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One-call systems


Inadvertent damage to existing underground pipes and cables and associated utilities is a very real hazard to workers and the general public.  A one-call communication system has been established nationwide to link excavators and utility owners/operators.  Most local and/or state laws now require that a one-call center be notified prior to excavating.  Typically, at least a 48-hour notice is required; however, this may vary according to state and/or location.

This technical bulletin describes the excavator’s and utility owner’s responsibilities in coordinating excavation projects and underground utilities. It also lists the uniform color code for underground utilities and provides a telephone directory for one-call systems.

Excavator’s Responsibilities

Facility Owner’s Responsibilities

Multiple One Call centers or “Call Before You Dig” centers exist throughout the United States.  In an effort to eliminate confusion over what number homeowners and professional excavators should call before digging, the Federal Communications Commission has approved the number 811 to serve as a national “Call Before You Dig” phone number.  Calls to 811 will route to the local One Call center and the affected utilities will then mark any underground lines at no charge.  The 811 number is designed not as a replacement for the state-specific “one-call” numbers already established, but to serve as a hub to forward callers to the correct center in their area.

State-specific 811 numbers


29 CFR part 1926.651(b).
One-Call System Directory.
Call 811.

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