Columns are defined by several standards (height, shed profil, glaze, minimum paste composition, fittings, fasteners).
One of the main standardization bodies for insulating columns is the IEC: International Electrotechnical Commission.
Today, we’ve prepared an explanatory diagram to help you understand why the C4-450 d column is described in this way.
It’s related to IEC 60273.
We apply other standards such as ANSI for North America.