Electrical Report

1. Purpose

This report specifies the complete electrical and environmental control systems for TBS-001: solar power architecture, battery bank, light trap vestibule, cooling, ventilation, interior lighting, and wiring. All systems run at 12V DC from a solar array with optional shore power backup, enabling fully off-grid operation.

See also: Operating Manual for step-by-step operational procedures.

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2. System Overview

TBS-001 is designed for fully off-grid operation. All power comes from a solar array charging a LiFePO4 battery bank. Shore power (grid AC) is accommodated as an optional backup charging input only — the system operates identically without it.

All loads run at 12V DC - the one exception is the dedicated Circuit-E cooler inverter — see §7.6.

Interactive 3D model — the solar array, the panel internals (MPPT / fuse block / busbars / disconnects), the battery, the external power panel, the Circuit-E inverter, and the color-coded circuit runs out to each load. Drag to orbit, scroll to zoom.

TBS-001 Electrical Model by alvin91403 on Sketchfab

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Sheet 7 — System Schematic (Symbol Diagram) The whole 12V DC system as a traditional symbol-based electrical schematic — every conductor traced from the PV array through the MPPT, battery, 200A MRBF, contactor K1, and main disconnect to the Blue Sea 5026 bus and the seven load circuits (A–G), with the NC E-stop loop and shore charger shown explicitly.

3. Power Budget

Circuit	Device	Peak draw	Duty cycle
A	Ventilation fan — exhaust (6")	60W	Continuous during processing
B	Ventilation fan — intake (6")	60W	Continuous during processing
C	Water pumps P-01–P-05 (12V DC; 5× Shurflo 2088, run one at a time; single master switch)	100W (one pump)	Intermittent (~30 min/print)
D	Safelight — interior + vestibule	40W	Loading phase only (~45 min)
E	Evaporative cooler — Hessaire MC18M (120V AC) via 12V→120V inverter	97W on 12V bus	Continuous during operation
F	Film plane actuators (optional)	100W peak	Intermittent
G	White LED strip ×3 (general lighting)	~76W	Non-operational periods only
Total peak (all on)		533W	Not all simultaneous

Circuit E is the only AC load. The cooler is a commodity 120V AC swamp cooler driven by a dedicated 12V→120V pure-sine inverter; its 85 W AC draw is 97 W on the 12 V battery bus (÷0.88 inverter efficiency). See §7.6 AC Isolation & Safety for the grounding/GFCI design.

3.1 Itemized Energy Budget (per print session)

Continuous loads by phase:

Phase	Min	Active circuits	W	Wh
1.6 Cooling warmup	30	Fan A (exhaust), Fan B (intake), Evap cooler	217	108
1.7–1.8 Dark adaptation	20	Fan A (exhaust), Fan B (intake), Evap cooler, Safelight	257	86
2 Load image plane	45	Fan A (exhaust), Fan B (intake), Evap cooler, Safelight	257	193
3 Exposure	37.5	Fan A (exhaust), Fan B (intake), Evap cooler	217	136
4 Development & wash	20	Fan A (exhaust), Fan B (intake), Evap cooler, White light	293	98
5 Cleanup	30	Fan A (exhaust), Fan B (intake), Evap cooler, White light	293	146
Subtotal	182			767

Intermittent loads (total runtime per print):

Item	W	Min	Wh
Pumps (P-01 Blue)	90	15	22.5
Pumps (P-02 Brown)	90	10	15.0
Pumps (P-04 drain)	90	5	7.5
Actuators (optional)	100	5	8.3
Subtotal			53

Total energy per session: 820 Wh (0.82 kWh)

Battery bank capacity (standard build, 1 pack): 100 Ah × 12V = 1,200 Wh (LiFePO4, 100% DoD) → 1.5 sessions per charge. The distribution busbar + fuse block are provisioned for a 2nd 100 Ah pack in parallel — a plug-in expansion (→ 200 Ah / 2,400 Wh / 2.9 sessions) requiring no rewiring; the 2nd pack is shown ghosted in the 2D/3D models.

Solar recharge: 600W array × 5.5 peak sun hours (Palm Springs) = 3,300 Wh/day → supports 4.0 sessions/day from solar alone.

3.2 Daily Use & Disconnected Endurance

Full treatment in the Daily Energy Report.

A representative daylight day of 3 sequential prints draws ~2,218 Wh (2 prints ~1,515; 4 prints ~2,921), dominated by the continuous fans + evaporative cooler (the cooler now drives the AC inverter, ~97 W on the 12 V bus); the Brown/Waste tote dump is gravity-assisted, tiny (~40 Wh), and incurred only at resupply (~every 4.7 days), not daily.

Disconnected endurance (no AC charge, solar top-up only): the system is clean-water limited, not power limited. With sun it is solar-positive (+1,082 Wh/day at 3 prints) → runs indefinitely on either 1 or 2 packs; the fresh Blue supply (1,800 L / 121 L net per print) caps a deployment at ~15 prints ≈ 4.7 days @ 3/day. Battery count sets only the cloudy-day reserve (1 pack ≈ 0.5 day, 2 packs ≈ 1.1 day) and the 4-print-day headroom — not the deployment length. The Black waste tote (1,000 L) is a parallel out-flow limit for fully self-contained field use.

