Wiring Plan — Juliet Coffee Water System Control Panel

Field	Detail
Document Number	RO-SPEC-001 / WIRE-001
Revision	Rev D — adds the forced-air cooling system (4× Noctua NF-A12x25 fans + Mean Well DDR-15G-12 24→12 V converter + PT100 enclosure RTD, two-stage PLC control on the second P2-08TRS) per BOM Rev N. New §14 covers enclosure cutouts, fan/filter install, 12 V power architecture, RTD termination, and the new relay assignments; §2 thermal note rewritten (passive → active forced air); §3.3 24 V load budget updated; §4 / §7 / §9 tables updated for the new TT-200 RTD channel and the two new relay points.
Anchored to	System overview §5 (controls), §5.7 (enclosure cooling), §6 (electrical); BOM Rev N
Scope	Internal wiring of the control enclosure: 240 VAC service in → branch breakers → VFDs / control bus → PLC, HMI, I/O, field devices. Field wiring stops at the panel terminal strip; piping, sensor placement, and motor mechanical install are covered in the system overview.

⚠ All work shall be performed by a licensed electrician in accordance with NEC Article 430, NFPA 79, and UL 508A. This document is a build/wiring intent — it is not a substitute for the as-built panel schematic that the panel shop/electrician will produce and stamp.

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1. Conventions

1.1 Wire colour code (UL 508A §66)

Function	Insulation colour
Ungrounded AC line (240 VAC, 120 VAC)	Black (L1) / Red (L2)
Grounded AC neutral	White
AC control circuit ≤ 120 V derived inside panel	Red
DC control positive (+24 VDC)	Blue
DC control common (0 VDC)	Blue with white tracer
Equipment grounding conductor	Green or Green / Yellow
Foreign voltage — energised with main disconnect OFF	Orange (none expected in this build)

1.2 Wire gauge & terminations

Circuit class	Min gauge	Termination
240 VAC branch to VFDs (CB-1)	10 AWG THHN	DN-T12-A feed-through (24-12 AWG rated)
240 VAC branch to VFDs (CB-2, CB-3)	14 AWG THHN	DN-T12-A
120 VAC control branch (CB-4)	12 AWG THHN	DN-T12-A
VFD output to motor	VFDC-16-4B-1 (16 AWG, 4-cond, shielded XLPE/TPE)	Drive lugs at VFD; motor box at the load
24 VDC field power	16–18 AWG MTW	DN-T12-A
PLC discrete I/O field wiring	18 AWG MTW	Field side: DN-T12-A. Module side: P2-RTB screw terminals.
PLC analog I/O (4–20 mA, 0–10 V, 0.5–4.5 V)	18 AWG twisted-pair shielded (e.g. Belden 8761 or equivalent) — shield grounded at panel end only	DN-T12-A on field side; P2-RTB on module side
RTD (3-wire)	22 AWG 3-conductor shielded	DN-T12-A; P2-RTB
RS-485 Modbus RTU	Q8302-1 (24 AWG, 1 twisted pair, shielded) — daisy-chain, 120 Ω terminations both ends	Drive RS-485 screw terminals; PLC RS-485 port
Equipment grounding	12 AWG green (control), 10 AWG green (VFD)	DN-G10-10 grounding terminal blocks bonded to DIN rail and panel ground bus

1.3 Tag conventions

• Terminal numbers follow the convention <rail>-<block> — e.g. TB1-12 is rail TB1, block 12. Each I/O point gets exactly one panel-side terminal block.
• Wire labels are heat-shrink type, marked at both ends with the source-destination pair (e.g. P101-VFD-101 U).
• Device tags match the system overview (P-101, VFD-101, FT-101, SV-RECIRC, etc.).

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2. Panel Layout

The enclosure is a Hoffman (nVent) CSD362410 — Concept Single-Door Wall-Mount (why I chose this Hoffman PLC enclosure), 36" H × 24" W × 10" D, gray steel, NEMA Type 4 / 12 / 13 (IP66), UL 508A Listed (File E61997), with the matching CP3624G conductive (galvanized) sub-panel (32.13" × 20.13" mounting area).

The shell carries an explicit UL 508A listing on the nameplate, so the panel-shop / electrician signs the 508A label against File E61997 rather than re-evaluating the enclosure.

After subtracting 2.25" wire duct on each side, this leaves ≈ 20" of usable horizontal sub-panel.

Final layout still hits the ≥ 25 % spare DIN rail intent of UL 508A §28. Verify during the panel-build dry-fit before bonding rails to the backplate.

