Power supply lines incorporate ferrite beads in series, presenting high impedance to high-frequency noise while allowing DC and low-frequency signals to pass unattenuated.
Parallel Drive Protection - The Arduino control architecture places both house-based Arduino AR1 and shed-based Arduino AR3 in position to command relays under different operational modes.
To prevent GPIO conflicts if both Arduinos simultaneously attempt to drive the same relay line (one HIGH, one LOW), each Arduino's output connects through an IN5819 Schottky diode to the shared relay control line, with a 10kΩ pull-down resistor to ground.
This wired-OR configuration ensures that if either Arduino drives HIGH, the relay sees HIGH, while both must release for the line to fall to LOW, preventing the direct short circuit that would occur if two GPIOs were directly paralleled.
Water Ingress Protection - While the pump shed itself is not waterproof (deliberate gaps allow air intake for diesel combustion), critical electronics in the polycarbonate IP66 enclosure remain protected from direct spray. The enclosure mounting positions it away from the shed cooling spray pattern, and small ventilation baffles (one near top, one near bottom) allow heat dissipation while preventing water entry. All external cable entries use cable glands with compression seals. The RS-485 transceivers, battery terminals, and high-current relay contacts reside outside the sealed enclosure but are positioned to avoid direct spray contact.
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