4. Solar Array

Parameter	Specification
Panels	3 × 200W monocrystalline, 12V nominal
Configuration	3 panels in parallel (12V, 30A combined Isc)
Mounting	Ground-mounted tilt frame (30° from horizontal) or roof rack
Orientation	Due south (azimuth 180°)
Cable	10 AWG PV cable, MC4 connectors
Combiner	3-way MC4 branch connector + 30A inline fuse per string
PV disconnect	Blue Sea 6006 DC battery switch (300 A / 48 V DC — sized against the array's ~30 A / ~22 V, since the panels are 3× parallel at 12 V nominal, not a high-voltage string), readily accessible at the power panel — isolates the array from the MPPT for service/fault (NEC 690.13). MC4 connectors are not load-break rated, and the external E-stop kills only the battery side — this kills the charge side
Wall entry	Via the external power-panel enclosure (§5.4) — the PV cables join the single sealed wall-bundle penetration
Approximate cost	~$400 (panels) + ~$80 (mounting hardware) + ~$34 (PV disconnect — Blue Sea 6006)

Siting: deploy panels on south-facing ground adjacent the container. For example, 30° tilt is optimal at Palm Springs latitude (33°N) for year-round average. If deploying in summer only, increase tilt to 20° for higher peak output.

5. Charge Controller and Battery Bank

5.1 Charge Controller

Parameter	Specification
Model	Victron SmartSolar MPPT 100/50 charge controller
Max PV input	100V OC, 50A charge current
Battery voltage	12V auto-detect
Communication	Bluetooth (Victron Connect app)
Mounting	Interior short wall, adjacent main panel
Charge-line protection	60 A ANL/MIDI fuse on the MPPT→battery lead, close to the battery; charge conductor sized 6 AWG
Approximate cost	~$200 + ~$15 (charge fuse)

The SmartSolar has a built-in load output (30A) for direct low-power 12V loads. The main high-current loads connect via the Blue Sea fuse block (see Section 7).

The MPPT delivers up to 50 A to the battery, so its battery lead carries far more than the array side — a dedicated 60 A fuse close to the battery protects that conductor (the 200 A main fuse is far too large to protect a charge-controller lead), and the conductor is upsized to 6 AWG to match.

5.2 Battery Bank

Parameter	Specification
Chemistry	LiFePO4 (lithium iron phosphate)
Configuration	1 × 100Ah 12V standard (busbar provisioned for a 2nd in parallel → 200Ah; plug-in expansion, no rewiring)
Usable energy	1,200 Wh standard (2,400 Wh with the optional 2nd pack)
Discharge temperature	−20°C to +60°C operating — suitable for the hot container interior
Charge temperature	0–45 °C — the BMS blocks charging above ~45 °C (cell protection); this drives the thermal siting below
Cycle life	3,000–5,000 cycles to 80% capacity
BMS	Internal per-cell BMS (standard on Battle Born, Renogy LiFePO4 units)
Recommended brands	Battle Born 100Ah, Renogy 100Ah Core Series
Approximate cost	~$350 (one unit); +$350 for the optional 2nd pack

Thermal siting (required). Because the BMS inhibits charging above ~45 °C while a sun-exposed steel container can reach 60 °C interior, the pack is mounted low (floor level, in the coolest stratified air), shaded from the sun-baked shell, and kept in the evaporative-cooler / ventilation airflow path — so it stays inside the charge window during peak sun rather than locking out the solar charge. A commissioning temperature check confirms the bay stays < 45 °C under load (see Electrical Safety §4 #4).

One pack vs two — sizing rationale: a disconnected deployment is clean-water limited (~15 prints / ~4.7 days), not power limited (see §3.2), and the system is solar-positive, so one 100 Ah pack runs the standard deployment indefinitely on sun. The 2nd pack is a resilience upgrade — it extends the no-sun (cloudy-day) reserve from ~0.5 day to ~1.1 day and gives headroom for a 4-print day — not an endurance one. It plugs onto the busbar via its own terminal MRBF fuse — each parallel pack is fused at its own + post, so one pack's fault can't be back-fed by the other (the 2/0 cable and main disconnect are already sized for 200 Ah), so it can be added later without touching the wiring.

Why LiFePO4 and not NMC or lead-acid: - LiFePO4 does not exhibit thermal runaway — safe in an enclosed steel container that may reach 60°C interior - Full 100% depth of discharge usable (vs. 50% for lead-acid, 80% for NMC) - 3,000+ cycle life supports frequent deployments without degradation - No outgassing — can be used in an enclosed space without ventilation dedicated to the battery

5.3 Shore Power Backup Charger

Parameter	Specification
Model	Victron Blue Smart IP65 12/15
Input	100–240V AC, NEMA 5-15 (standard US outlet)
Output	12V DC, 15A (180W)
Full charge time from flat	~7 hours standard (100Ah ÷ 15A); ~14h with the 2nd pack
Inlet	NEMA 5-15R weatherproof inlet in external power panel (pinhole wall exterior)
Output protection	20 A fuse on the charger's DC output lead, close to the battery
Approximate cost	~$150 + ~$5 (output fuse)

Connect whenever shore power is available at a deployment site (campground hookup, venue power, generator) to top up the battery bank overnight.

