to contractors, the advantages of using 20-Foot EMT are obvious:

  • fewer couplings to purchase and install
  • less waste in prefab work
  • less taping of set screw couplings in long runs
  • easier installation of vertical runs
  • conduit runs that are cleaner and straighter — a better looking installation

See the Savings!

Wheatland Tube Company has developed a 20 Foot EMT Savings Calculator tool to help the designer or installer determine the possible savings of using 20 Foot EMT. This calculation engine has been developed by Wheatland Tube, with the cooperation, leadership and expertise of electrical engineers and installers. Find out how much you can save using Wheatland Tube Company’s 20-Foot EMT. The 20-Foot EMT Savings Meter will actually show you the possible savings.

Visit the Wheatland Tube Company website at www.wheatland.com and click on the EMT Calculator to access the on-line version or contact your local Irby branch to see how 20 Foot EMT can improve the profitability of your next project. You only need to enter information such as EMT size, length of runs, number of runs, type of connector, labor rate, labor and supervisory costs and sales tax rate.