แปลงเป็น kVA (ออกแบบที่ p.f. 0.85 เพื่อความปลอดภัย — โหลดจริงเป็นอินเวอร์เตอร์ + LED เดินที่ ~0.95
ค่า kVA จริงจึงต่ำกว่า): 55 kW ÷ 0.85 ≈ 65 kVA บวกส่วนเผื่อโครงข่าย ~5 % →
≈ 70 kVA ความต้องการออกแบบสูงสุด ≈ ~100 A ต่อเฟส ที่ 400 V
ระบบที่แนะนำ: 3 เฟส 4 สาย เมน 160 A (≈ 111 kVA) — เพียงพอต่อความต้องการ ≈70 kVA พร้อมเผื่อเฟส 2
หาก กฟภ. กำหนดหม้อแปลงลูกค้า ให้ใช้ TR 100–160 kVA (22 kV / 400 V)ไม่ต้องติดตั้งชุดชดเชยเพาเวอร์แฟกเตอร์ — โหลดทั้งหมดเป็นอินเวอร์เตอร์และ LED ที่ ~0.95 p.f.
เผื่อช่องใน MDB สำหรับการขยายเฟส 2 (โฉนด 189415)
Status: preliminary engineering design — technical basis for subcontractor pricing. This document states the
design intent, loads and assumptions only; subcontractors propose their own pricing, equipment selections and
methods against it, alongside the PEA supply application.
It is not a construction issue. All final circuit sizing, protection settings, earthing design and the
single-line diagram must be reviewed, calculated and stamped by a licensed electrical engineer (สามัญวิศวกรไฟฟ้า, กว.)
registered with the Council of Engineers Thailand before construction and PEA energisation.
Electrical infrastructure for the Phase-1 SAFEBOX facility on Chanote 81903: a ~98.5 m (E–W) ×
60 m (N–S) walled compound, ~4,944 m² gross, holding 96 storage pods + 5 climate-controlled cube buildings (~410 rentable units),
a 9×5 m office/gatehouse, two 8 m sliding gates on the east entrance road, monument & banner signage,
site lighting and CCTV.
Design basis
Supply system: PEA low-voltage 400/230 V, 3-phase 4-wire, 50 Hz, TN-C-S / TT earthing (to be confirmed with PEA).
Standards: PEA regulations for LV service & metering; TIS / EIT (วสท.) 022013-xx Thai wiring code;
IEC 60364 principles; CPTED security-lighting practice.
Ambient: tropical, 40 °C design ambient in cable trenches/trays — cable de-rating applied in sizing.
Diversity applied per load group (see §3). All DBs specified with ≥25 % spare ways.
Assumption 1 — the existing street supply is 2-phase (the "Phase 2" line on the entrance road).
Engineering interpretation: the PEA low-voltage line on the entrance-road frontage currently carries only
2 phases of the network (a 2-phase street spur — common on sois), with the nearest connection point close to
the Entry Gate. The site requires a 3-phase 4-wire (400/230 V) service (aggregate A/C, dehumidifier,
gate-motor and lighting load — see §3), so PEA must extend/upgrade the frontage line from 2φ to 3φ (add the
third phase conductor, and confirm network/transformer capacity) as part of the service application.
Subcontractor + PEA to survey and confirm: the exact existing configuration (1φ or 2φ, conductor size, which pole),
the extension scope and lead time. This is a PEA network item — price the application/coordination and the intake
only, not the public-line works.
Assumption 2 — "MC11" (owner's note). Read as a distribution board / feed reference for the MediCube (MC2)
climate-cube cluster. In the architect working plan the MediCube (Double Medi MC2) sits in the SOUTH-EAST cube cluster
(with the Double Mini SafeCube and a Double Mega), so the MC11 feed is named DB-CUBES-SE in this plan.
The MID-EAST pair (the other Double Mega + the Double SafeCube SC2, beside the office) is fed by
DB-CUBES-E. If "MC11" is a specific meter, DB tag or pole number the owner already holds, please advise so
labels can be reconciled. The 12 M1cc climate pods sit together in ONE block at the east end of the central pod band (back-to-back
double row, immediately west of the Mega/Safe cube pair), so they are fed as
12 dedicated ways off DB-CUBES-E (≤20 m finals via pod-roof conduit) — each pod a dedicated circuit + socket
for its dehumidifier (the M1cc row is dehumidified, not air-conditioned).
See §3 (12 × 420 W = 5.04 kW) and the F2 run in §7. No separate pod board is needed.
