Walk the building.
Standards are organised by subject. Facilities are organised by room. This is the translation — what applies where you are actually standing, laid out the way the power actually flows.
Nobody stands in the middle of Article 130. They stand in a switchgear room at 2 a.m. with a work order. Every page in this section answers the same five questions for one space: what are the hazards, which sections apply, what PPE, who may be in here, and what goes wrong.
§ The facility map
Follow the energy. Every block below is a space you can stand in, coloured by the electrical risk you meet there.
Risk here is not the same as voltage. The data hall is the lowest-voltage electrical space in the building and it is marked mixed, because the people working energized equipment there are frequently not qualified persons. The construction boundary is marked high because three standards apply on the same slab at the same time.
§ The power path
Switchgear & ATS rooms
The highest available fault current in the building, protected by the slowest upstream device. Racking a breaker is the single highest-risk routine task on site.
UPS rooms
Five sources minimum — input, output, static bypass, maintenance bypass, DC bus. Bypass is an availability action, not a safety action.
Battery rooms
The densest hazard concentration in the building. Four categories in one room under Article 360, plus NFPA 855 for lithium — and you cannot lock out a battery.
Data hall / white space
The room everyone thinks is the safe one. Full of energized equipment, worked mostly by people who are not qualified persons, at hot-aisle temperatures.
Generator yard
The only major equipment in the building designed to start without a human deciding to start it. Everything about working there follows from that.
§ Mechanical, support and the outside
Chiller plant, pumps and cooling towers. Medium-voltage motors, rotating equipment guarding under 1910.212, confined-space basins, chemical treatment, and legionella. Page in build.
AHU and fan wall galleries. Machine guarding, VFD DC bus stored energy, and access at height inside the gallery. Page in build.
Roof. A working floor carrying chillers, condensers, dry coolers, exhaust and often PV — at the 4-foot general industry trigger, with an unprotected edge somewhere. Subpart D →
Vaults, pits and manholes. Permit-required confined space and energized medium-voltage cable, simultaneously. 1910.146 →
Loading dock and staging. Powered industrial trucks, dockboards, and every rack in the building arriving through it. Page in build.
MDF, IDF and meet-me rooms. DC power plants at 48 V — below the shock threshold, well above the contact thermal threshold. Page in build.
NOC and offices. Egress, emergency action plan, and the people who will be told first when something goes wrong. Page in build.
§ The edge nobody writes about
The construction zone adjacent to live space is the highest-risk area in this industry and the one with the least written about it. A fit-out crew installing a new data hall is working thirty feet from energized 480 V distribution serving a live customer.
Three standards apply on that slab at the same time: 1926 for the construction crew at a 6-foot fall trigger, 1910 for the operations technician at 4 feet, and NFPA 70E for any gear that has been energized — regardless of whether the project is finished.
§ How to use this section
Before a job. Open the space page, not the standard. It tells you what applies here and what tends to go wrong here.
For a job briefing. The hazard tags on each card are a ready-made briefing checklist for that room — 110.3(I)(1).
For onboarding. Walk a new technician through the map in order. It is the fastest way to build a mental model of where the energy is.
For contractor orientation. The 110.5 information exchange has to cover known hazards by location. This is that document.
Onsite classes include a facility walkthrough
Where the site permits, the class walks your switchgear room, UPS room and battery room — against your one-lines and your labels.
Onsite training Get in touch