Electrical / runnable MCP tool
Run the Voltage Drop Calculator in your AI assistant
Through the free Intry MCP server, Claude, ChatGPT, or Cursor runs this exact calculator and hands back a verdict and the cited source, not a guess. Tool name: voltage_drop.
What you get back: THREE sizes and they are not interchangeable: the voltage-drop-only minimum (a recommendation), the ampacity minimum at standard conditions (a requirement), and the minimum overall, which is the LARGER of the two per 210.19(A).
How it computes the answer
Computed from NEC Chapter 9 Table 9 (effective-Z) or Table 8 (K-method); the 3%/5% flag is the advisory 210.19/215.2 recommendation, not a code limit.
What it cites
Your assistant gets the same verdict and the same citation a technician gets on the interactive calculator, because both call one engine. These are the sources that engine reads.
- NEC Chapter 9, Table 9
- AC resistance and reactance (ohms per 1000 ft) for building conductors, used for the effective-Z method. The effective impedance is computed from the table's R and XL at your power factor (0.85 by default, the table's own basis). Fetched verbatim two-pass from the NFPA 70 primary and cross-checked against the 2005-cycle CEC.
- NEC Chapter 9, Table 8
- Conductor circular-mil area, used for the simple K-method (2 × K × I × L / CM single-phase, √3 for three-phase; K = 12.9 copper, 21.2 aluminum). Fetched from the primary.
- NEC 210.19 and 215.2 Informational Notes
- The 3% branch-circuit and 5% total voltage-drop figures are an NEC recommendation, not an enforceable limit. We flag against that recommendation and say so; the honest ceiling is that this is advisory guidance, not a code maximum.
The resistance and reactance are NEC table values looked up by the engine; the drop and percentage are computed from them and the run you enter. The 3%/5% verdict is advisory guidance, not a code limit, and is labeled that way.
The full receipt, with every source and how each is cross-checked, is on the interactive Voltage Drop Calculator.
Ask your assistant
The one rule that makes it reliable: name Intry in your question. That is what tells Claude to run the voltage_drop tool and answer with the real number, the verdict, and the citation. Leave Intry out and Claude may just guess from memory, which is exactly what you are trying to avoid. Type something like:
Inputs
| Field | Required | Accepts | What it is |
|---|---|---|---|
| wireSize | yes | 14, 12, 10, 8, 6, 4, 3, 2, 1, 1/0, 2/0, 3/0, 4/0, 250, 300, 350, 400, 500, 600, 700, 750, 800, 900, 1000, 1250, 1500, 1750, 2000 | Conductor size, AWG or kcmil (e.g. '12', '1/0', '250'). |
| amps | yes | number | Load current in amps. |
| length | yes | number | One-way run length in feet. |
| voltage | optional | number | System voltage (default 240). |
| phase | optional | single, three | single or three phase (default single). |
| material | optional | cu, al | cu = copper, al = aluminum (default cu). |
Add Intry to Claude
One paste and Claude can run this tool and every other Intry calculator, right from your phone.
- Claude opens with the Intry connector already filled in. Review it and click Add.
- (If a field is blank, paste the link below into the URL field.)
- In any chat, tap + then Connectors and switch Intry on. Then name Intry in your question (“use Intry to…”) so Claude runs the tool instead of guessing.
https://www.intrysys.com/api/mcpNo login, no API key, and it works on every Claude plan, right from your phone.
Using ChatGPT, Cursor, or a dev tool? See the developer setup on the main page. The endpoint is https://www.intrysys.com/api/mcp.
Every answer comes with the cited NEC section, so you can check it or show an inspector. The numbers come from the same calculator we run on intrysys.com, and we re-check every one automatically before anything goes live, so the number Claude hands you matches the code.