Loads in scope
Climate control — all INVERTER type (interior LED + door sensors throughout): the cube buildings run
inverter A/C — SafeCube SC2 (3.5×12), Double Medi MC2 (4×12), 2× Double Mega (6×12), Double Mini SafeCube
(3×12); the 12 M1cc climate pods run inverter dehumidifiers (one per pod, each on its own powered circuit +
socket) rather than A/C. Inverter kit = soft-start (no inrush), part-load running, ~0.95 p.f.
Site lighting — standard, safe & secure (not floodlit):pod-roof extension masts staggered down the TWO DRIVE AISLES (A/B + C/D) only, cube wall-packs on the cube buildings, and the office soffit ring washing the gate area — zero freestanding poles, no perimeter masts, nothing outside the fence.
Two 8 m sliding gate motors + vehicle detection loops + access pedestals + intercom controller.
Entry gate = keypad/QR pedestal; exit gate = auto vehicle-loop open plus a manual push-button.
Pedestals sit on the driver's-right kerb (Thailand drives on the left, wheel on the right — see the gate note in §6).
Ambient (non-climate) storage pods are treated as unheated/unventilated; they carry only a single
LED + door contact each on the row-lighting circuits (negligible individual load). Only the climate buildings
carry A/C.
The existing PEA network on the entrance road (east boundary, P3→P4) near the Entry Gate is a 2-phase street
spur (exact configuration to be confirmed on survey). The design intent is a new 3-phase LV service off the
upgraded frontage line and locate the main
intake, meter and Main Distribution Board (MDB) at the Office/gatehouse (the natural attended point and shortest
feed to gates + cube cluster).
PEA application process (indicative)
Submit a 3-phase LV service request to PEA (Pattaya district office) with the estimated maximum demand
(§3 ≈ 70 kVA / ≈ 100 A per phase) and a single-line diagram signed by a licensed electrical engineer.
PEA determines service type. At ~70 kVA the site sits comfortably within a direct-metered LV service
(the real dehumidifier load — 12 × 420 W, not the earlier 12 × 1.2 kW allowance — pulled the demand down). Two
outcomes to price for:
(a) Direct LV metering — 3φ CT-metered service, PEA LV network drop to the meter at the office intake.
Preferred if PEA transformer capacity on the frontage is adequate.
(b) Customer transformer — if PEA requires it (typical when demand approaches/exceeds ~100 A per phase
or 250 kVA tariff bands), install a pad-mount/pole TR ≈ 100–160 kVA (22 kV/400 V) with HV metering.
Reserve space for a transformer pad near the office/entrance as a contingency.
Confirm tariff (small/medium general service) and whether TOU metering is beneficial (night-heavy A/C + lighting load).
Recommended supply size:3φ 4-wire, 160 A main (≈ 111 kVA capacity) to cover the ≈ 70 kVA estimated
maximum demand with generous headroom for the reserved Phase-2 expansion and EV provision. Main incomer: 4-pole
160 A MCCB with adjustable thermal + Type 2 SPD at the MDB. (A 100 A / ~69 kVA main would also serve the
current load, but 160 A keeps Phase-2 headroom.)
3. Maximum Demand Estimate / ประมาณการโหลดสูงสุด
Budget-level estimate. A/C sized from climate container floor area at ~120–150 W/m² cooling load
for insulated steel containers in Pattaya climate (≈ 400–500 BTU/h·m²), converted to electrical input at a typical
inverter split/ducted COP. All climate kit is INVERTER type (owner spec) — every cube A/C and every M1cc
dehumidifier. Inverter compressors soft-start (no large motor inrush), run at variable, mostly part load
and at high power factor (~0.95), so the diversity factors below are well justified, breakers/feeders don't
need motor-inrush headroom, and no power-factor correction is required (see §2).
Load group
Qty / basis
Connected (W)
Diversity
Demand (W)
Climate control — all INVERTER (inverter A/C on the cube buildings · inverter dehumidifiers on the M1cc pods) — DB-CUBES-E (mid-east, incl. the 12 M1cc dehumidifiers) · DB-CUBES-SE (south-east)
Double Mega cube ×2 (6×12 = 72 m² ea) — inverter A/C, 1 mid-east, 1 south-east
Spare / general small power (cleaning, tools, future)
—
4,000
0.50
2,000
Estimated maximum demand
—
≈ 85 kW
—
≈ 55 kW
Convert to kVA (design at p.f. 0.85 for safe-side sizing — the actual load is all inverter A/C +
inverter dehumidifiers + LED, which run ~0.95 p.f., so real kVA is lower and the estimate carries headroom):
55 kW ÷ 0.85 ≈ 65 kVA. Add ~5 % network/margin → ≈ 70 kVA design maximum demand ≈ ~100 A per phase
at 400 V. The efficient all-LED drive-aisle lighting (2.8 kW, vs a 22 kW conventional pole scheme) trims
the demand and keeps the site comfortably within a direct-LV service, though confirming supply type with PEA early
(§2) remains prudent.
