Understanding NFPA 70, Article 590: Temporary Electrical Installations

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The NFPA 70, also known as the National Electrical Code (NEC), is a comprehensive set of electrical standards and guidelines aimed at ensuring electrical safety across various installations. Among its many articles, Article 590 specifically addresses temporary electrical installations. In this article, we will provide a basic overview of Article 590, highlighting its key principles and why compliance is crucial for safety, whether at a construction site, a special event, or any other temporary location.

1. Temporary Installations and AHJ Approval: Article 590 emphasizes that temporary installations are only considered temporary when approved by the Authority Having Jurisdiction (AHJ). This approval is essential, as it ensures that temporary installations meet the necessary safety standards.
2. Broad Applicability: Article 590 is not limited to one specific type of temporary location. It applies to any temporary installation, whether it's at a construction site, a store parking lot, or even a local craft fair in a field. This versatility underscores its importance in various scenarios.
3. Adherence to Permanent Installation Requirements: One significant aspect of Article 590 is that temporary electrical equipment must be installed following all applicable permanent installation requirements, except as modified by the rules within this article. For instance, splicing requirements are modified to accommodate construction sites, allowing splices to be made in multiconductor cords and cables without the use of a box.
4. Safety Over "Temporary" Convenience: The article stresses the importance of not dismissing NEC requirements simply because the installation is temporary. Safety should never be compromised, and all installations must adhere to the code, whether temporary or permanent.
5. Grounding and Rod-Type Electrodes: Article 590 highlights that temporary services must be grounded in the same manner as permanently installed services. Rod-type electrodes, for instance, must meet specific requirements, including the need for a supplemental electrode, unless the earth resistance condition is met.
6. Electrical Accidents Know No Boundaries: The article underscores that electrical accidents can occur in any installation, temporary or permanent if NEC requirements are not followed. Due to the nature of work at construction sites, following Article 590 is essential for electrical safety.
7. Special Requirements and Time Limits: Temporary electrical power and lighting installations are generally permitted for up to 90 days for holiday decorative lighting and similar purposes. However, exceptions apply, and some projects may require longer temporary power solutions.
8. Flexible Wiring Methods: Article 590 allows for the use of nonmetallic jacketed cables and flexible cords for temporary branch circuits and feeders, including Types NM, NMC, and SE cable.
9. Ground-Fault Protection: Ground-fault protection is a critical aspect of temporary wiring installations. The article outlines specific requirements for receptacle outlets used for temporary power and highlights the importance of GFCI protection.
10. Inspection and Maintenance: Temporary electrical equipment, often exposed to harsh conditions, must be regularly examined before being put back into use. Specific requirements for overcurrent protective devices (OCPDs) are also outlined to enhance safety.

The NFPA 70, Article 590, plays a crucial role in ensuring the safety of temporary electrical installations. Whether you're setting up temporary power at a construction site or arranging holiday lighting, compliance with the NEC is essential to protect users from electrical hazards. Understanding the principles outlined in this article can help ensure that temporary installations meet safety standards and prevent accidents. Remember, safety always comes first, regardless of whether an installation is permanent or temporary.