5.4 External Power Panel

The solar PV inputs, shore power inlet, and the evaporative cooler's 120V AC output are carried on a fabricated flanged penetration box let into the pinhole wall, close to the electrical panel and battery bank inside.

Parameter	Specification
Box	Fabricated sheet-metal flanged box — front face (exterior) + exterior flange, open to the container interior
Solar inputs	3 × MC4 bulkhead pairs (IP67) — surface-mounted, sealed to the face
Shore power	1 × NEMA 5-15R weatherproof inlet
Cooler output	1 × NEMA 5-15R weatherproof duplex + in-use (bubble) cover (Circuit E — fed from the interior inverter, GFCI at the inverter §7.6)
Emergency stop	1 × exterior red mushroom E-stop (kills the battery contactor from outside, §7.5)
Wall seal	Flashing + silicone bridging the corrugation crests around the flange — water-tight AND light-tight
PV disconnect	On the EP backboard (Blue Sea 6006, with the main disconnect + master pump switch) — not on this box
Location	Pinhole wall, X ≈ 1,250–1,590mm (just left of EP)
Approximate cost	~$85 (fab box $60–100 + flashing/silicone $15–30)

All four exterior interfaces are already weatherproof (MC4 IP67, weatherproof shore inlet, WR duplex under an in-use cover, IP65 E-stop), so they mount exposed — each surface-mounted and gasket-sealed to the box's front face, with the electrical attached from the container-interior side (the box opens inward). No secondary IP enclosure is needed. The container wall is corrugated, so the box's exterior flange can't seat flat: it is sealed to the wall with flashing over the corrugation crests plus a silicone bead — a seal that must be light-tight as well as water-tight (this is a pinhole camera; any perimeter gap or connector cavity fogs the print). Opaque front face + gasketed opaque devices + flashed flange give the light seal; the inlet/outlet socket cavities get a light-baffle behind them. Each device's wiring runs inside the container to the EP — the PV pairs to the Blue Sea 6006 disconnect on the EP backboard, the shore inlet to the charger, the cooler outlet from the inverter (Circuit E), the E-stop loop to the contactor. The cooler is unplugged and the cord stowed inside for transport. See the power panel detail drawing below.

Detail drawing update to the penetration-box layout is pending (tracked in TODO) — it currently shows the superseded flush-plate geometry.

6. Interior Lighting

6.1 Two-Circuit Lighting Design

TBS-001 requires two mutually exclusive lighting modes:

• Safelight (Circuit D): Red 12V COB LED strip (Super Bright LEDs, in 981 channels + frosted diffuser), ceiling-mounted running near→far wall (X=520 / 2270 / 4170) plus the inner drum face, each shortened to clear the optical cone. Used during loading and development when photosensitive material is present. Red is cyanotype-safe (the process responds only to UV/blue). One 5m reel cut across the runs, ~40W total (3.3A — within the 5A fuse / 18 AWG, no bump), dimmable, always available. (Two of the three ceiling runs carry a parallel white strip — see §6.2.)
• White light (Circuit G): Three 12V COB LED strips (in aluminum channels + frosted diffusers) — two over the tray parallel to the two drum-side red safelights (X=520 / 2270), plus one running the length of the IBC/plumbing corridor to light the plumbing panel — for setup, maintenance, cleaning, and any non-operational work. ~76W total. Must be switched off before any photosensitive material is exposed.

The two circuits are independently switched — they are not interlocked, so the operator is responsible for ensuring Circuit G is off during operational phases. The pull-cord switches are positioned side by side for easy identification.

6.2 White LED Strip Specification

Parameter	Specification
Type	12V DC COB LED strip, 4000K neutral white (HitLights, 16.4 ft reels)
Runs	3 ceiling runs in aluminum channels + frosted diffusers — two ~2,162mm over the tray, parallel to the X=520 / X=2270 drum-side red safelights, + one ~1,176mm running the IBC/plumbing corridor length (over the plumbing panel)
Power	~76W (4.2 W/ft × ~18 ft) → ~6.3A
Luminous output	426 lm/ft → ~7,670 lm total
Mounting	Surface aluminum channels (LED Profiles 981) on the ceiling
Dimmable	Yes (inline 12V PWM dimmer)
Circuit	G (10A fuse, 14 AWG) — 6.3A draw
Approximate cost	~$84 (2 reels) + ~$81 (3× 8 ft channel) + ~$15 connectors/dimmer

The three runs total ~5.5m of strip at 426 lm/ft → ~7,670 lumens across the ~14 m² floor area — approximately 548 lux, a solid workshop level for setup, maintenance, and cleaning. A 12V COB strip in an aluminum channel + diffuser gives an even, hot-spot-free ceiling wash (no discrete-fixture glare), runs cool, and is dimmable. At ~6.3A the Circuit-G feed is run in 14 AWG for margin and low voltage drop; the load still sits well inside the 10A fuse. True 12V-native (no inverter). Wired from Circuit G via the ceiling cable trunking.