Recommended supply: 3φ 4-wire, 160 A main incomer (≈ 111 kVA). If PEA mandates a customer transformer,
spec TR 100–160 kVA (22 kV / 400 V). No power-factor correction required — the whole load is inverter
A/C, inverter dehumidifiers and LED, all running ~0.95 p.f. Reserve MDB capacity for Phase-2 (chanote 189415) expansion.
4. Single-Line Diagram / แผนภาพเส้นเดี่ยว
Schematic (not to scale). Ratings indicative — to be confirmed by the licensed EE's calculations.
5. Site Electrical Layout / ผังไฟฟ้าในพื้นที่
Drawn LIVE from the current working plan (follows the shared current-plan pointer — today s64mg7ab, matched to the architect LAYOUT 2026.07.08 FINAL). Module footprints in light grey;
electrical routing runs in perimeter strips and along aisle edges — never through module footprints. North is up.
Scale ≈ 1 m : 6 px. Lighting masts are drawn ONLY along the two drive aisles (A/B + C/D) + the office — nothing at the perimeter, nothing outside the fence.
Incoming supply / meter MDB DB (CUBES-E / CUBES-SE / PODS-CC) Power feeder (NYY, trench) Lighting circuit Pod-roof LED mast (staggered, drives only) Light pool (coverage) Gate / signage CCTV camera (PoE) Vehicle detection loop Entry keypad/QR pedestal Exit push-button pedestal
Gate access control — pedestal side (Thailand: drive on the LEFT, steering wheel on the RIGHT).
Because the driver sits on the vehicle's right, every access pedestal is placed on the driver's-right kerb
so it is reached from the driver's window without leaving the car, set back ~1.2 m from the gate line.
GATE IN (entry): car heads west into the site → keypad / QR reader pedestal on the north kerb,
with a vehicle detection loop on the approach.
GATE OUT (exit): car heads east out → an in-ground vehicle loop auto-opens the gate, plus a
manual push-button pedestal on the south kerb as a backup / for anyone the loop misses.
Both loops are saw-cut into the approach lane and wired to the gate controller; free-exit loop + push-button are on
the DB-GATE/SIGNAGE circuit (see §3).
Design brief — light the TWO DRIVE AISLES (A/B + C/D) and the office area ONLY. The design target is that
customers feel secure without over-lighting the yard. Every luminaire is carried on a galvanized
extension mast bolted to a container/pod roof (as at the Bang Tao site) along the two drives — the containers
become the lighting grid, so there are no in-site concrete pole foundations and no cross-yard lighting trenching.
There are NO freestanding poles at all, NO perimeter masts and nothing outside the fence — not in the forecourt,
and not in the gate throats.
The gate and forecourt are lit off the Main Office building (a wall-pack on each of its 4 corners plus one flood
aimed down at the cars), and every pod mast has its base on the pod roof with the head cantilevered over the
drive — so nothing at all stands on the asphalt or blocks the drive-through.
Fixture, mounting height & the lumen method
Fixture classes (4000 K neutral, CRI≥70, IP65, full-cutoff to control glare & spill):
aisle & perimeter = 60 W LED flood ≈ 8,400 lm; cube / office-corner / gate wall-pack = 80 W ≈ 10,000 lm;
PIR security = 30 W. No high-output floodlights — this is a standard security level, not a floodlit yard.
Mounting height H = 5.3 m = 2.6 m pod roof + 2.7 m extension mast (recommended mast length).
Average lux (lumen method): E = (n · lumens · UF · MF) / A, where UF = utilisation factor for the target strip.
Staggered (criss-cross) spacing: one mast every ~15 m station along each aisle, alternating sides
(zigzag) → a light pool crosses the drive roughly every 15 m and ~30 m same-side. This is the sweet spot for a
standard-safe ~25–35 lux with even coverage and no dark pockets (U₀ min:avg ≥ 0.3), well below a "very bright"
50-lux floodlit spec but comfortably above the 10–15 lux where a yard starts to feel unsafe.