┌───────────────────────────────────────────────────────────────────────────┐
│ ZONE A — Service & Branch Protection (top, two horizontal rails)          │
│  Rail A1 (upper):                                                         │
│   Main disconnect (Socomec SIRCO M, side-shaft to door handle) ─ L1/L2/N/G│
│   CB-1  (GMCBU-2C-20, 20 A 2P)  →  VFD-101                                │
│   CB-2  (GMCBU-2C-15, 15 A 2P)  →  VFD-102                                │
│   CB-3  (GMCBU-2C-15, 15 A 2P)  →  VFD-103                                │
│   CB-4  (GMCBU-1C-15, 15 A 1P)  →  120 VAC controls / brains              │
│   CB-5  (GMCBU-1C-15, 15 A 1P)  →  120 VAC metering pump receptacles      │
│   CB-6  (GMCBU-1C-15, 15 A 1P)  →  120 VAC UV receptacle / contactor      │
│  Rail A2 (lower, immediately below A1):                                   │
│   L1 KN-T8BLK feed-through stack (1 in + 6 out) + KN-10J8 jumper          │
│   L2 KN-T8RED feed-through stack (1 in + 3 out) + KN-4J8 jumper           │
│   NA-414-1 isolated neutral bus (CB-4/5/6 returns)                        │
│   KN-ECT6GRY end covers on both stacks                                    │
├───────────────────────────────────────────────────────────────────────────┤
│ ZONE B — Drives + Line Reactors                                           │
│  Drives row (3 across, 50 mm / 2" gap between drives per GS21 manual):    │
│   VFD-101 (GS21-21P0)  ─  VFD-102 (GS21-20P5)  ─  VFD-103 (GS21-20P5)     │
│  Line reactors (mounted ABOVE or BELOW drives, NOT beside — width-bound): │
│   LR2-21P0-1PH-A   (1 HP, into VFD-101)                                   │
│   LR2-20P5-1PH × 2 (½ HP, into VFD-102 / VFD-103)                         │
├───────────────────────────────────────────────────────────────────────────┤
│ ZONE C — PLC & Power                                                      │
│   P2-01AC  ─  P2-11B base  ─  P2-550 CPU       (base ≈ 11" wide)          │
│     Slot 1: P2-16ND3-1   (16-pt DC IN)                                    │
│     Slot 2: P2-08TRS #1  (8-pt relay OUT)                                 │
│     Slot 3: P2-08TRS #2  (8-pt relay OUT)                                 │
│     Slot 4: P2-08AD-2    (8-ch analog IN)                                 │
│     Slot 5: P2-06RTD     (6-ch RTD IN)                                    │
│     Slots 6–10: SPARE (reserved for future P2-08AD-2 expansion first)     │
│   Mean Well NDR-120-24   (24 VDC field PSU; mounts beside the P2-11B)     │
│   ZL-RLS4-24 metering-pump relay module                                   │
│   SE3-SW5U Ethernet switch                                                │
├───────────────────────────────────────────────────────────────────────────┤
│ ZONE D — Field Terminals (bottom; more rails of fewer blocks each)        │
│   TB1: 240 VAC motor leads to drives (Zone B → motor)                     │
│   TB2: 120 VAC loads (controls, UV, metering pumps)                       │
│   TB3: 24 VDC field distribution                                          │
│   TB4: Discrete inputs                                                    │
│   TB5: Relay output loads                                                 │
│   TB6: Analog inputs (shielded TP)                                        │
│   TB7: RTD                                                                │
│   TB8: RS-485 Modbus                                                      │
│   GND: DN-G10-10 grounding bar                                            │
└───────────────────────────────────────────────────────────────────────────┘

Door layout (CSD362410 single door, ≈ 24" wide):

• CM5-T10W HMI mounts top-centre, cutout 9.92" W × 7.13" H per the C-more CM5 datasheet.
• Four GCX3370-22 22 mm selector switches mount in a single horizontal row immediately below the HMI (HOA selectors for MP-101 / MP-102 / MP-103 / UV).
• Socomec SIRCO M rotary handle (14741111) mounts on the side of the door (right-side external operator), driven through the side-shaft (14070515) to the in-panel disconnect on Rail A1.

DIN rail: all rails are 35 mm slotted plated steel — DN-R35S1 cut to length per zone. Each rail is bonded to the CP3624G conductive sub-panel with a green 12 AWG jumper through a DN-G10-10 block; the sub-panel itself is bonded to the panel ground bus (see §13). Each terminal-block group is bookended with DN-EB35MN end brackets and capped with a DN-EC1210MN end cover.

The HMI (CM5-T10W) connects to the in-panel components by a service loop through a flexible cable carrier so the door can swing without cable strain.

Thermal note: wall surface area at 36 × 24 × 10 is ~16 % less than the original 36 × 30 × 10 basis. With the VFDs at load, estimated panel losses run ~200–300 W (drives dominate; line-reactor and PSU standby contribute the rest). Passive dissipation off the 18.7 ft² steel shell is not adequate at typical San Diego summer indoor ambient (90–100 °F / 32–38 °C) for that load — and the +40 °C / 104 °F operating limit on the Gladiator miniature breakers is the binding constraint, lower than every other component in the panel. Forced-air cooling is therefore installed (4× Noctua NF-A12x25 fans, 2 intake low + 2 exhaust high, with PLC two-stage on/off control on TT-200 enclosure RTD). Full install detail: §14 Enclosure Cooling System. After punching the four 4″ fan cutouts, the enclosure rating drops from NEMA 4 / 12 / 13 to ≈ NEMA 12 / IP54 — fine for the indoor coffee-shop install, no longer rated for hose-down or wet locations.

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3. Power Distribution

3.1 Service entrance

• Supply: 240 VAC ± 10 %, 1-phase, 60 Hz, 3-wire + ground (split-phase L1 / L2 / N / G), nominal 30 A branch from the host facility breaker panel.
• Disconnect: Socomec SIRCO M series rotary disconnect switch, 3-pole, 600 VAC, 32 A, 65 kA SCCR, UL 508 rated, with 150 mm 5 × 5 mm shaft and red/yellow lockable external handle. The third pole is spare in this split-phase build unless the panel shop elects to switch neutral; neutral remains isolated from ground either way.
• Equipment grounding: dedicated green 10 AWG conductor from the host facility ground bar to the panel ground bus. The panel neutral and ground are bonded only at the host facility service entrance, never inside this panel.

3.2 Branch circuits (per system overview §6)

Tag	Breaker (AutomationDirect)	Pole / Trip	Feeds	Wire (panel side)
CB-1	GMCBU-2C-20	2P / 20 A	LR2-21P0-1PH-A → VFD-101	10 AWG black/red
CB-2	GMCBU-2C-15	2P / 15 A	LR2-20P5-1PH → VFD-102	14 AWG black/red
CB-3	GMCBU-2C-15	2P / 15 A	LR2-20P5-1PH → VFD-103	14 AWG black/red
CB-4	GMCBU-1C-15	1P / 15 A	Controls / brains: P2-01AC PLC PSU, NDR-120-24 24 VDC PSU, HMI branch, control auxiliaries	14 AWG black + white N
CB-5	GMCBU-1C-15	1P / 15 A	Metering pump branch: MP-101 / MP-102 / MP-103 receptacles or hardwired feeds	14 AWG black + white N
CB-6	GMCBU-1C-15	1P / 15 A	UV branch: Pulsar PUV-200-20 GFCI receptacle / upstream contactor	14 AWG black + white N

CB-4, CB-5, and CB-6 are fed from L1 + N (120 V leg). Each single-pole breaker interrupts L1 only; neutrals return to an isolated neutral bus sized for the branch count and current.

