Are there standards for labeling electrical conduit? Not specifically. However, the ANSI A 13.1 pipe marking standard provides the label and text sizes that are appropriate for labeling electrical conduit.
The ANSI Z535 standard defines the colors that should be used for safety related labels. For example, yellow with black printing should be used for cautionary labels and orange with black text for warning labels.
The following table shows the ANSI A13.1 standard for label and text size based on conduit diameter:
Outside Conduit Diameter
Minimum Length Label
Minimum Letter Height
There are no codes that specify the quality of electrical conduit labels. However, conduit labels that don't last might as well not even be there. You've wasted your time.
Typical electrical conduit labels should be resistant to abrasion, moisture, dirt and cleaning fluids. Outdoor electrical conduit labels must be resistant to weather and fading in sunlight. Electrical conduit labels in other locations may need to be resistant to oil, grease, extreme temperatures and other harsh environmental conditions.
Electrical conduit should be labeled with the voltage, an ID number, and the locations that the electrical conduit connects from and to. Labels should be placed at both ends of the conduit, at junction boxes, and any other location where information about the wiring in the conduit might be needed.
Several labels may be used to supply all of the needed information. For example, an orange warning label with the text "480 Volts" might be used. An arrow may be used to indicate the direction of power flow, from the source to the point where the power is distributed or used.
A second label, white in color, may be used to identify the purpose, source and destination of the conduit. The label with the voltage is orange because it is a safety related label informing about the voltage hazard. The second label is white because it is an informational label.