6.3 Pull-Cord Switches

Two ceiling-mounted pull-cord switches are installed on the pinhole wall side of the container, accessible from the near walkway. Each switch controls one lighting circuit.

Parameter	Specification
Type	12V DC SPST pull-cord ceiling switch, 6A rated
Quantity	2
Position	Pinhole wall face, ceiling height
Switch 1	Circuit D — safelight (red). Cord labeled "RED"
Switch 2	Circuit G — white light. Cord labeled "WHITE"
Wire	Inline on respective circuit, between fuse block and load
Approximate cost	~$8 each, ~$16 total

The switches are positioned near the electrical panel, accessible from the near walkway. Pull-cord length is set so the cord hangs at approximately 1,500mm above the walkway deck — reachable without stretching.

7. Wiring Specification

7.1 Main Panel (Plywood Backboard + IP65 Enclosure)

An 18mm plywood backing panel (~700 × 2000mm) on the interior pinhole-wall face is the mounting surface every component fixes to. The DC-distribution terminals (fuse block + busbars + charge-line fuse) sit in a small IP65 weatherproof enclosure bolted to the plywood (its back panel is the plywood), sealing them against splash/dust from the water system; the MPPT, main disconnect, battery bank and inverter mount on the plywood outside it. It carries:

• Victron MPPT controller — on its own forward sub-panel, clear of the fuse-stack risers
• PV array disconnect — DC load-break isolator in the PV path (array → MPPT), wired in-line on the panel (NEC 690.13)
• Blue Sea 5026 12-circuit fuse block with busbars
• Battery positive and negative busbars, fed from the battery through a terminal-mount 200A MRBF fuse (on the battery + post, ≤180mm), a remote battery contactor (Blue Sea ML-RBS, tripped by either the exterior power-panel E-stop or an interior E-stop on the EP face, wired in parallel), and a main disconnect switch (Blue Sea m-Series 300A) — see §7.5
• MPPT charge-line fuse — a 60A ANL/MIDI fuse on the MPPT→battery lead at the busbar (§5.1)
• Interior E-stop — a red mushroom button (uxcell a19061100ux1510) on the EP face, paralleled with the exterior E-stop, so the contactor can also be tripped from inside the container (§7.5)
• Shore charger output terminals (with the 20A output fuse, §5.3)
• Circuit E inverter — Victron Phoenix 12/375 (GFCI version) mounted on the EP plywood panel (below the fuse gear, above the battery), with a short fused DC feed and its own DC disconnect (§7.6). Converts 12V DC → 120V AC for the evaporative cooler only.

Sheet 5 — Main Panel Layout Front elevation of the EP plywood panel (mirrors the 3D model), reach-optimized so every service item is reachable without a stool: bottom-to-top the battery pair (low, set-and-forget), the inverter, a grouped disconnect cluster at chest height (main disconnect · Circuit-C master pump switch · PV disconnect · interior E-stop), the Blue Sea 5026 fuse block + +/− busbars in the IP65 enclosure (also chest height), and the MPPT display at the top of the reachable stack. The internal feed one-line is Battery(+) → 200A MRBF → main disconnect → (+) busbar → fuse stack → circuits (and the PV-charge path through the MPPT). A fuse schedule lists each position's circuit, rating, wire gauge and load.

Sheet 2 — Container Wiring Layout Top-down floor plan (1:60 scale) showing all component positions, conduit routes, penetrations, drum panel, and connection points.

7.2 Circuit List

Circuit	Device	Fuse	Wire gauge	Run length
A	Ventilation fan — exhaust (far end wall, high)	5A	16 AWG	~2.5m
B	Ventilation fan — intake (panel-mounted, low)	5A	16 AWG	~8m + flex connector
C	Water pumps P-01–P-05 (5× Shurflo, master switch)	15A	14 AWG feed + 16 AWG branches	~5m feed (~8m to P-03)
D	Safelight (3× ceiling strips + drum)	5A	18 AWG	~15m (3 branches + drum)
E	Evaporative cooler inverter (12V DC input)	40A	10 AWG	~1m (battery → inverter)
E-AC	Inverter 120V AC out → panel cooler outlet	(GFCI at inverter)	14 AWG / SJOOW	~4m
F	Film plane actuators (optional)	20A	12 AWG	~6m
G	White LED strip ×3 (general lighting)	10A	14 AWG	~14m feed (3 runs ~5.5m lit, 6.3A)
—	Main battery fuse	200A	2/0 AWG	~0.5m (battery to busbar)
—	PV array disconnect (load-break isolator)	—	10 AWG	array → MPPT (at power panel)
—	MPPT charge-line fuse	60A	6 AWG	MPPT → battery (~0.5m)
—	E-stop control loop (exterior + interior, parallel)	—	2× 18 AWG	both → ML-RBS trip

7.3 Wiring Construction

Conduit: All DC wiring in gray corrugated conduit (Panduit or equivalent). Route in flat-profile cable trunking along the top corner rail of the container (40 × 25mm PVC trunking, UV-stabilized).