Neutral bus sizing: use a UL-recognized isolated neutral bus or terminal-block assembly rated ≥ 30 A and sized for at least 12 neutral landings. Minimum active neutral count is CB-4 feed/loads, CB-5 feed/three pump receptacles, CB-6 UV receptacle, plus spare/service points. A 12-position bar is the practical minimum; the procured Penn-Union NA-414-1 (22 openings / 20 circuits) is generously sized for the 36" × 24" enclosure with room for future service loops and added auxiliaries.

3.3 24 VDC field power — Mean Well NDR-120-24

• Input: 120 VAC from CB-4 controls / brains branch, fused at 2 A on the line side (use a fused DN-T12-A or in-line midget fuse holder).
• Output: 24 VDC, 5 A continuous → DIN-rail distribution at TB3.
• A separate 2 A breaker / fused holder on the +24 V output protects downstream branches.
• Field load budget (estimate, per system overview §3 / §4):

Load	Qty	Current draw (A)
Pressure transmitters PT-101…PT-104	4	~0.04 (ratiometric, < 10 mA each)
Conductivity sensors CT-101…CT-103	3	~0.10 (loop-powered 4–20 mA)
LT-102 level transmitter	1	~0.025
Flow meters FT-101…FT-103 (pulse, 5–24 V)	3	~0.15
Level switches LSH-101 / LSL-101 / FS-101	3	~0.01
Solenoid valves SV-RECIRC / SV-ICE / SV-TREAT (24 VDC coils)	3	up to 1.5 (~0.5 each, holding)
Ball valve actuator (24 VDC, spring-return)	1	up to 0.5 (running), < 0.05 holding
HMI CM5-T10W	1	~1.0 (per datasheet, 12–24 VDC input)
DDR-15G-12 input (enclosure cooling fans — see §14)	1	~0.4 (4 fans × ~1.7 W ÷ ~85 % efficiency ÷ 24 V; worst case both stages on)
Subtotal (worst case all energised)		≈ 3.8 A

The NDR-120-24 (5 A) carries this with > 20 % headroom. The DDR-15G-12 sees no inrush worth flagging — its 24 V input is always energised whenever the panel is on; it's the 12 V output that is switched on/off by the P2-08TRS relays, not the converter's mains-side input.

3.4 P2-01AC (PLC backplane PSU)

• Mounted at the left end of the P2-11B base (no slot consumed).
• Fed directly from the CB-4 controls / brains branch through its own DN-T12-A pair (L1, N) and a green 12 AWG ground bonded to the panel ground bus.
• Powers the P2-550 CPU and all five I/O modules through the backplane. No external 24 VDC required for the discrete and relay modules. The P2-08AD-2 analog input module requires a separate 24 VDC supply — fed from the NDR-120-24 (see §6).

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4. PLC Backplane — Slot Assignments

Reproduced from system overview §5.2, for cross-reference:

Slot	Module	Field role
CPU	P2-550	Main CPU
1	P2-16ND3-1 (16-pt 24 VDC IN)	Discrete inputs (level switches, flow pulse, VFD status, ice demand)
2	P2-08TRS (8-pt Form-C relay)	Loads bank 1 (ball valve, UV, 3× metering pumps, 3× VFD run/stop)
3	P2-08TRS (8-pt Form-C relay)	Loads bank 2 (SV-RECIRC, SV-ICE, SV-TREAT, FAN stage 1, FAN stage 2)
4	P2-08AD-2 (8-ch analog IN)	Pressures + conductivities + LT-102
5	P2-06RTD	Temperature (ch 1: TT-101 process water; ch 2: TT-200 enclosure air)
6–10	spare	First reserved slot is a future second P2-08AD-2 (analog rail is full)

Each populated module gets one P2-RTB 18-pin removable terminal block for field wiring. Stock four spares.

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5. Discrete Input Wiring — P2-16ND3-1 (Slot 1)

Configured sinking (24 VDC source provided by panel; the field device sinks current to 0 V on closure). Terminal numbering follows the AutomationDirect P2-16ND3-1 RTB pinout: two isolated commons (C1, C2), eight inputs per common (X1–X8 on C1, X9–X16 on C2).

Both commons (C1, C2) are jumpered to the 0 VDC bus (DN-24J2Y push-in jumper across the common terminals on the field side). +24 VDC is delivered to each field device through a dedicated DN-T12-A; the device's dry contact closes to return that 24 V to the input pin.

Input	Tag	Source device	Function	Wiring
X1	LSH-101	T-101 high-level float (N.O.)	Stop P-101 RO production at high tank	+24 V → switch → input pin
X2	LSL-101	T-101 low-level float (N.O.)	Stop P-102 to protect pump; alarm	+24 V → switch → input pin
X3	FT-101	Feed flow pulse	Recovery calc	Pulse output (5–24 VDC) → input
X4	FT-102	Permeate flow pulse	Recovery calc	Pulse output → input
X5	FT-103	Distribution flow pulse	POU monitoring	Pulse output → input
X6	VFD-101 RUN/FLT	GS21-21P0 status (DO1 → MO/MCM)	Drive running OK	Drive sink → input
X7	VFD-102 RUN/FLT	GS21-20P5 status	Drive running OK	Drive sink → input
X8	VFD-103 RUN/FLT	GS21-20P5 status	Drive running OK	Drive sink → input
X9	FS-101	Ice machine demand switch	Triggers SV-ICE	+24 V → switch → input
X10–X16	spare	—	—	—

Note on T-102 level: the system overview specifies LT-102 (4–20 mA continuous transmitter on T-102) wired to the analog rail (P2-08AD-2 ch 8), not to discrete inputs.

