Festival temporary service — Article 525, drawn at scale.

The shape of a temporary service

A festival temp service comes in three forms. The first is a utility temp drop: Nashville Electric Service (or the equivalent regional utility) sets a temporary pole or pad-mount transformer and lands a 200 A through 1,200 A service drop for the duration of the event. The temp drop is metered; the cost runs $0.04–$0.06 per kWh plus the per-day demand charge. The advantage is reliability; the disadvantage is the AHJ paperwork and the lead time (NES requires 30 working days for new temp service in metro Nashville).

The second is generator-only service: paralleled diesel sets, sized to the event load with 25% headroom, on a graveled pad with NFPA 110 distance-to-occupancy clearances. We work this configuration regularly on county-fair grounds and parking-lot events where there is no utility infrastructure within reach. Generator-only also gives us full control over ground-fault detection — we know the source impedance because we tuned it at the easYgen.

The third is hybrid: utility primary, generator backup. The utility service runs the show under normal conditions, and a paralleled gen bank stands ready on auto-start at the ATS. The hybrid configuration is required by some venues (CMA Fest at Riverfront, Bonnaroo at Great Stage Park) where the utility is theoretically reliable but a single transformer failure can lose six stages, and the backup must come up inside the NFPA 110 Type 60 cycle (60 seconds to full load).

Pole-mount disconnect, visible break

Every temp service has a pole-mount disconnect at the service entrance. We use Eaton CFP-series fused disconnects in NEMA 3R enclosures for outdoor service; visible-break, padlockable, color-coded for the AHJ inspection. The disco lands at chest height on a 4×4 pressure-treated post set in a base of 2,000 psi concrete or sandbagged for ground-mount installations. The fuse rating matches the service ampacity within one trade size.

From the disconnect, 4/0 Type W feeder runs to a head-end distro on a road case. The head-end splits the load into 200 A and 100 A sub-distros at each stage. We label every conductor at the disco and at the sub-distro with a printed strap (BSP-{tour-no}-FEEDER-A1 through A5). Metro Codes requires a written single-line diagram on file at the dispatch tent during the event; we keep two copies, one in the binder and one taped inside the disco enclosure door.

GFCI on every public-accessible receptacle

NEC 525.23(A) requires GFCI Class A protection on every 15-A and 20-A 125-V single-phase receptacle used by personnel.¹ We exceed the standard — every public-accessible receptacle on every festival site gets GFCI, including 30 A locking receptacles for vendor booths, and including the 50 A range receptacles on food trucks that are commonly miswired. We use inline GFCI modules (rather than receptacle-replacement units) so the GFCI assembly is part of the cable rather than the structure; it travels with the cable, it gets Megger-tested with the cable, and it is part of the daily trip-test cycle.

Trip-test cycle: at 08:00 every morning of the event, the lead electrician on call walks every GFCI on the site with a Wiggy-type tester and presses the test button. Trip is verified by audible click and by a re-test (a tripped GFCI does not pass a re-test until reset). Failures are documented in the green daily-log book at the dispatch tent. We have replaced inline GFCIs on the site twice — once at a 2022 county fair in Wilson County (a unit had been crushed by a truck overnight) and once at CMA Fest 2024 (a unit had taken on water in a 4 AM rain). Both replacements were inside 30 minutes.

Daily logs — Megger, GFCI, phase rotation, ground-rod

Article 525 doesn’t require a daily log; we keep one anyway, because the AHJ walks the site daily and asks for it. The log is a green-bound book sitting on the dispatch tent table; it has four columns each day:

1. Megger reading at the head-end distro, 500 V DC, one minute. Action limit 1,000 megohms; healthy reading above 5,000 megohms.
2. GFCI trip-test at every public-accessible receptacle. Pass / fail / replaced. Initialed.
3. Phase-rotation verification at the head-end and at each stage distro. ABC / verified.
4. Ground-rod resistance at the service entrance, measured with a Fluke 1623-2. Action limit 25 ohms (NEC 250.56); we shoot for less than 5 ohms with rod augmentation.

The log is signed at end of shift by the lead electrician and at end of event by the AHJ. The book sits on the shelf at the bay door at the end of every cycle; we have a stack of fourteen volumes, one per year of operations, with the oldest book’s ink fading slightly.

Distance, height, ramps, ribbons

Cable that crosses a pedestrian path is in ramps; cable that crosses a vehicle path is in trench plates or buried. Article 525 doesn’t specify clearances; OSHA 1926 Subpart K requires guards against accidental contact, and the trade vernacular is clear: yellow ramps over walked-over cable, trench plates over vehicle-crossed cable, ribbons over either if foot traffic is heavy or visibility is poor. We carry forty 4-foot ramps in the truck, six trench plates rated to 15,000 lb gross vehicle weight, and a roll of orange ribbon long enough to do the entire CMA Fest Riverfront stage circuit.

Overhead cable spans (across roads or vendor lanes) get clearance per NEC Article 225 Table 225.18: 12 feet over residential driveways, 18 feet over commercial driveways, 18 feet over public ways subject to truck traffic. We measure with a fiberglass measuring stick at every span. We have raised a span three times in nine years; each time we caught it ourselves on the daily walk before the inspector.

Permit, walk-through, inspection

Every festival temp service requires a Metro Codes temp electrical permit. We apply at nashville.gov/departments/codes 10 working days before load-in; the application requires a single-line diagram, a site plan with cable routes, a load calculation per NEC 525.20, and a fee scaled to the service amperage. The AHJ inspector schedules a walk-through at tie-in; the walk-through is mandatory and we will not energize the service without the inspector’s sign-off on the permit card.

For events outside Davidson County, the local AHJ governs. Shelby County (Memphis) requires its own permit; Knox County (Knoxville) accepts the same documentation; Williamson County (Brentwood/Franklin) has its own form. We keep the application templates for the eight regional AHJs we work with in a binder at the bay; the templates are updated quarterly.

Lead time, price, and the way to book

Lead time is ten working days for any festival temp service (driven by the AHJ permit window), longer if the service requires NES coordination. Price band is $8,400 (a single-stage event, 200 A service, two-day run) to $96,000 (a multi-stage festival with paralleled generator backup, daily logs, dispatch tent staffing, and 24-hour on-call for the duration). Permit fees are passed through at cost.

For booking, send the site plan, expected attendance, single-line load calc, and load-in date via /advance/. We will not bid a festival temp without a site visit at least once before the proposal.