Chapter 14 - Lighting

14.6. Power Service

The lighting designer shall contact the power company and determine the availability of power service for lighting.  A request shall be made to obtain the power service at locations desired by the lighting designer.  The lighting designer shall provide the power company with information for estimated load at each service point location.  A lighting site visit to meet with a power company representative may be necessary to coordinate power service for a roadway lighting project.

The lighting designer shall coordinate with the power company and the local government or jurisdiction responsible for paying the utility bills to determine if the power services will be metered.  If the local government enters into a contract with the power company to provide power at a fixed monthly charge, light metering will not be required.

The standard power services available from the power company are as follows:

• Single phase – 3 wire: 120/240V and 240/480V, the latter is preferred.

• Three phase – 4 wire: 480/277V.  This power service is preferred when available for lighting projects with large loads.

The electrical power distribution design shall meet the National Electrical Code and local codes.  The power company may want to provide lighting contactors and photocells to control the lighting when the power service is not metered.  In this case, the lighting designer shall include lighting contactors and photocell in the design to control the unmetered lighting system.

All the electrical equipment, such as main circuit breakers, lighting contactors and load centers, shall be in NEMA-4X stainless steel enclosures that can be padlocked and shall be U.L. listed.  A surge suppressor shall be provided at each power service.  The surge suppressor shall be in NEMA-4X enclosure, UL1449 and UL1283 listed suitable for connection to the power service.  The surge suppressor shall have a minimum surge current rating of 130,000A per phase and shall be provided with status indicating lights.

 

The electrical equipment and distribution system shall be designed to take into account any possible future expansion.  The electrical equipment short circuit ratings shall exceed the available fault current.  The lighting designer shall obtain the available fault current values from the power company.

 

The lighting designer shall size all the cables to limit the voltage drop to approximately 3.5%; and in no case more than a 5% drop in power service voltage.  The voltage drop calculations shall be submitted to GDOT for approval.

 

The lighting designer shall include a diagram of each service point. See Figure 14.2, Example of  Service Point Single Line Diagram, for an example of format and content.