The American Public Works Association (APWA) specifies a uniform color code for the temporary marking of underground utilities, which is essential for safety during excavation. This system is a core component of the "Call 811" process nationwide.
The standard colors are: Red for electric; Yellow for gas, oil, or steam; Orange for communications/CATV; Blue for potable water; Green for sewer/drain lines; and Purple for reclaimed water or irrigation. Pink is used for temporary survey markings and White indicates a proposed excavation area.
These colors are used for both spray paint and the utility sign markers that are placed in the ground. Using clearly identifiable vinyl stake flags is a standard practice. Facilities can also use custom utility marking flags that include their company name or contact information for added clarity.
For permanent utility marker posts, installation depth is key to ensuring long-term stability against weather and frost heave. While local requirements can differ, a general best practice is to install posts a minimum of 24 inches deep in normal soil. For loose or sandy soil, or in areas with deep frost lines, a depth of 36 inches is recommended.
This ensures the post remains secure and upright. Federal regulations, such as 49 CFR 192.707 for gas pipelines, simply state markers must be "placed and maintained" to be visible. Using durable hardware like pole tag markers and holders along with embossed aluminum characters ensures the marker's message is as long-lasting as its installation.
Permanent utility markers must display specific information to comply with regulations and ensure safety. For regulated utilities, this includes: the type of utility (e.g., "Natural Gas Pipeline"), the name of the owner or operator, and a phone number to contact in case of an emergency.
Crucially, all markers for any buried line should feature the "Call 811 Before Digging" warning, which directs all excavators to the national Call 811 one-call system. This essential information is featured on call before you dig signs, including specific ones like an underground gas line warning sign. You can also reinforce this safety message by providing field crews with a "Call Before You Dig" wallet card.
The spacing of permanent utility markers is determined by the goal of maintaining a clear "line of sight" along the utility's path. As mandated by the Pipeline and Hazardous Materials Safety Administration (PHMSA), you should be able to see the next marker from the previous one.
While this often translates to intervals of 200 to 500 feet on long, straight runs, it is more critical to place pipeline signs at every road crossing, railroad crossing, water crossing, and at all major changes in direction. These markers, such as underground live wire signs or no digging signs, are vital for providing warning at the most high-risk locations.
Yes, for certain high-priority utilities, permanent markers are a federal legal requirement. The Code of Federal Regulations (49 CFR 195.410), for instance, mandates the installation and maintenance of line markers for hazardous liquid and carbon dioxide pipelines. Similar rules (49 CFR 192.707) apply to natural gas transmission lines.
These laws require markers at all road, railroad, and water crossings. While requirements for other utilities like water or telecom can vary by state, installing buried cable signs and underground gas line danger signs is a universal best practice and a critical part of your call before you dig safety program to prevent catastrophic accidents.
Striking an underground utility line or hitting a live overhead power line during excavation or construction can cause severe injury or death due to an explosion, fire, or any other accident. Alert workers to these hazards by marking them clearly with our Utility Sign Markers.
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