Philippine Electrical Code – Working Spaces
Working space generally applies to the protection of the worker. Dedicated equipment space applies to the space reserved for future access to electrical equipment and to the protection of the …
Philippine Electrical Code – Metal Underground Water Pipe as Grounding Electrode
The Philippine Electrical Code allows a Metal Underground Water Pipe as a grounding electrode. 2.50.3.3(A)(1) Metal Underground Water Pipe. A metal underground water pipe in direct contact with the earth …
Advantages of High Resistance Grounding Over Ungrounded Systems
A system grounding or earthing method provides the safety, reliability, and continuity of service required by the electrical power distribution system. In the past, ungrounded systems were preferred when reliability …
Why Use IT Earthing System?
Introduction The standard IEC 60364 have used the following nomenclature to specify types of earthing: First letter – Relationship of the power system to earth: T = direct connection of …
Calculating Flash Protection Boundary Distances
In NFPA 70E, the short-circuit symmetrical ampacity from a bolted 3-phase fault at the transformer terminals is calculated with the following formula: where Isc = Amperes, V = Volts, %Z …
Arc-Flash Hazards
An arc-flash is a release of energy caused by a flow of fault current through an electrical arc plasma. Arc flashes can occur when racking a breaker in/out, removing a …