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6. Analog Input Wiring — P2-08AD-2 (Slot 4)

The B-P208AD2 supports both 0–10 VDC and 0–20 mA per channel, configurable in software per channel. The module requires external 24 VDC wired to its +24 V and 0 V terminals on the RTB — fed from the NDR-120-24 / TB3 bus.

All eight channels are populated. Shielded twisted pair from the field; shield drain wire grounded at the panel end only (DN-G10-10).

Ch	Tag	Device	Range	Type	Wiring
1	PT-101	Pressure — feed inlet	0–300 psi	0.5–4.5 VDC ratiometric	+V (loop +24 V), Sig → ch+, 0 V → ch−
2	PT-102	Pressure — RO high-side	0–300 psi	0.5–4.5 VDC	as above
3	PT-103	Pressure — permeate	0–300 psi	0.5–4.5 VDC	as above
4	PT-104	Pressure — distribution header	0–300 psi	0.5–4.5 VDC	as above
5	CT-101	Conductivity — feed (Hanna HI7635)	0–3999 µS/cm	4–20 mA	2-wire loop powered (+24 V → tx +, tx − → ch+, ch− → 0 V)
6	CT-102	Conductivity — permeate (Levtech HMCCS)	0–1000 µS/cm	4–20 mA	as above
7	CT-103	Conductivity — T-102 inlet (Levtech HMCCS)	0–1000 µS/cm	4–20 mA	as above
8	LT-102	Level — T-102 (continuous)	4–20 mA = 0–100 %	4–20 mA	as above

The four 0.5–4.5 V pressure sensors are configured as 0–10 V channels in software; the four 4–20 mA loops are configured as current channels. Channel-by-channel mode selection avoids needing a different module.

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7. RTD Input Wiring — P2-06RTD (Slot 5)

Temperature input only. The included P2-RTB takes 3- or 4-wire RTDs; this build uses 3-wire Pt100 or Pt1000 per the spec.

Ch	Tag	Device	Wiring
1	TT-101	Pt100 / Pt1000 — feed/permeate	EX+ (excitation), Sense, RTN — 3-wire, shield grounded at panel
2	TT-200	Pt100 — enclosure air (waterproof 1 m probe)	EX+, Sense, RTN — 3-wire. Probe sits inside the enclosure above the drives (worst-case warm zone). Run the 1 m lead through a strain relief at the probe's mount point; land all three conductors on the P2-RTB; configure ch 2 as Pt100 in the IDE Hardware Configuration. See §14.4 for placement guidance.
3–6	spare	—	—

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8. Relay Output Wiring — P2-08TRS #1 (Slot 2)

The P2-08TRS provides 6 × Form A and 2 × Form C dry-contact outputs, each with isolated common, rated 4 A / point at 6–24 VDC or 6–120 VAC.

This module switches 120 VAC and 24 VDC loads. Use its dry-contact relays to make/break the hot leg of a separately fused load circuit — do not source power through the module common terminals.

Output	Tag	Load	Voltage	Wiring
Y1	BV-101	Automated ball valve actuator	24 VDC	+24 V → Y1.NO → actuator + ; actuator − → 0 V
Y2	UV-101	CWC07-00-40V18 UV contactor	120 VAC coil	The Pulsar is plug-connected to a CB-6-fed 120 VAC GFCI receptacle through the Rev K BOM contactor: WEG / AutomationDirect CWC07-00-40V18, 7 A, 4 N.O. power poles, 120 VAC coil. Y2 switches the upstream contactor coil so the PLC can de-energise UV power on hard-alarm. (Pulsar's own controller continues to manage lamp life and audible alarms while powered.)
Y3	MP-101 ENABLE	Magnesium sulfate dosing pump (MgSO₄)	dry contact	Y3.NO lands on the DDC external stop / enable input. Pump power remains on CB-5; the PLC enables dosing without cycling pump mains power.
Y4	MP-102 ENABLE	Calcium chloride dosing pump (CaCl₂)	dry contact	as above
Y5	MP-103 ENABLE	Sodium bicarbonate dosing pump (NaHCO₃)	dry contact	as above
Y6	VFD-101 RUN	GS21-21P0 run command	24 VDC dry	Y6.NO → drive MI1 ; drive DCM → 0 V (sink configuration). RUN is a maintained closure; drive is configured for 2-wire start.
Y7	VFD-102 RUN	GS21-20P5 run command	24 VDC dry	as above
Y8	VFD-103 RUN	GS21-20P5 run command	24 VDC dry	as above

Per-load fusing: Y2's UV contactor coil should be protected by a small fuse or fused terminal block sized to the coil. The three metering pumps are on their own CB-5 branch; individual pump fuses are optional rather than mandatory if each receptacle / hardwired feed uses code-compliant 14 AWG branch wiring. Add per-pump fused terminal blocks only if you want fault isolation and service clarity at the cost of extra parts and wiring.

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9. Relay Output Wiring — P2-08TRS #2 (Slot 3)

Output	Tag	Load	Voltage	Wiring
Y1	SV-RECIRC	Solenoid — recirc to T-101 (N.O.)	24 VDC coil	+24 V → Y1.NC → coil + ; coil − → 0 V (see below)
Y2	SV-ICE	Solenoid — to ice machine (N.C.)	24 VDC coil	+24 V → Y2.NO → coil + ; coil − → 0 V
Y3	SV-TREAT	Solenoid — to mineral injection (N.C.)	24 VDC coil	+24 V → Y3.NO → coil + ; coil − → 0 V
Y4	FAN-1	Enclosure cooling — intake/exhaust pair 1 (stage 1)	12 VDC switching	+12 V (DDR-15G-12 output) → Y4.NO → fan-pair 1 + ; fan-pair 1 − → DDR 0 V. Energised by the PLC at TT-200 ≥ 95 °F; de-energised below 90 °F deadband. See §5.7 of the system overview and §14.5.
Y5	FAN-2	Enclosure cooling — intake/exhaust pair 2 (stage 2)	12 VDC switching	+12 V → Y5.NO → fan-pair 2 + ; fan-pair 2 − → DDR 0 V. Energised by the PLC at TT-200 ≥ 105 °F; de-energised below 100 °F deadband. Stage 2 supplements stage 1 — both pairs run together at full load.
Y6–Y8	spare	—	—	—

Single-stage fallback: if you'd rather run all four fans together off one relay, wire both intake/exhaust pairs through Y4 only and leave Y5 unused as a spare. The two-stage convention above is the primary design; the fallback is documented for builders who prefer simpler logic at the cost of less granular control. Pick at panel build and document in the as-built; the ladder logic supports either convention with a single flag.

