Electrical / runnable MCP tool
Run the Conduit Fill 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: conduit_fill.
What you get back: fill %, the limit, remaining capacity, jam risk, and the next size up if over.
How it computes the answer
Computed from NEC Chapter 9 Table 1 (fill percent), Table 4 (conduit area), and Table 5 (conductor area).
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 1
- Maximum percent of conduit cross-section that may be filled: 53% for one conductor, 31% for two, 40% for three or more, and the Note 4 nipple allowance (60%) for a raceway 24 in. or shorter. Fetched two-pass from the primary.
- NEC Chapter 9, Table 4
- Internal cross-sectional area of each conduit and tubing type by trade size, for the raceway types this tool supports (EMT, IMC, RMC, PVC-40, PVC-80, ENT); the usable area is that internal area times the Table 1 percentage. Fetched two-pass from the primary.
- NEC Chapter 9, Table 5
- Approximate cross-sectional area of each insulated conductor by AWG/kcmil and insulation type (THHN/THWN, XHHW, and others). Fetched two-pass from the primary.
These are NEC Chapter 9 table values, looked up and summed by the engine for the conductors you enter, not measurements. The result is the code fill calculation; the installer still confirms the actual conductors and raceway on site.
The full receipt, with every source and how each is cross-checked, is on the interactive Conduit Fill Calculator.
Ask your assistant
The one rule that makes it reliable: name Intry in your question. That is what tells Claude to run the conduit_fill 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 |
|---|---|---|---|
| conduitType | yes | EMT, IMC, RMC, PVC40, PVC80, ENT | EMT, IMC, RMC, PVC40, PVC80, or ENT. |
| conduitSize | yes | 1/2, 3/4, 1, 1-1/4, 1-1/2, 2, 2-1/2, 3, 3-1/2, 4 | Trade size, e.g. '3/4'. |
| nipple | optional | boolean | Is this a nipple ≤24" (60% fill, no derate)? Default false. |
| conductors | yes | array of { size: 1 | 2 | 3 | 4 | 6 | 8 | 10 | 12 | 14 | 250 | 300 | 350 | 400 | 500 | 600 | 700 | 750 | 800 | 900 | 1000 | 1/0 | 2/0 | 3/0 | 4/0; insulation: THHN | THWN-2 | XHHW | XHHW-2 | RHH* | RHW* | RHW-2* | TW | THW; qty: number } | Conductors in the raceway. |
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.