AC Mains Power for Permanent Node Installations

For fixed infrastructure nodes at permanent sites with grid power access, AC mains power provides the most reliable and lowest-maintenance power solution. A well-designed AC power system eliminates battery replacement cycles and enables higher-power configurations.

Power Supply Selection

Most LoRa mesh nodes run on 3.3V or 5V DC internally. For AC-powered installations, you need a reliable AC/DC converter:

USB Wall Adapters

The simplest option for indoor nodes:

• USB-C PD adapter (5V/3A) - Powers any USB-C node (Heltec V3, T-Beam Supreme). $10-20 for quality Anker or Baseus adapters.
• Quality matters - Cheap adapters can cause RF interference. Use a reputable brand with proper EMI filtering. Look for FCC Part 15 Class B certification on the charger.
• UPS integration - A small USB UPS (Anker PowerCore Fusion, Cyberpower CP685AVR with USB output) adds battery backup to any USB-powered node.

DIN Rail Power Supplies

For professional installations in electrical enclosures or server racks:

• Meanwell HDR-15-5 - 5V/3A DIN rail supply, $15-20. Widely used in industrial automation, proven reliable.
• Meanwell HDR-30-12 - 12V/2A DIN rail supply for nodes that accept 12V input (most PoE-powered nodes, some T-Beams with barrel jack).
• DIN rail supplies mount in standard electrical enclosures alongside circuit breakers and terminal blocks.

PoE (Power over Ethernet)

For nodes at locations with Ethernet infrastructure (commercial buildings, outdoor fixtures with Cat5e runs):

• A PoE splitter converts PoE (48V) to 5V/12V for powering a node
• Enables remote power cycling via managed PoE switch (reboot a node from the office)
• Single cable for both data (if using an Ethernet-capable node or Pi-based room server) and power
• Requires Ethernet infrastructure - not practical for standalone outdoor nodes without network connectivity

UPS Integration for Grid-Powered Nodes

Even grid-powered nodes benefit from battery backup:

• Mini UPS modules - IP UPS boards (Waveshare UPS HAT, PiJuice) that sit between the power supply and the Pi or node. Provide 1-4 hours runtime from integrated LiPo.
• Standard UPS - A small APC BE425M ($40) with a 5V USB output provides 30+ minutes runtime for a low-power node and protects against power line surges.
• Lead-acid battery bank - For extended outage protection (24+ hours), a 12V 7Ah SLA battery with a float charger provides very long runtime. Self-discharge rate is higher than LiPo but cells tolerate float charging indefinitely.

Outdoor AC Power Runs

Running power to an outdoor enclosure requires weatherproof wiring:

• Wire gauge: 14 AWG minimum for 15A circuits; 12 AWG for 20A. For low-power nodes, 18 AWG in weatherproof conduit is adequate.
• Weatherproof conduit: PVC conduit (Schedule 40) is the standard for outdoor AC runs. Seal entry points with weatherproof conduit fittings.
• GFCI protection: The NEC requires GFCI protection for all outdoor outlets. Use a GFCI breaker or GFCI outlet at the first outlet in the outdoor circuit.
• Permit requirements: New AC circuit runs typically require an electrical permit. Check local regulations - this is especially important for community networks working on public property.