The article for equipment that does not exist yet.
Most of NFPA 70E assumes listed equipment installed to a code. Article 390 covers the places where that assumption fails — laboratories and R&D areas full of custom or special electrical equipment that was designed in-house and exists in a quantity of one.
390.1 applies to the electrical installations in those areas, with custom or special electrical equipment, designated by the facility management for research and development or as laboratories. Note who draws the boundary: not the code, not an inspector — facility management designates the area.
§ How it sits against the rest of the standard
390.3 is the hinge. The electrical system for R&D and laboratory applications shall meet the requirements of the remainder of this document, except as amended by Article 390. It is an overlay, not a carve-out — everything still applies unless this article changes it.
The Informational Note lists what the committee had in mind, and the range is wide:
- Low-voltage, high-current power systems.
- High-voltage, low-current power systems.
- dc power supplies and capacitors.
- Cable trays for signal cables and other systems — steam, water, air, gas or drainage.
- Custom-made electronic equipment.
§ The Electrical Safety Authority
390.4 introduces a mechanism that appears nowhere else in the standard.
Assignment. Each laboratory or R&D system application shall be permitted to assign an Electrical Safety Authority (ESA) to ensure the use of electrical safety-related work practices and controls.
Members. The ESA shall be permitted to be an electrical safety committee, an engineer, or an equivalent qualified individual.
The ESA is the standard’s answer to a real problem: when equipment is one-of-a-kind, there is no manufacturer’s instruction, no listing, and no label to rely on. Someone competent has to make the call locally and own it. Note the permissive language — shall be permitted to assign. It is an option the standard offers, not a duty it imposes, which means a lab that would benefit from one has to choose it deliberately.
This lands harder on hyperscale campuses than it first appears. Test cells, burn-in halls, prototype labs, power-electronics benches and commissioning mock-ups are exactly the "custom or special electrical equipment" the article describes — and they are common at the operators building their own hardware.
The equipment in those rooms is frequently a custom dc supply or a capacitor bank, which pulls Article 310 and Article 320 in alongside this one.
Watch the renumbering. This was Article 350 in the prior edition, and Article 350 now means electrolytic cells. A lab safety program citing "Article 350" is now pointing at chlor-alkali plants.