Connectors: - Interior connections: Anderson Powerpole 30A (red/black) — tool-free, industry standard for 12V DC - Exterior penetrations (fans, shore inlet): Deutsch DT series 2-pin weatherproof connectors — IP67 rated. (The cooler is 120V AC and terminates at the panel's GFCI-fed weatherproof outlet, not a DT connector — see Circuit E below and §7.6.) - Circuit B flex connector (panel-mounted intake fan): Fan B is mounted low on the swinging hinged panel. The wire run from the fuse block routes along the ceiling trunking to the fixed door frame, then crosses to the panel via a 1m coiled cable (16 AWG, 2-conductor, silicone-jacketed) with Deutsch DT 2-pin connectors at each end. The coiled cable must accommodate the ~56° transport swing about the pivot (with slack) without binding. Anchor the fixed end to the door frame top rail; anchor the panel end to the swinging frame near the pivot. The service loop hangs in the ceiling zone above and the wire drops down the panel to the low fan. - Circuit E (evaporative cooler, via inverter): The cooler is a 120V AC unit operating outside the container during sessions. The DC side is short: a fused 10 AWG feed (~1m) from the fuse block to the wall-mounted inverter, with its own DC disconnect. The AC side runs from the inverter's GFCI output along the ceiling trunking, down the pinhole wall to the external power panel, and terminates at the panel's weatherproof GFCI-fed NEMA 5-15R outlet (in-use cover). On the exterior, a 1.5m outdoor-rated SJOOW cord (NEMA 5-15P each end) connects the outlet to the cooler. The cord is unplugged and stowed inside for transport. Full grounding/GFCI design in §7.6. - Circuit C (water pumps P-01–P-05): The single 14 AWG Circuit-C feed is switched at a master pump switch on the Electrical Panel (EP) — one IP-rated manual cutoff for the whole pump circuit, upstream of everything — then runs along the ceiling trunking to a 12V DC distribution block (positive bus + shared negative bus) on the rear of the Corridor Plumbing Panel, which feeds each corridor pump directly via a short 16 AWG branch (~0.5–1m; 7.5A per pump). The four corridor pumps stack in a single column (bottom→top: ACC-01, P-01, P-02, P-05, P-03); P-04 (tray drain) taps the switched feed on the Pinhole-Wall filter skid. There are no per-pump switches — each Shurflo 2088 runs on its internal demand/pressure switch when its valves open, and the pumps are sequenced by opening the relevant valves (one at a time; simultaneous operation is not intended). The 15A circuit fuse protects the 14 AWG feed and covers a single pump (90W / 7.5A) with margin. The distribution block is in the wet zone — IP-rated, sealed, mounted above the spill line with drip loops (§7.5); the master switch is on the EP, clear of the wet zone.

Grounding: Bond the container steel body to the battery negative busbar using 4 AWG green/yellow wire at the main panel. Drive an 8-foot copper ground stake at the container foundation and connect to the main panel earth terminal. The inverter chassis, AC equipment-ground, and cooler ground bond to this same single point — see §7.6.

Labelling: Brady M210 wire labels at every terminal and every connector. Labels follow the circuit letter scheme (A–G) plus device description. Re-label after any wiring change.

7.4 Electrical Diagrams

Sheet 1 — System One-Line Diagram Complete power flow from solar panels through controller, battery bank, fuse block, and out to each circuit. Wire gauges, fuse ratings, and component models labeled.

Sheet 3 — Pinhole Wall Interior Elevation Interior elevation of the pinhole wall face, looking from inside the container. Shows equipment mounting heights, cable trunking at the ceiling corner rail, drop conduits to each device, pull-cord switch positions with cord lengths, and ceiling-mounted LED panel locations.

Sheet 4 — Plumbing-Panel Pump Power (Circuit C) Scale engineering elevation of the Circuit-C pump distribution on the corridor plumbing panel (matches the panel-layout elevation in the Plumbing Panel report §3.2): the switched 14 AWG / 15A feed (from the master pump switch on the EP — Sheet 5) → 12V distribution block → a 16 AWG curved-elbow branch to each of the four column pumps (bottom→top ACC-01, P-01, P-02, P-05, P-03; P-04 is fed on the Pinhole-Wall filter skid). No per-pump switches — the EP master switch is the single cutoff and each Shurflo runs on its internal pressure switch. See §7.3 (Circuit C) and the Plumbing Panel report §3.2.