SV-RECIRC fail-state nuance: the spec calls for SV-RECIRC to be normally open (energise to close, de-energise to recirc) so the recirc path is the safe default on power loss / PLC fault. There are two ways to wire this:

1. Use a normally-closed solenoid (energise-to-open) plumbed in the bypass to demand leg. With this convention SV-RECIRC is replaced by a single energise-to-close valve in the recirc return, and the failure default is recirculation. Cleaner electrically.
2. Use the table above with a normally-open solenoid wired through the relay's NC contact, so the coil is de-energised to keep the valve open and only energised to force it closed when SV-ICE or SV-TREAT opens. This matches the spec's "SV-RECIRC fail open" wording literally but consumes one relay continuously.

Build choice — to be confirmed at panel build with the procured solenoid model. The ladder logic supports either convention with a single coil-polarity flag.

Each 24 VDC solenoid coil has a flyback diode across the coil (cathode to +24 V) wired at the field terminal block to suppress the inductive kick when the relay opens.

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10. VFD Power & Motor Wiring

10.1 Line-side (240 VAC input)

Each drive sees, in order:

CB-x (2P breaker)  →  LR2-xx-1PH (line reactor, input side)  →  Drive R/S terminals

Drive	Breaker	Line reactor	Drive input current	Wire (line)
VFD-101 (GS21-21P0)	CB-1, 20 A 2P	LR2-21P0-1PH-A (1 HP, 11.6 A, 3 % Z)	10.8 A CT / 11.3 A VT	10 AWG
VFD-102 (GS21-20P5)	CB-2, 15 A 2P	LR2-20P5-1PH (½ HP, 6.2 A, 3 % Z)	7.3 A CT / 8.3 A VT	14 AWG
VFD-103 (GS21-20P5)	CB-3, 15 A 2P	LR2-20P5-1PH (½ HP, 6.2 A, 3 % Z)	7.3 A CT / 8.3 A VT	14 AWG

The GS21 series in 1-phase mode uses two of three input phase terminals; per the GS20 manual, populate R(L1) and S(L2) and leave T(L3) open. Bond the drive chassis ground stud to the panel ground bus with green 10 AWG.

10.2 Motor-side (drive output → motor)

VFD output to motor uses Southwire VFDC-16-4B-1 (16 AWG, 4 conductors with green/yellow ground, shielded XLPE/TPE) cut to length:

Drive	Motor	Run length	Cable
VFD-101 → P-101 (CRN1S-15)	RO feed pump	TBD on skid	VFDC-16-4B-1
VFD-102 → P-102 (CRN1S-4)	Recirc/transfer pump	TBD on skid	VFDC-16-4B-1
VFD-103 → P-103 (CRN1S-5, 0.33 HP, FLA 1.10 A @ 230 V)	Distribution pump	TBD on skid	VFDC-16-4B-1

Cable termination rules (apply to all three drive-to-motor runs):

• Conductors U / V / W terminate at the drive's U(T1) / V(T2) / W(T3) lugs and at the motor's T1 / T2 / T3 (or U / V / W) leads. Phase rotation is verified with a phase-rotation meter on first start; reverse any two motor leads to correct.
• The cable's green/yellow conductor terminates at the drive's PE ground stud and at the motor's grounding lug.
• The braided shield is grounded at the drive end only with a 360° EMC gland; at the motor end the shield is cut back and insulated. (Single-end shielding avoids the ground loop that would otherwise inject high-frequency switching noise into the analog rail.)
• A lockable disconnect switch is installed within sight of each motor per NEC 430.102, on the motor side of the VFD cable (downstream of the drive). The disconnect is a non-fused door-handle motor switch sized for the motor FLA.

10.3 Drive control wiring

Each GS21's control terminal strip is wired:

Drive terminal	To	Function
MI1	Slot 2 P2-08TRS Y6/Y7/Y8 (.NO contact)	Run command (sink mode, 2-wire start)
DCM	Drive's own +24 V common	Sink-mode common
MO1 (open-collector status)	Slot 1 P2-16ND3-1 X6/X7/X8	Run/Fault status back to PLC
MCM	0 V on TB3	Status common
RJ45 (RS-485)	Modbus daisy chain (see §11)	Speed setpoint, monitoring

Onboard analog speed pots are disabled in drive parameters; speed comes from the PLC over Modbus.

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11. Communications

11.1 RS-485 Modbus RTU — PLC ↔ VFDs

Single daisy-chain bus, PLC P2-550 RS-485 port as Modbus master, three GS21 drives as slaves. Cable: Q8302-1 (single twisted pair, 24 AWG, shielded), cut to length.

[P2-550 RS-485] ─── [VFD-101] ─── [VFD-102] ─── [VFD-103]
        |                                              |
       120 Ω                                         120 Ω
        |                                              |
      shield ───────── (continuous shield, grounded at PLC end only) ─────

Node	Modbus address	Settings
PLC P2-550	master	38 400 baud, 8N1, RTU
VFD-101	1	38 400 baud, 8N1, RTU
VFD-102	2	38 400 baud, 8N1, RTU
VFD-103	3	38 400 baud, 8N1, RTU

• A 120 Ω termination resistor is fitted at the PLC end (across A/+ and B/−) and at VFD-103 (the bus end node). Drives in the middle (-101, -102) are not terminated.
• Q8302-1 has one twisted pair → use the pair for A/B (D+/D−). The shield drain wire is the bus reference and is bonded to the panel ground bus at one point only (PLC end).
• Polarity: AutomationDirect labels the P2-550 RS-485 terminals D+ (= A, non-inverting) and D− (= B, inverting). On the GS21, terminals S+ and S− correspond. Match D+ → S+ and D− → S− across all nodes.
• Stub length from the bus to each drive is kept under 12 in.

