Idaho Power’s Rule K: Customer’s Load and Operations Tariff, approved by the Idaho Public Utilities Commission (IPUC) and the Public Utility Commission of Oregon (OPUC), explains customer responsibilities that help maintain safe, reliable service. These responsibilities  include: 

• Using equipment that does not interfere with service to other customers 

• Managing harmonics to help maintain power quality 

• Letting Idaho Power know before making major changes to your electrical equipment 

• Protecting your own electrical equipment 

• Following requirements for motors larger than 7½ horsepower 

Following Rule K helps support reliable power for your facility and your community. 

Rule K applies to all Idaho Power customers. Harmonics are usually a concern for larger commercial, industrial, and irrigation customers. 

Harmonics are electrical frequencies that are higher than the standard 60 Hz power delivered by Idaho Power. Some electronic equipment creates these frequencies as it operates.  

Too much harmonic current can: 

• Create excess heat in electrical equipment  

• Reduce power quality 

• Interfere with sensitive electronics 

• Damage customer-owned and utility-owned equipment. 

To help protect the electric system, Rule K requires customers to limit the harmonics their equipment produces and comply with the Institute of Electrical and Electronics Engineers (IEEE) Standard 519.  

Many electronic devices can create harmonics, including some energy-efficiency equipment. These devices include: 

• Variable-frequency drives (VFD) used with electric motors 

• Power converters (alternating current [AC] to direct current [DC] voltage)  

• Arc discharge equipment 

• Induction arc furnaces 

• Overvoltage transformers and some rotating machines  

• Compact fluorescent lighting 

• Electronic lighting ballasts 

If you use equipment that generates harmonics, you may need to install filters or other harmonic-control equipment. These can help protect your equipment, improve power quality, and meet Rule K requirements. Contact your electrical equipment supplier to learn about available options. 

If testing shows your equipment does not comply with Rule K, you will have up to one year to make corrections.  Idaho Power will work with you to help ensure you meet the requirements of Rule K.