Sheet 5 — Main Panel Layout Front elevation of the EP plywood panel (the 2D companion to the electrical 3D model's power_core), reach-optimized so every maintenance item clears no-stool reach (≤1.75 m): bottom-to-top the battery pair, the inverter, a grouped disconnect cluster at ~chest height (main disconnect · Circuit-C master pump switch · PV disconnect · interior E-stop), the color-coded A–G blade-fuse stack on the Blue Sea 5026 with the +/− busbars in the IP65 enclosure at chest height, and the MPPT display at the top of the reachable stack, with the internal feed one-line (Battery(+) → 200A MRBF → main disconnect → (+) busbar → fuse stack → circuits) and the PV-charge path. Includes a fuse schedule (position / circuit / rating / wire / load). See §7.1 and §7.3.

7.5 Circuit Protection & Electrical Safety

This is a 12 V DC (extra-low-voltage) system whose only 120 V AC element is the dedicated cooler inverter (Circuit E, §7.6); everywhere else the dominant electrical hazard is DC short-circuit / arc / fire, not shock — see the dedicated Electrical Safety Report for the full hazard assessment. The 120 V AC cooler branch introduces a genuine shock hazard that is contained by the isolation/GFCI/bonding design in §7.6. The following protective measures are part of the build:

• Emergency cut-off — two E-stops (inside + outside) — a magnetic-latch battery contactor (Blue Sea ML-RBS, 500 A) sits in the battery (+) feed, downstream of the MRBF fuse and upstream of the internal disconnect. It is tripped by either of two E-stop push-buttons wired in parallel: a red weatherproof IP66 button on the external power-panel face (kills the DC system from outside, without entry) and a red IP65 button on the EP face inside (so an operator already in the container kills it without going out to the panel). Pressing either opens the contactor and de-energizes the entire DC system. The magnetic latch holds the contactor open at zero standby current; reset is at the contactor's manual lever. A low-current 2 × 18 AWG control loop (both buttons in parallel) runs to the contactor, the exterior leg penetrating the pinhole wall through a sealed gland.
• Battery main disconnect switch (Blue Sea m-Series 300 A) between the contactor and the distribution busbar — a manual isolator for maintenance / service de-energization (the 200 A fuse is overcurrent protection, not a switch).
• PV array disconnect — a DC load-break isolator (50 A / 150 VDC) on the array→MPPT line at the power panel isolates the charge side (which the battery-side E-stops do not reach) for service or fault; MC4 connectors are not load-break rated (NEC 690.13).
• MPPT charge-line fuse — a 60 A ANL/MIDI fuse on the MPPT→battery lead (6 AWG) close to the battery protects the charge conductor, which the 200 A main fuse is too large to cover.
• Main fuse at the battery terminal — a terminal-mount MRBF fuse on the battery + post (≤180 mm, per ABYC E-11) protects the main cable along its whole length.
• Battery terminal covers over both posts/busbar; use insulated tools at the busbar.
• Sealed wet-zone connections — pump circuits in the IBC corridor / tray end use IP-rated connectors (Deutsch DT or adhesive-lined heat-shrink), tinned marine-grade wire, and dielectric grease on terminals exposed to chemistry vapor. Anderson Powerpole is reserved for dry interior circuits only.
• Chafe protection — grommets / cable glands at every steel-shell penetration; + and − conductors paired/sheathed.
• Wet-zone wiring elevated above the spill line, with drip loops and no connectors at the lowest points.
• Equipotential bonding — the IBC frame, walkways, and tray-adjacent metal are bonded to the battery-negative reference (6 AWG), in addition to the shell bond in §7.3, so any positive-to-metal fault clears cleanly through a fuse.

7.6 Circuit E — AC Isolation & Safety

Circuit E is the system's only 120 V AC branch: a dedicated 12 V→120 V pure-sine inverter (Victron Phoenix 12/375, GFCI version) powering one outdoor, water-wetted evaporative cooler beside a grounded steel box. That combination — lethal AC + a wet appliance + a conductive enclosure — is a real shock hazard, contained by five code-anchored rules:

1. Single neutral-ground bond (one source). The NEC permits exactly one neutral-to-ground bond in a system. The inverter is treated as a separately derived source: neutral is bonded to ground at the inverter only (the Phoenix GFCI version handles this internally) — no second bond downstream, which would either defeat the GFCI or cause nuisance trips. (NEC single-bond principle)
2. GFCI on the AC output — mandatory. An outdoor, wet-location 120 V receptacle requires GFCI protection (NEC 210.8). The recommended inverter has a built-in GFCI outlet; the panel's cooler outlet is fed from it, protecting the operator handling a wet cooler.
3. Equipotential bonding / effective fault path. The container shell, inverter chassis, cooler chassis, AC equipment-grounding conductor, and DC negative all tie to the single ground point (§7.3/§7.5). Any AC line-to-metal fault then has a low-impedance return that trips the GFCI/breaker instantly, so the steel shell can never become energized (NEC 250.110 / Art. 250 Part V).
4. DC-side protection + positive isolation. The inverter's 12 V feed is fused at the battery (40 A, 10 AWG, ~1 m) with a dedicated DC disconnect, so the entire AC subsystem is hard-isolated whenever the cooler is not running — which is most of the time. The external E-stop (§7.5) also kills it with everything else.
5. Galvanic isolation vs. bonding — by design. A transformer pure-sine inverter already isolates the AC live/neutral conductors from the 12 V battery side; rules 1–3 deliberately bond only the safety grounds to one point. Isolation (of the current-carrying conductors) and single-point bonding (of the grounds) are complementary, not in conflict.