11.2 Ethernet — PLC ↔ HMI

• CM5-T10W has dual Ethernet; P2-550 has dual Ethernet. Connection is a single Cat 5e/6 patch cable from one HMI Ethernet port to one PLC Ethernet port — no switch required for this point-to-point link.
• IP plan (factory default, change at commissioning):

Device	IP	Subnet
P2-550 ETH1	192.168.10.10	/24
CM5-T10W ETH1	192.168.10.20	/24

• The second Ethernet port on each device is reserved for a service laptop (programming / diagnostics) — left as default DHCP/auto.

11.3 USB / SD / serial

• Datalogging: an industrial-grade microSD card inserted in the P2-550 captures process variables per system overview §5.6.
• Programming: USB-microB on the P2-550 for Productivity Suite IDE; USB on the CM5 for CM5 Series Software v8.0. Both ports remain accessible without opening the panel (HMI USB is door-side; PLC USB requires opening the panel — acceptable for a maintenance-only port).
• The CM5's RS-232 / RS-485 serial ports are unused in this build; left for future expansion.

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12. HMI Wiring (CM5-T10W)

Connection	Wire	To
24 VDC +	16 AWG blue	TB3 / NDR-120-24 +24 V (own fused branch, 1 A)
24 VDC − (0 V)	16 AWG blue/white	TB3 / NDR-120-24 0 V
Chassis ground	12 AWG green	Panel ground bus via DN-G10-10
Ethernet	Cat 5e/6	P2-550 ETH1

The HMI is door-mounted; the four-wire bundle (24 V, 0 V, ground, Ethernet) routes through a flexible cable carrier to allow the door to swing without cable strain.

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13. Grounding Scheme

A single panel ground bus (DIN-rail-mounted DN-G10-10 grounding terminal blocks bonded to the rail, with the rail bonded to the CP3624G conductive sub-panel) is the reference for all equipment grounding inside the panel.

Sub-panel selection matters. The Hoffman CSD362410 enclosure ships without a sub-panel by default; the sub-panel is procured separately. Use the CP3624G (galvanized, conductive) variant — the plain CP3624 is white-painted steel and is electrically isolated by the powder coat at the rail-mounting points, which would defeat this grounding scheme. With CP3624G, every rail bond and every enclosure-backplate bond is metal-to-metal through the galvanizing.

Host facility ground  ─── 10 AWG green ─── Panel ground bus
                                                 │
                                                 ├── CP3624G conductive sub-panel (bonded)
                                                 ├── DIN rails (each rail bonded to sub-panel)
                                                 ├── Door (bonded to sub-panel via braided strap)
                                                 ├── Drive PE studs (3×, 10 AWG green)
                                                 ├── PLC PSU (P2-01AC) ground
                                                 ├── 24 VDC PSU (NDR-120-24) ground
                                                 ├── HMI chassis (12 AWG green)
                                                 ├── Analog cable shields (drain wire)
                                                 ├── Modbus cable shield (drain wire)
                                                 └── VFD output cable shields (drive end)

0 VDC reference: the negative output of the NDR-120-24 is bonded to the panel ground bus at the PSU. All field-side 0 V returns are referenced to this single point — this gives the 4–20 mA loops and the discrete-input commons a single, clean ground reference.

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14. Enclosure Cooling System

This section covers the build/wiring detail for the forced-air cooling system that lives on top of the panel's electrical design. Why the system exists, what the dose / capacity / placement choices are, and the PLC control logic are in system overview §5.7 and §5.6.

14.1 Bill of materials (cooling-system slice)

Item	Part	Qty	Source
120 mm fan	Noctua NF-A12x25 (12 VDC, ~35 CFM free-air, PWM lead unused)	4	eBay
Magnetic 120 mm dust filter frame	ZYAMY (set of 4)	1 set	eBay
120 mm fan grill	Noctua NA-FG1-12 SX5 (set of 5)	1 set	eBay
24 → 12 VDC DIN-rail PSU	Mean Well DDR-15G-12 (15 W, 1.25 A @ 12 V)	1	Digi-Key
Enclosure-air RTD	Generic PT100 3-wire, waterproof 1 m probe, −50 to +200 °C	1	eBay

14.2 Cutout layout — Hoffman CSD362410 body

Four 4″ (≈ 102 mm) through-holes are added to the enclosure body. Recommended placement:

            ┌───────────────────────────────────┐
            │            (door — door layout    │
            │             unchanged from §2)    │
            │                                   │
  EXHAUST   │   ●─────●           ●─────●       │   EXHAUST
  HIGH      │   │  E  │           │  E  │       │   HIGH
   (top of  │   ●─────●           ●─────●       │   (top of
   side wall│                                   │   opposite
   panel)   │                                   │   side wall)
            │                                   │
            │                                   │
            │   ●─────●           ●─────●       │
  INTAKE    │   │  I  │           │  I  │       │   INTAKE
  LOW       │   ●─────●           ●─────●       │   LOW
   (bottom  │   (filtered, magnetic frame on    │   (filtered, magnetic frame on
   of side  │    exterior face)                 │    exterior face)
   wall)    └───────────────────────────────────┘
                  (rear view — facing the
                   back of the enclosure;
                   left side wall on left)

Key constraints:

• Diagonal flow. Intake low on one side wall + exhaust high on the opposite side wall = air sweeps the full panel volume past the warmest components (drives, line reactors). Stacking intake and exhaust on the same side wall short-circuits the airflow and is not acceptable. The two intake/exhaust pairs are mirrored so each stage independently produces diagonal flow.
• Avoid the sub-panel mounting studs. Lay out the cutouts on the side walls (the 36″ × 10″ faces), not on the back wall, so the sub-panel and DIN rails don't block air-side ingress/egress.
• Avoid the door. Door-mounted fans complicate the HMI cable carrier and the door's gasket seal. Side-wall placement keeps the door clean and the fans serviceable without opening the door.
• Clearance. Reserve at least 50 mm (~2″) of internal clearance behind each cutout so the fan body, grill, and wiring don't foul the DIN-rail mounted components in Zones A–D.
• Filter swap. Magnetic intake filters snap off without tools — confirm the chosen wall lets a hand reach the filter externally for routine cleaning (monthly check; replace when discoloured).

