Electrical One-Line Development:

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Power Systems & Controls can conduct a comprehensive site survey to create an Electrical One-Line Development for your power “backbone”.

The accuracy of this diagram is extremely important and will impact the decisions being made by maintenance staff or Engineering. Electrical design changes, additions, modifications or just electrical trouble shooting depend on an up-to-date One-Line Diagram.

A one-line diagram, sometimes referred to as a “single-line-diagram”, is not only an overview of your power flow, but also serves as the “Master” document for your facilities electrical distribution system and depending upon the detail, the power Engineer can determine specific loads, with just a glance. This diagram is necessary to complete many of the tasks that will be required during the year, as well as, over the life of your facility

One Line Sample

The One Line Diagram can be drawn in many levels of detail, from main distribution loads all the way to wall outlets and locations.  Therefore, if you were a facility engineer looking to control a specific circuit, this diagram would save you time and allow you to avoid impacting the wrong load, or better stated, turning off the power to a critical load inadvertently, which might result in a loss of time and money.  The diagram could also allow Engineering to calculate load growth, determine critical spares, and plan for alternate power paths available during scheduled plant outages.  Again, this diagram is critical when making changes to the power anywhere downstream of the main distribution to ensure breaker coordination and fault current are not ignored.

NFPA-70E requirements mandate accurate, up to date one lines. OSHA or VOSH uses this as reference.

Electrical One-Line Development:


  • Layout of all major connected loads
  • Inventory of distribution equipment
  • Future plans for equipment and loads
  • Critical and non-critical load busses
  • Road map or quick snapshot of your power "Backbone" when looking for problem areas
  • Main entrance power thru distribution switchboards and possibly to connected loads


  • Short Circuit Studies
  • Coordination Studies
  • Arc Flash Evaluations
  • Grounding Assessments


  • Allows Troubleshooting of the Power Path
  • Allows Facility Safety Training
  • Decreases Insurance Premiums (NFPA 70E)