Equipment: multimeter, current-limited isolated 5 V bench supply, 3.3 V USB-UART adapter, oscilloscope if available.
First tests must be performed with all mains wiring disconnected.
Do not apply 230 VAC until the PCB enclosure, clearances, terminals, contactor, fuse/breaker, PE bonding, and wiring have been inspected by a qualified person.
Never connect the pump directly to the PCB relay.
1. Visual Inspection
Verify PS1, U1, U2, Q1 and D1 orientation.
Verify K1 is the 5 V coil variant.
Check separation between CTRL_MAINS_L/CTRL_MAINS_N/contact nets and 5V_SELV/3V3_SELV/GND_SELV.
Confirm J5-J9 external representations are not populated on the PCB.
Home Assistant/ESPHome water-pump controller using an ESP32-C3-WROOM-02-N4 Wi-Fi module. The controller energizes an external motor-rated contactor; it does not switch pump current directly.
Applicable Regulatory Areas
FCC Part 15 intentional radiator requirements for US marketing.
CE Radio Equipment Directive (RED) for EU marketing.
EMC and electrical safety requirements for a mains-powered controller.
Local installation codes for fixed 230 VAC pump equipment.
Wireless ModuleRF Integration Requirements
Preserve the module antenna keepout specified by Espressif on every copper and mechanical layer.
Place the antenna at a board edge with no enclosure metal, mains wiring, contacto...
Received notification from "ESP32 Pump Controller Verification" that it finished — picking the work back up.
The schematic is fully wired with 20 nets and independently verified: power, ESP32 support, relay driver, manual override, isolation, and external pump path all pass ERC with no warnings or errors.
Open items: Final contactor, fuse/breaker, coil suppression, and mains clearances require the pump nameplate and PCB layout.
A Wi-Fi/Home Assistant controller for a single-phase 220 V AC water pump. The electronic controller commands an external motor-rated contactor; a BTicino wall switch independently forces the contactor ON. The pump branch is protected by a replaceable fuse or certified breaker.
Intended Use
Fixed indoor installation in a suitable insulated electrical enclosure by a qualified mains electrician. This is not a direct breadboard or exposed-PCB mains project.
What the Device Should Do
Expose pump ON/OFF control to Home Assistant through ESPHome.
Default the automatic command OFF after controller reboot.
Allow an ordinary BTicino switch to force the pump ON if Wi-Fi, Home Assistant, or the controller is unavailable.
Ensure the manual switch and automatic relay form a parallel OR function.
Switch motor power with an external AC-3-rated contactor, not a small PCB relay.
Protect the pump branch with a motor-appropriate fuse/breaker.
Main Features
ESP32 Wi-Fi module running ESPHome.
Certified isolated 220 VAC to 5 VDC power module for controller electronics.
3.3 V regulator sized for ESP32 Wi-Fi current peaks.
Transistor-driven 5 V interposing relay with flyback protection.
Relay dry contact rated for 250 VAC controlling only the contactor coil.
External BTicino switch wired in parallel with the relay contact for manual-ON override.
External contactor main pole switches the pump line conductor.
System Architecture
Diagram
Hardware Subsystems
Mains and motor branch
External fuse/breaker in series with line before the contactor and pump.
External 2-pole contactor preferred where local rules require disconnecting both conductors; otherwise switch line and keep neutral unswitched.
Contactor utilization category: AC-3, provisionally at least 16 A at 220-240 VAC; select higher if the pump nameplate or starting duty requires it.
Controller power
Certified encapsulated isolated AC-DC supply, nominal 5 V / at least 1 A.
3.3 V regulator capable of at least 600 mA peak with required input/output capacitors.
Wi-Fi control
ESP32 module with PCB antenna and programming/reset access.
Automatic control output must initialize LOW/OFF.
Contactor-coil interface
5 V relay driven by an NPN transistor or logic MOSFET.
Flyback diode across the relay coil.
Relay contact and BTicino switch wired in parallel to feed the external 230 VAC contactor coil.
The PCB relay does not carry pump current.
Interfaces and Connections
J1: 220 VAC controller supply input, L/N/PE as required.
J2: contactor-coil control terminals.
J3: BTicino manual-override switch terminals.
J4: low-voltage programming/debug connector or pads.
External power path: supply line -> fuse/breaker -> contactor -> pump; neutral and PE per local code.
Power and Runtime Expectations
Continuous mains operation. No battery. Controller power is independent of pump current.
Power Tree and Power Budget
Table
Rail
Load
Typical
Peak/design
3.3 V
ESP32 Wi-Fi module
120-240 mA
500 mA
3.3 V
status/support circuitry
5-20 mA
30 mA
5 V
relay coil
70-100 mA
120 mA
5 V
3.3 V regulator input equivalent
~250 mA
~530 mA
5 V total
all controller loads
~350 mA
~650 mA
Use a certified 5 V supply rated at least 1 A. The provisional pump load is 12 A at 220 VAC, separate from the controller power budget.
Manufacturing and Assembly Expectations
Production-intent PCB with SMD low-voltage components and certified mains-rated modules/components.
Mains screw terminals and enclosure must be touch-safe and correctly rated.
Maintain reinforced/basic insulation distances according to the installation category, pollution degree, material group, and applicable standard.
Do not route SELV copper through the mains isolation corridor.
Firmware-Relevant Hardware Requirements
ESPHome native Home Assistant API.
Restore mode: automatic relay always OFF after reboot.
GPIO output must have a hardware pull-down or otherwise remain inactive through boot.
Optional status reporting can indicate automatic command state; it cannot reliably infer actual pump state without an auxiliary contact or current sensor.
Physical Design Expectations
ESP32 antenna at the PCB edge with all-layer copper/component keepout.
Mains and SELV functional areas visibly separated.
Install in a flame-retardant DIN-rail or electrical enclosure away from water and condensation.
Important Design Decisions
Use an external motor contactor rather than switching a presumed 12 A pump through a PCB relay.
Manual BTicino switch is a force-ON override in parallel with automatic control.
Manual override cannot force OFF while Home Assistant commands ON.
Controller failure does not prevent manual ON, provided mains power and the contactor path remain healthy.
Assumptions
220-240 VAC single-phase supply.
12 A is a provisional running-current estimate, not a verified nameplate value.
External contactor has a 220-240 VAC coil.
Indoor fixed installation; environmental/IP rating remains to be defined.
Final fuse/breaker curve and rating require pump nameplate current, power, and starting method.
Success Criteria
Home Assistant commands energize/de-energize the external contactor in AUTO operation.
BTicino switch energizes the contactor independently when automatic command is OFF or unavailable.
Controller reboot leaves automatic output OFF.
No pump load current passes through the PCB relay or PCB traces.
ERC has no unresolved critical connectivity errors.
Change Notes
Initial architecture established from user requirements on 2026-08-17.