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g/electrical • Posted by u/conduit_king •

Finished a 3000A switchgear replacement in a live hospital — 14 hour window, zero unplanned outage Job Photos

Wrapped this two weekends ago and I am still coming down off it. 1978 switchgear feeding half a hospital campus, bus insulation failing, no replacement parts in existence.

The plan:

Weeks 1-6 — build the temp feed. 2000A of cam-lock from a rental 2MW genset into a temporary distribution section, tested and load-banked twice before we touched anything live.

Window — Saturday 18:00 to Sunday 08:00. Transfer to temp, demo, set new gear, terminate, test, transfer back.

Actual — transfer at 18:40, gear out by 22:15, new gear set and anchored by 01:30, terminations done at 05:10, megger and phase rotation by 06:20, retransfer at 07:05. Fifty-five minutes to spare.

The thing that made it work was not the schedule, it was that we ran the whole retransfer as a written sequence with one person reading and one person executing, out loud, like a checklist. Nobody touched anything that was not read aloud first. Sounds slow. Was not.

Six months of planning for fourteen hours of work. Worth every meeting.

💬 7 replies

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u/admin_jake ADMIN •

The read-aloud switching order is how the utilities have done it for eighty years and it is still the single highest-value practice in energized work. Everybody who skips it does so because it feels bureaucratic right up until the day it saves them.

Beautiful work. That old bus looks like it was three months from finding out on its own.

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u/vfd_victor •

Load banking the rental twice before the window is the part people cut when the schedule tightens, and it is the part that ends the job if you skip it. A genset that has not been proven under real load is a rumor.

What did you use for the temp distribution section, rental or shop-built?

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u/conduit_king OP •

Rental. We looked hard at building one and the numbers were close, but the rental came with a current cert and a spare, and on a hospital job the spare is worth more than the savings.

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u/gen_set_gina •

Hospital work has a wrinkle a lot of people miss — NFPA 99 essential electrical system branches have to stay separated the whole way through the temp arrangement. You cannot just bulk-feed everything off one temp bus and sort it out later. Did the temp section maintain life safety, critical and equipment branch separation?

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u/conduit_king OP •

It did, and that drove the whole design. Three separate temp sections, one per branch, individually metered. It was the expensive way to do it and the AHJ and the hospital's own safety officer both asked about it before they asked about anything else.

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u/osha_omar •

Reading this as the safety guy: fourteen hours is a long window for energized adjacent work and crews make their mistakes in hours ten through thirteen. How did you handle relief? Straight through or rotating?

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u/conduit_king OP •

Two crews, hard swap at 00:30, and the incoming crew got the sequence briefing before the outgoing crew left the floor. Nobody worked the full fourteen. That was a lesson from a job about five years ago that I would rather not describe in detail.

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