Operationally: the cooler is plugged into the panel's in-use-covered GFCI outlet only during sessions; for transport the cord is unplugged and stowed and the inverter DC disconnect is opened. The Electrical Safety Report carries the full hazard assessment including this AC branch.

8. Parts List

All US/SoCal sources. Prices approximate as of 2026.

Item	Spec	Source	Est. cost
Solar panels	200W mono × 3	Renogy (renogy.com), Amazon	~$400
MPPT charge controller	Victron SmartSolar MPPT 100/50	altE Store (altestore.com)	~$200
LiFePO4 battery × 1 (standard)	100Ah 12V (Renogy Core RBT12100LFP-US)	offgridstores.com / renogy.com	$306
LiFePO4 battery — 2nd pack (optional, plug-in)	100Ah 12V, parallel onto the busbar (no rewiring) + its own MRBF terminal fuse	same	+$375
Shore backup charger	Victron Blue Smart IP65 12/15	altE Store	~$150
Fuse block	Blue Sea 5026 ST Blade 12-circuit	West Marine (Torrance CA) / Amazon	~$55
200A main fuse (terminal-mount)	Blue Sea MRBF on the battery + post (≤180mm, ABYC E-11)	Amazon	~$25
Battery main disconnect switch	Blue Sea m-Series 300A — manual isolator, contactor to busbar	West Marine (Torrance CA) / Amazon	~$40
Remote battery switch (contactor)	Blue Sea ML-RBS 500A magnetic-latch — in battery + feed, tripped by the external E-stop	West Marine (Torrance CA) / Amazon	~$150
External emergency cut-off (E-stop)	Red mushroom switch (uxcell a19061100ux1510) in a weatherproof control-station box (uxcell B07GN5P3NF, IP65, 78×71×64mm — ample for rain; upgrade to a gasketed IP66 box only if washdown-rated) + 2× 18 AWG control loop	Harfington / Amazon	~$21
Interior emergency cut-off (E-stop)	Red mushroom switch (uxcell a19061100ux1510), EP-face mount — paralleled to the exterior E-stop → ML-RBS trip	Harfington / Amazon	~$13
PV array disconnect	DC load-break isolator, 50A / 150VDC, panel-mount (array → MPPT; NEC 690.13)	AutomationDirect / Amazon	~$40
MPPT charge-line fuse	60A ANL/MIDI + holder on the MPPT→battery lead; 6 AWG charge conductor	Blue Sea / Amazon	~$15
Shore-charger output fuse	20A inline on the charger DC output lead	Amazon	~$5
Battery terminal covers (pair)	Insulating boots over + / − posts/busbar	Amazon	~$10
Sealed wet-zone connectors	Deutsch DT / adhesive-lined heat-shrink, pump circuits	Waytek Wire	~$25
Master pump switch (Circuit C)	1× IP67 sealed rocker/disconnect, 12V 16A — single cutoff for the whole pump circuit, mounted on the EP	Amazon / Waytek Wire	~$10
Pump distribution block	12V DC positive bus + negative bus (6-way), panel-mount on the rear of the Corridor Plumbing Panel, fed from the EP master switch	Blue Sea / Amazon	~$15
Dielectric grease	Marine-grade — chemistry-vapor terminal protection	Amazon	~$10
Tinned marine wire (wet-zone runs)	14/16 AWG tinned copper, ~25ft	Waytek Wire	~$30
Cable grommets / glands	Steel-shell penetrations (chafe protection)	McMaster-Carr	~$15
Equipotential bonding kit	6 AWG green/yellow + ring lugs — IBC frame / walkway / tray-metal to battery-negative	Amazon	~$20
Wiring kit	14/16/18 AWG, 50ft each color	Amazon / Waytek Wire (waytekwire.com)	~$80
Anderson Powerpole connectors	30A kit, 50 pairs	Powerwerx (powerwerx.com)	~$40
Deutsch DT connectors	DT 2-pin, 10 sets	Waytek Wire	~$30
Cable trunking	40 × 25mm PVC, 5m lengths × 4	Lowe's / McMaster-Carr	~$40
Corrugated conduit	Gray, 10mm ID, 10m	McMaster-Carr 7828K48	~$30
EP plywood backing panel	18mm, ~700×2000mm	Home Depot / Lumber yard	~$60
IP65 enclosure	~200×220×140mm (fuse block + busbars)	Polycase / Amazon	~$60
Brady label kit	M210 with wire label cartridge	McMaster-Carr / Amazon	~$80
NEMA 5-15R inlet	Weatherproof outlet box	Leviton / Amazon	~$25
Cooler inverter	Victron Phoenix 12/375, GFCI version (12V→120V pure-sine, Circuit E)	Victron / Amazon	~$210
Inverter DC protection	40A ANL fuse + holder + DC disconnect switch (inverter feed)	Blue Sea / Amazon	~$40
Panel AC outlet (Circuit E)	GFCI-fed weatherproof NEMA 5-15R + in-use (bubble) cover	Leviton / Amazon	~$25
Cooler power cord	1.5m outdoor SJOOW, NEMA 5-15P each end	Amazon	~$20
Copper ground stake	8ft × 5/8" diameter	Home Depot	~$20
4 AWG ground wire	Green/yellow, 3m	AutoZone / Amazon	~$15
Solar mount + PV cabling + power-panel	Ground tilt frame (30°), MC4 PV cable + bulkheads, flush-panel plate + gasket + bolts, 2/0 AWG battery cable	various	~$195
Evaporative cooler	Hessaire MC18M, 120V AC, 1,300 CFM (run low), 85W, 16 lb	Hessaire / Amazon	~$130
Shade canopy	80% shade cloth, 20 × 10ft	Amazon / Farm supply	~$80
Canopy frame	1.5" EMT conduit + fittings	Home Depot	~$120
Ventilation fans × 2	150×150×50mm 12V DC axial panel fan, ~150–200 CFM (dimension-audit correction; not the AC Infinity S6 inline)	Amazon	~$50
12V COB LED strip, 4000K, 16.4ft reel ×2 (L2712V-40D3-1630-U) + 6× LED Profiles 981 channel/diffuser (white + red) + connectors/PWM dimmers	white: 2× 2.16m tray + 1× 1.18m corridor (~7,670 lm / ~548 lux), 76W/6.3A, dimmable, true 12V	HitLights + LED Profiles	~$84 strip + ~$162 channel + ~$15
Red 12V COB LED strip, 5m reel (STN-B-BRED-O12A-08F5M-12V)	Circuit-D safelight — 40W/reel cut into 3 ceiling runs + drum (~40W/3.3A), COB 620nm, dimmable, cyanotype-safe, IP20	Super Bright LEDs	~$90
Pull-cord ceiling switch, 12V 6A SPST	Inline switch for lighting circuits D & G	Amazon / Lowe's	~$16 (×2)
Electrical system total			~$3,464
Shade canopy total			~$236
Cooling (cooler + inverter + DC protection + AC outlet + cord)			~$262
Systems grand total			~$3,962

