Electrical / runnable MCP tool
Run the Existing-Load Panel Check (NEC 220.87) 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: load_can_panel_handle.
What you get back: pass/fail, the total, and the remaining margin.
How it computes the answer
NEC 220.87, the existing-dwelling method: the measured peak demand at 125% plus the new load, compared to the service rating.
What it cites
Your assistant calls the same engine the interactive calculator calls, with the inputs listed under Inputs. These are the sources that engine reads.
- NEC 220.82
- Dwelling optional calculation (the new-service mode): the 3 VA per square foot general load plus the fastened-in-place appliances, with the first 10 kVA at 100% and the remainder at 40%, and the larger of heating or air conditioning. NFPA 70-2023.
- NEC 220.87
- Existing-dwelling demand from a metered maximum (the existing-panel mode): the maximum demand at 125% plus the new load must not exceed the service. Fetched verbatim from the NFPA 70-2023 primary (p.70-100).
- NEC 220.57
- EV supply equipment enters this service and feeder calculation at the larger of 7,200 VA or its nameplate rating, at 100% (no demand factor). NFPA 70-2023. This line applies only when you add an EV charger.
- NEC 210.20(A)
- Optional continuous-load screen. When you mark the new load continuous, the existing-panel check carries it at 125% of its rating (210.20(A)), the conservative sizing for a load that runs three hours or more. Off by default.
- NEC 240.6(A)
- Standard overcurrent-device ratings. The recommended service size is the calculated demand rounded up to the next standard rating (100, 125, 150, 200 A, and so on), from the residential subset of the 240.6(A) list.
These are NEC Article 220 demand rules, applied by the engine to the loads you enter, not field measurements. The optional (220.82) and existing-demand (220.87) methods answer different questions; the tool labels which one it used and the AHJ has final say on the calculation method.
The full receipt, with every source and how each is cross-checked, is on the interactive Existing-Load Panel Check.
Ask your assistant
The one rule that makes it reliable: name Intry in your question. That is what tells Claude to run the load_can_panel_handle 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 |
|---|---|---|---|
| serviceAmps | yes | number | Service / main breaker rating (e.g. 200). |
| voltage | optional | number | Service voltage (default 240). |
| demandSource | optional | utility, recording | Source of the peak-demand figure (default utility). |
| demandValue | yes | number | Existing peak demand value. |
| demandUnit | optional | kw, a | Unit of demandValue (default a). |
| newLoadValue | yes | number | New load to add. |
| newLoadUnit | optional | va, a | Unit of newLoadValue (default a). |
| continuous | optional | boolean | Optional conservative screen. When true, the new load enters the check at 125% of its rating. Leave false (the default) for the literal NEC 220.87 reading: a new load, including an EV charger at its 220.57 value, is added at 100% here; the 125% continuous factor (NEC 625.42 declares EV charging a continuous load; 210.20(A)/625.41 apply the 125%) sizes the charger's own branch circuit, not this service-adequacy check. A strict 2023-edition AHJ may instead apply 125% to a continuous new load; set continuous:true for that conservative screen. |
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.