Section 2.25.2.1 of the Philippine Electrical Code specifies that incoming supply to a building or other structure shall be supplied by only one feeder.
2.25.2.1 Number of Supplies. Number of Supplies. A building or other structure that is served by a branch circuit or feeder on the load side of a service disconnecting means shall be supplied by only one feeder or branch circuit unless permitted in 2.25.2.1(A) through (E). For the purpose of this section, a multiwire branch circuit shall be considered a single circuit.
Where a branch circuit or feeder originates in these additional buildings or other structures, only one feeder or branch circuit shall be permitted to supply power back to the original building or structure, unless permitted in 2.25.2.1(A) through (E).
What are the Exceptions?
- (A) Special Conditions.
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- Fire pumps
- Emergency systems
- Legally required standby systems
- Optional standby systems
- Parallel power production systems
- Systems designed for connection to multiple sources of supply for the purpose of enhanced reliability
- Electric vehicle charging systems listed, labeled, and identified for more than a single branch circuit or feeder
- (B) Special Occupancies.
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- Multiple-occupancy buildings where there is no space available for supply equipment accessible to all occupants
- A single building or other structure sufficiently large to make two or more supplies necessary
- (C) Capacity Requirements.
- Additional feeders or branch circuits shall be permitted where the capacity requirements are in excess of 2000 amperes at a supply voltage of 1000 volts or less.
- (D) Different Characteristics.
- Additional feeders or branch circuits shall be permitted for different voltages, frequencies, or phases, or for different uses such as control of outside lighting from multiple locations.
- (E) Documented Switching Procedures.
- Additional feeders or branch circuits shall be permitted to supply installations under single management where documented safe switching procedures are established and maintained for disconnection.
Exception Examples
Buildings on school campuses, multi-building industrial facilities, and multi-building commercial facilities are permitted to be supplied by secondary loop supply (secondary selective) networks if documented switching procedures are established. The switching procedures must establish a method to safely operate switches for the facility during maintenance and during alternative supply and emergency supply conditions. Keyed interlock systems are often used to reduce the likelihood of inappropriate switching procedures that could result in hazardous conditions.