Heating Element Design Basics Nichrome A (80), Nichrome C (60)

Ohm’ Law Formulas:

  • Volts = Amperes X Ohms
  • Amperes = Volts/Ohms
  • Ohms = Volts/Amperes
  • Watts = Volts X Amperes
  • Watts = (Volts X Volts) / Ohms
  • Watts = Amperes X Amperes X Ohms
  • Ohms = Watts / (Amperes X Amperes)

Note the amperage values in the Current/Temperature Table in the “Nichrome and Resistance wires” menu item above.  As a general rule you can expect that the amperage value for a *coiled* wire is roughly 30-60% less than the capacity of a *straight* wire as referred to in the table.  For *coiled* wire elements see “Nichrome Wire Tech Tips” PDF file. (accessible in scroll down menu above in “Nichrome and Resistance Wires.”)

Using Ohm’s Law above, & tables (see the Increased Resistance Table), you can calculate the watts at your intended voltage (115 being most common).

See the Wattage/Amperage/Hot Ohms Table. Note that it is based on 115 V.

Taking into account the available space, you can select a wire size that will provide the required wattage. From the amount of total Hot Ohms of your element design, you can use Ohms/Ft Table to estimate the amount of feet you will need of a given size.

General Design Tips

Use this information as a guide only. The finished element should be thoroughly tested to verify that the rise in resistance with temperature has been properly accounted for.

If additional technical info on designing heating elements is desired, please request more design info from our sales dept at sales@wiretron.com

Terminate elements by brazing, welding, or spot welding if possible. Pressure joints may be used but there is a possibility of poor contact due to yielding of the clamping device. In such a case, two nuts used to clamp the element are better than one alone.

Allow room in your design for expansion and contraction of the element.