The chain is what matters: loads give you daily consumption, consumption gives you the bank, the bank and the run length give you the gauge, and the gauge comes with the fuse — so changing one load re-derives the rest instead of invalidating a page of hand maths. The wire gauge tool checks both ampacity and voltage drop, which is the calculation people usually get wrong on long runs, and the diagram fills in the shunt, main switch and cutoff rather than waiting to be asked.
Domain arithmetic for low-voltage DC electrical systems, plus a schematic generator. Eight calculators run locally and deterministically; the ninth renders the diagram.
- Daily energy draw from a list of loads — watts, hours a day and quantity — returned as Wh and Ah with peak and average power
- The battery bank that consumption implies, given days of autonomy and depth of discharge, with the number of batteries and how to wire them
- The series and parallel arrangement to reach a target voltage and capacity, expressed as a configuration like 2S3P with step-by-step wiring instructions
- Solar wattage to recharge that daily draw, accounting for peak sun hours and system losses including MPPT conversion and temperature derating
- Cable gauge in mm² and AWG for a run, chosen against both ampacity and voltage drop, with total resistance, power lost as heat and a fuse recommendation
- Inverter size for AC loads with startup surge and 25% continuous headroom, plus the DC current it will draw
- Charging time from one state of charge to another, split into the bulk phase and the slower absorption phase above about 80%
- A complete schematic as SVG or PNG — batteries, chargers, loads — with the shunt, main switch and low-voltage cutoff generated automatically when both batteries and loads are given
- The component types and example configurations to build a diagram from
Nothing to authorize. The simplest route is the hosted endpoint https://mcp.voltplan.app/mcp over streamable HTTP — a URL in your client config and nothing installed. Locally, npx wiring-diagram-mcp runs it over stdio from the npm package wiring-diagram-mcp, currently 0.2.2, and a Docker image serves HTTP on port 3001. VOLTPLAN_API_URL points at a different API instance. The calculations run inside the server with no network call; the diagram rendering is the part that reaches the VoltPlan API and returns the SVG or PNG your client embeds.
One command — claude mcp add wiring-diagram --transport http https://mcp.voltplan.app/mcp