One-Line Diagrams

Site Survey

Performing an on-site survey of your electrical system is the first step to creating or updating a single-line diagram. Trained Vertiv™ technicians collect information to determine the elements that need to be deleted or added in the overall schematic. Doing this creates a building block of knowledge. Once the survey is complete, our team will create a new, professional single-line diagram for your records. The site survey services are as follows: 

• Inventory all equipment
• Confirm all loads connected to emergency/standby feeders
• Verify potential single-points of failure
• Evaluate overall system design and determine whether the system can be maintained without shutdown
• Verify that a process to maintain up-to-date drawings is in place
• Update customer-provided single-line diagrams and provide an AutoCAD formatted version
• Provide a report of findings with any recommended actions

Single-Line Diagram Development

The single-line diagram is the blueprint for electrical system analysis. It is the first step in preparing a critical response plan, allowing you to become thoroughly familiar with the electrical distribution system layout and design in your facility. A typical diagram will include:

• Incoming lines showing voltage and size
• Incoming main fuses, potheads, cutouts, switches, and main/tie breakers
• Power transformers (rating, winding connection and grounding means)
• Feeder breakers and fused switches
• Relays (function, use and type)
• Current and/or potential transformers with size, type and ratio
• Control transformers
• All main cable and wire runs with their associated isolating switches and potheads (size and length of run)
• All substations, including integral relays and main panels with total load of each feeder and each substation
• Critical equipment voltage and size (UPS, battery, generator, power distribution, transfer switch, computer room air conditioning)

Single-Line Diagram Review and Update

Following a site survey, Electrical Reliability Services engineers will update existing single-line diagrams or complete electrical system drawings as needed. This update will incorporate any changes to the infrastructure, note load changes, add missing components, and correct inaccurate information.

Compliance and Safety Check

Many electrical systems transform over time, causing concern for safety issues. That’s why NFPA 70E requires an accurate single-line diagram for each facility. Our staff of highly trained professionals put their end-to-end expertise and knowledge of electrical industry code regulations to use to ensure compliance and safeguard your business.