Electrical system total is the standard 1-pack build and matches the consolidated Master Shopping List §6 (Solar & battery $1,335 + Distribution & wiring $989 = $2,324, the authoritative electrical BOM). The optional 2nd battery pack adds +$375 (its own MRBF fuse). It includes ~$410 of circuit-protection / wet-zone-sealing hardware added per the Electrical Safety Report §5 (interior + exterior emergency cut-offs + battery contactor, disconnect switch, terminal-mount fuse, PV array disconnect, MPPT charge-line + shore-charger fuses, sealed connectors, bonding, grommets), plus ~$25 of Circuit-C pump-control hardware (1 master pump switch + distribution block).

9. Maintenance

Interval	Task
Before each session	Check battery state of charge via Victron Connect app
Before each session	Verify all circuit fuses are intact on Blue Sea 5026 fuse block
Before each session	Test safelight (Circuit D) and white light (Circuit G) switches
Monthly	Inspect Anderson Powerpole connections for corrosion or looseness
Monthly	Check cable trunking clips and conduit routing for chafe
Monthly	Inspect Deutsch DT weatherproof connectors at fan penetrations; test the Circuit-E GFCI (cooler AC outlet) trip/reset
Every 6 months	Clean solar panel surfaces; check MC4 connector seals
Every 6 months	Inspect EPDM gasket on external power panel for compression set
Annually	Test battery BMS function (charge/discharge cycle under monitoring)
Annually	Inspect ground stake connection and measure earth resistance
Annually	Check pull-cord switch mechanisms for wear
Before transport	Disconnect evaporative cooler and stow per Equipment Layout §6.2
Before transport	Verify all circuit breakers/fuses are off except safelight standby

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10. Source References

1. Victron SmartSolar MPPT 100/50 — MPPT charge controller specifications.
2. Victron Blue Smart IP65 12/15 — Shore power backup charger specifications.
3. Blue Sea 5026 ST Blade Fuse Block — 12-circuit fuse block specifications.
4. Battle Born 100Ah LiFePO4 — LiFePO4 battery specifications.
5. Light Trap Selection Report — Revolving drum specification and commercial options evaluation.
6. Hinged Panel Report — Panel construction, pivot, latch, and swing-mechanism specification.
7. Water System Report — Pump circuits and water system electrical integration.
8. Equipment Layout Report — Component positions and shadow-free zone verification.