Street View check — the public entrance road is already lit. Google Street View along the east access road
(≈12.9430–12.9445 N, 100.9092–100.9098 E) shows existing PEA distribution poles carrying street-light luminaires
(cobra-head arms), overhead power lines, road drainage grates and a fire hydrant — a serviced public way, plus the M7
frontage is lit by motorway standards. Conclusion: no dedicated forecourt lighting poles are needed; the gate-post
wall-pack plus the office/canopy light the entrance zone. (Confirm lamp operation on a night visit; if a lamp is dark,
add one gate-side wall-pack.)
Photometric result by zone
Zone
Fixture
Mount H
Layout / spacing
UF
Calc. avg lux
Target
Drive aisles (2 main + M1 corridor)
60 W pod-mast
5.3 m
staggered, ~15 m station zigzag across the 7 m aisle
0.40
~33 lux
25–30
Cube surrounds (aprons)
80 W wall-pack
3.0 m wall
1 per cube bay
0.40
~55 lux
40+
Main Office + entrance (soffit downlights)
LED soffit downlight (~9 W ea)
~3.35 m soffit
continuous run under the roof overhang, ALL around the office (~1.6 m spacing) — no wall floods, no pole
0.45
~50 lux
40–60
Forecourt / entrance road
existing PEA street lights
—
public road (Street View)
—
lit (existing)
—
Back-of-house / dark corners
(optional later) 30 W PIR flood
—
motion-triggered, add-on if wanted
—
—
—
Uniformity & glare: the staggered aisle layout targets U₀ (min:avg) ≥ 0.3; aim angle held
≤ 70° from vertical with full-cutoff optics to limit glare and spill onto the M7 frontage and neighbours. ~25–35 lux
with good uniformity still supports CPTED security and usable CCTV night images without floodlighting the yard.
Fixture schedule & connected load
Zone
Fixture / mount
W ea
Qty
Total W
Drive aisles A/B + C/D (staggered pod-masts, ~15 m zigzag)
60 W LED flood on pod-roof extension mast
60
12
720
Cube surrounds
80 W LED wall-pack
80
8
640
Main Office — soffit downlights under the roof overhang, all around
LED soffit downlight (~9 W)
9
~22
~200
Signage (monument 2 faces + banners)
sign-lighting LED
—
lot
700
Office / canopy / kiosk
downlight + canopy + wall-pack
—
lot
500
Total connected lighting load
≈ 2.8 kW
Total masts: 12 — 6 per drive, staggered ~15 m, drives A/B + C/D only, all with the
base on the pod roof and the head cantilevered over the drive — none stand on the asphalt, none at the perimeter,
none outside the fence; plus 9 wall-packs (8 cube + 1 gate flood), the office soffit ring, and
ZERO freestanding poles. Fixture counts are budget-level, to be finalised by an isolux calc; the lumen-method
averages above verify a standard-safe security level on the drives. Back-of-house PIR floods can be added later on the
same circuits if night CCTV wants more fill.
Controls
Dusk-to-dawn photocell master enable + astronomical time-clock/contactor zones:
Zone A perimeter+gates (dusk→dawn full), Zone B aisles (dusk→dawn, dim to 50 % after 23:00 optional),
Zone C signage (dusk→set curfew, e.g. 24:00), Zone D pod-row + back-of-house on PIR motion with a low base level.
All external luminaires IP65, surge-protected drivers, individually fused at the pole base / mast bracket.
Gate + apron stay at a clear, secure level (~50–60 lux) on vehicle detection even if aisles are dimmed.
Voltage-drop checked on the longest runs — the site is ~98.5 m E–W, so the far west end of the drives (lighting + CCTV) is ~85–90 m from the MDB at the office. Feeders upsized to hold total V-drop ≤ 4 % (≈ 9 V on 230 V finals /
16 V on 400 V feeders) per TIS. Cables NYY (LV power) / CV (XLPE) for the main feeder; direct-buried in
HDPE conduit in shared trenches, 0.6–0.8 m deep, with warning tape + spare draw-ropes.
Run
From → To
Approx length
Cable
Protection
Method
Service main
PEA meter → MDB (Office)
10–20 m
CV 4×50 + 25 mm²
160 A 4P
HDPE Ø63 trench
F1 Cubes-SE
MDB → DB-CUBES-SE ("MC11": Mega + MC2 + MiniSC2, south-east)
DB-CUBES-E → dehumidifier socket, 1 per pod (420 W = 1.9 A), surface conduit on the pod roofs
≤ 20 m ea
NYY 3×2.5 mm²
10 A + RCBO 30 mA
surface conduit on pod row
Cube A/C final (typ.)