14.3 Mounting hardware

Standard 120 mm fan mounting hole pattern (105 mm × 105 mm on centres, 4× M4 or #6-32). For each fan:

1. Inside face: Noctua NA-FG1-12 SX5 wire grill, 4× M4 screws outboard through the enclosure wall.
2. Enclosure wall: punched 4″ (102 mm) round through-hole, deburred and edge-treated (silicone bead recommended) to prevent abrasion of the fan body.
3. Fan body: Noctua NF-A12x25, oriented so the airflow arrow points into the enclosure (intake fans) or out of the enclosure (exhaust fans). Double-check before tightening — the Noctua label faces the airflow direction.
4. Outside face (intakes only): ZYAMY magnetic dust filter frame, magnetic snap-on. No screws.
5. Outside face (exhausts only): nothing — exhaust path is unfiltered to keep ΔP low.

14.4 TT-200 enclosure RTD placement & wiring

Item	Detail
Sensor	Generic PT100 3-wire waterproof probe, ~100 cm cable, SS sheath, range −50 to +200 °C
Placement	Above the drives, in the panel's warmest pocket (top third of the enclosure, away from intake airflow). Goal: read the air the drives are actually living in, not the air directly off the intake fans.
Mount	Cable-tie or small bracket on the side wall or on an upper DIN rail; do not bond the SS sheath to the panel ground bus — let the probe float so the 3-wire lead-resistance compensation works correctly.
Cable	1 m factory lead routes through the wire duct to TB7 and on to P2-06RTD channel 2 (see §7).
Termination	3-wire to P2-RTB: tie the two leads at the probe end (= EX+ + Sense), the third lead is RTN. Match per the AutomationDirect P2-06RTD wiring diagram.
IDE config	Hardware Configuration → P2-06RTD → channel 2 → Pt100, 3-wire. Engineering units = °F (the rest of the HMI is in mixed US units; pick °F here for operator consistency).

14.5 Relay & fan power wiring

Two cooling fans are paired per relay (one intake + one exhaust per pair), giving diagonal airflow each time a pair energises. The wiring runs from the DDR-15G-12 output, through the P2-08TRS #2 relay's NO contact, to the paired fans, back to the DDR 0 V.

NDR-120-24 +24 V ─┬─────────────────┐
                  │                 │
                  ▼                 │
              DDR-15G-12 IN+   panel 0 V bus
              DDR-15G-12 IN−        │
                  │                 │
                  ▼                 │
              DDR-15G-12 OUT+ (+12 V)
                  │
        ┌─────────┴───────────────┐
        ▼                         ▼
   [P2-08TRS#2 Y4.COM]      [P2-08TRS#2 Y5.COM]
        │  (relay closes)        │  (relay closes)
        ▼                         ▼
   [Y4.NO terminal]         [Y5.NO terminal]
        │                         │
        ▼                         ▼
  INTAKE-A (+) ─────┐         INTAKE-B (+) ─────┐
  EXHAUST-A (+) ────┤         EXHAUST-B (+) ────┤
                    │                            │
                INTAKE-A (−) ──┐             INTAKE-B (−) ──┐
                EXHAUST-A (−)──┤             EXHAUST-B (−)──┤
                               │                            │
                               ▼                            ▼
                       DDR-15G-12 OUT− ◄──────────────── (same return)
                               │
                               └──────► panel 0 V bus

Notes:

• Each relay carries two fans in parallel. Per-fan draw is ~0.14 A @ 12 V → ~0.28 A per relay → trivially within the P2-08TRS 4 A/point rating.
• DDR-15G-12 output common ties to the panel 0 V bus at the converter, not at each fan. Single-point reference keeps the 12 V loop quiet and avoids loops on the 24 V field bus.
• PWM lead on each Noctua: cut back or insulate and tape off at the fan; do not land on the relay. Speed is controlled at the relay (binary on/off), not at the fan.
• Tachometer lead on each Noctua: unused. Cut back or tape off. (If you want fan-failure detection later, the tach can be wired into a P2-16ND3-1 discrete input, but that needs a small pull-up — out of scope for this rev.)
• Use the magnetic filter as a sacrificial mechanical fuse. The fan blades are inboard of the wire grill (see §14.3); the worst-case foreign-object intrusion is at the magnetic filter on the outside face, which lifts off without tools.

14.6 Single-stage fallback wiring (optional)

If the operator prefers to run all four fans together off a single relay (simpler logic, slightly higher noise floor when the panel needs cooling), wire both intake/exhaust pairs through Y4 in parallel and leave Y5 unused as a spare:

DDR-15G-12 OUT+ ─► Y4.COM ─► Y4.NO ─► all 4 fans (+) in parallel
                                       all 4 fans (−) ─► DDR-15G-12 OUT−

Y5 stays as a freely-available spare on P2-08TRS #2. Document the choice in the as-built schematic.

