What is Objectionable Current?
The term "objectionable current" in the context of the Philippine Electrical Code (PEC) refers to the presence of current flow on grounding conductors or grounding paths that are not intended to carry current during normal operation.
The PEC addresses objectionable current in Article 2.50.1.6, which highlights the need to minimize or eliminate such currents because they can:
1. Interfere with the normal operation of equipment: This includes electronic devices that are sensitive to electromagnetic interference caused by currents on grounding conductors.
2. Pose a safety hazard: Grounding conductors are primarily intended for fault-current pathways and bonding, not to carry current continuously. Objectionable current could increase the risk of electric shock or overheating.
Key Points from PEC Article 250.1.6:
1. Causes of Objectionable Current:
- Improperly grounded or bonded equipment.
- Parallel paths for neutral current (e.g., when neutral conductors and grounding conductors are connected at points other than the service disconnect or main bonding jumper).
- Inductive coupling between circuits.
2. Permissible Actions to Address Objectionable Current:
The NEC permits certain modifications to eliminate objectionable currents, such as:
- Disconnecting a bonding jumper.
- Changing the location of the grounding connection.
- Adjusting or isolating the grounding and bonding system.
3. Prohibition of Neutral-Ground Connections in Subpanels:
To prevent objectionable current, the PEC mandates that neutral conductors must be isolated from the grounding system in subpanels. Neutral-to-ground conPECtions are only permitted at the service disconPECt or the source of a separately derived system.
4. Notable Exceptions:
Some low-level leakage currents on equipment grounding conductors (e.g., from filtering circuits in electronic equipment) are not considered objectionable if they are within acceptable limits.
Eliminating Objectionable Current - Why is it Important?
Eliminating objectionable current ensures compliance with the PEC and promotes system reliability, safety, and proper equipment performance.