DB-CUBES → inverter condenser (soft-start, no inrush)
≤ 12 m
NYY 3×4 mm²
20–25 A RCBO
tray/conduit on wall
CCTV (PoE)
NVR/switch → cameras
≤ 90 m each
Cat6 outdoor / fibre if >90 m
PoE+ (30 W)
HDPE Ø25 w/ power trenches
Gate loops
controller → in-ground loop
—
loop wire in saw-cut
detector card
sealed slot in road
Trench strategy: a main perimeter trench carries the lighting ring + CCTV; a spur trench crosses
to the cube cluster carrying F1/F2; separate LV power and ELV (CCTV/data) by ≥ 150 mm or use a divided duct bank.
Provide draw-pits at each direction change and at every pole base.
Critical — every unit is a steel container (a conductive box). All container bodies, cube buildings, metal
fence sections, gate rails/motors, poles and the office frame must be bonded to the main earth terminal to
prevent a fault making any steel surface live. This is the single most important safety item on the site.
Main earth electrode: earth-rod array / ground grid at the MDB, target ≤ 5 Ω (≤ 1 Ω if HV
transformer installed). Test and record.
Equipotential bonding: run a bare copper earth conductor (min 25 mm² Cu) in the perimeter and aisle
trenches; bond each container row, cube building, pole, gate and fence panel to it with clamps.
RCBO protection: 30 mA RCBO on all socket, external, wet-area and sign/pole final circuits; 100–300 mA
time-delayed selective RCD on feeders as required for discrimination.
Surge protection: Type 2 SPD at MDB; Type 3 at the office ELV/CCTV rack and at signage; SPD on gate
controller supply.
Lightning protection (LPS): assess per TIS/IEC 62305 risk. The tall monument sign, gate poles and the
pod-mounted extension masts are exposed metal — bond every mast to its container roof and into the site earth
grid; recommend air-terminals/down-conductors on the monument. A licensed engineer to confirm whether a full
structural LPS is required or whether bonding + SPD suffices for the low-rise containers.
9. Compliance Notes / ข้อกำหนดและมาตรฐาน
PEA (การไฟฟ้าส่วนภูมิภาค): service request, meter type and network capacity confirmation at Pattaya
district office; comply with PEA LV service & metering regulations; PEA inspection before energisation.
Thai wiring standard: design and install to the EIT / วสท. wiring standard (มาตรฐานการติดตั้งทางไฟฟ้าสำหรับประเทศไทย)
and relevant TIS product standards; cable selection, V-drop and protection per that code.
Licensed sign-off: single-line diagram, load schedule and earthing design to be calculated, drawn and
stamped by a licensed electrical engineer (กว.); large-building/commercial work may require a
สามัญวิศวกร level depending on connected load.
Signage: illuminated monument & banners subject to signboard tax and local permit — coordinate the
electrical feed with the approved sign structure and setback (see the project fence & signage plan).
Testing: insulation resistance, earth-loop impedance, RCD trip tests, earth-electrode resistance,
polarity — all recorded in a commissioning report handed to the owner.
10. Open Questions — Owner / PEA / ประเด็นที่ต้องยืนยัน
2-phase street line: the frontage line near the entrance is reported as 2-phase.
PEA to state the 2φ → 3φ extension scope, cost responsibility and lead time for the frontage line.
"MC11" — confirm whether this is the MediCube DB in the south-east cube cluster (our DB-CUBES-SE) or a
specific existing meter/pole/board tag we should match.
Existing connection point: survey the frontage — which pole, conductor size/type, 1φ or 2φ, any existing
meter on the land — and whether a new service drop or an in-place upgrade is required.
Direct LV vs transformer: does PEA's frontage network have capacity for a ~70 kVA direct LV service, or
will a customer transformer be required? (At ~70 kVA a direct LV service is the more likely outcome — subcontractor to confirm with PEA.)
Climate kit selection: all inverter confirmed. Dehumidifiers confirmed: 30 L/day, 420 W @ 220 V
(0.72 kg/h, tank 7 L, 5–125 m² coverage) — the load table now uses the real 420 W, not the earlier 1.2 kW
allowance, which cut the site demand to ~70 kVA. Still confirm cube A/C setpoint/humidity and whether ducted
or multi-split to finalise cube A/C kW.
Operating hours & night dimming: is the site gate-access 24/7? Confirm whether aisles may dim after
hours (affects lighting energy, not the fixture count).
EV charging: provision only (as assumed), or install a live charger now?
Phase-2 (chanote 189415): reserve MDB spare ways / trench stubs toward the south now? (Recommended.)