14.7 Cooling-system build sequence (slot into §15)

1. Lay out the four 4″ cutouts on the side walls per §14.2 before mounting the enclosure on the wall (easier to punch on a bench).
2. Punch the cutouts with a 4″ hole saw or chassis punch; deburr and apply a silicone edge bead.
3. Install the four fans (orientation: intakes blow in, exhausts blow out) with grills on the inside face and magnetic filters on the outside face of the two intakes.
4. Route fan power leads through the panel wire duct to the DIN-rail mounted DDR-15G-12 / P2-08TRS #2 / TB-3 area. Trim and insulate the PWM and tach leads.
5. Mount the DDR-15G-12 on the DIN rail near the NDR-120-24. Wire 24 V input from the NDR-120-24 (fused) and 12 V output to the two relay paths per §14.5.
6. Mount the TT-200 RTD probe inside the enclosure above the drives per §14.4; route the 1 m lead through the wire duct to P2-06RTD channel 2.
7. Bench-verify the cooling system before energising the rest of the panel: with the panel on 120 V (CB-4 only), force Y4 / Y5 from the IDE and confirm each pair of fans spins up. Confirm TT-200 reads ambient room temperature (~75 °F) within ± 2 °F.
8. Bring up the two-stage control logic in the PLC per system overview §5.6 and verify the staged ON/OFF transitions against the deadbands by heating the probe gently (cup of warm water around the probe — no need for a heat gun).

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15. Build Sequence (recommended)

1. Punch the four 4″ cooling-fan cutouts on the enclosure side walls per §14.2 before mounting the enclosure on the wall — easier on a bench. Deburr and apply a silicone edge bead.
2. Mount enclosure (Hoffman CSD362410) on the wall using the supplied wall-mount brackets, install the CP3624G conductive sub-panel on the four internal mounting studs, and lay out DIN rails (cut from DN-R35S1) per the §2 zone diagram. Bond each rail to the sub-panel through a DN-G10-10 block, and bond the sub-panel to the panel ground bus.
3. Install P2-01AC and P2-11B base; clip in P2-550 and the five I/O modules in the assigned slots; install P2-RTBs.
4. Install the three drives and three line reactors in Zone B; route line-side wiring through the breakers in Zone A.
5. Install the NDR-120-24 PSU and bring 24 VDC + / − to TB3. Install the DDR-15G-12 24→12 V converter adjacent to the NDR; wire 24 V input (fused) and 12 V output per §14.5.
6. Install the four Noctua NF-A12x25 fans in the side-wall cutouts (intakes blow in, exhausts blow out), with NA-FG1-12 SX5 wire grills on the inside face and ZYAMY magnetic dust filter frames on the outside face of the two intakes. Route the fan power leads through the wire duct to the P2-08TRS #2 / DDR-15G-12 area; trim and insulate PWM and tach leads per §14.5.
7. Mount the TT-200 PT100 enclosure RTD above the drives per §14.4; route its 1 m lead to P2-06RTD channel 2.
8. Populate Zone D terminal strips (TB1 through TB8) with DN-T12-A blocks bookended by DN-EB35MN brackets, capped with DN-EC1210MN. Use DN-24J2Y push-in jumpers to bridge commons within input groups.
9. Wire the PLC backplane to its field terminals per §5–§9.
10. Wire drive-to-PLC control (run, status) per §10.3, then bring up the Modbus daisy chain per §11.1.
11. Wire HMI per §12; bring up Ethernet per §11.2.
12. Cold checkout: continuity-check every wire to terminal map before applying power; megger the VFD output runs.
13. First power-up: energise CB-4 only (controls / brains); verify PLC and HMI come up; verify the DDR-15G-12 reads 12 V on its output and TT-200 reads ambient on P2-06RTD ch 2. Force Y4 / Y5 on P2-08TRS #2 from the IDE and confirm each fan pair spins up. Then energise CB-5 (metering pump power) and CB-6 (UV receptacle / CWC07-00-40V18 contactor) with loads unplugged or disabled. Finally, individually energise CB-1, CB-2, CB-3 and verify each drive boots and reports on Modbus before connecting motors.
14. Connect motors one at a time and bump-test for rotation (correct phase rotation with a phase-rotation meter, then jog at 5 Hz from the PLC).
15. Cooling commissioning: with the panel under load, monitor TT-200 over a representative operating window; tune the stage-1 / stage-2 setpoints and deadbands per system overview §5.6 if the as-installed thermal behaviour differs materially from the 95 °F / 105 °F design defaults.

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16. Open Items

• SV-RECIRC fail-state convention (§9): pick energise-to-close-with-N.O.-solenoid vs. plumbing inversion at panel build.
• UV contactor installation detail: Rev K BOM uses CWC07-00-40V18 for CB-6 / UV-101. Confirm the final pole usage, coil fuse size, and terminal numbering from the installed unit before producing the as-built schematic.
• Ground-fault protection on CB-6: the spec calls for the UV unit to be on a 120 VAC GFCI receptacle (per Pulsar manual); confirm whether the host-facility branch ahead of this panel already provides GFCI, or whether a GFCI-protected DIN-rail receptacle needs to be added inside the panel.
• Field cable lengths (motor runs, sensor runs, Modbus run): record final pull lengths during install and update this document with the as-built values.
• Cooling setpoint tuning (§5.6 / §14): confirm the 95 °F / 105 °F stage-1 / stage-2 setpoints (with 5 °F deadbands) hold internal panel temperature comfortably under the +40 °C / 104 °F Gladiator breaker limit across worst-case shop ambient. Adjust setpoints / deadbands on the basis of TT-200 trends from the first month of operation.
• Fan-failure detection (§14.5): the four Noctua tach leads are unused in Rev D. If a fan fails silently and the magnetic intake filter is clogged at the same time, the over-temp alarm at 115 °F is the only annunciation. Consider wiring the tach leads to spare discrete inputs in a future revision if the install proves filter-cleaning discipline is unreliable.
• Cooling-cutout NEMA derating (§2 / §14): document the post-cutout enclosure rating (~NEMA 12 / IP54) on the as-built nameplate sticker so a future inspector knows the panel is no longer rated NEMA 4 / IP66 even though the enclosure label still reads that way.