calc.engineer

wire ampacity

wire_ampacity

Determine minimum wire gauge using NEC Table 310.16 ampacity ratings with full derating. Looks up base ampacity for copper or aluminum conductors at 60°C, 75°C, or 90°C insulation rating, then applies NEC 310.15(C)(1) ambient temperature correction and NEC 310.15(C)(2) conductor count adjustment. Automatically applies the 125% continuous load factor per NEC 210.20(A) when flagged. Returns the minimum AWG that meets the derated requirement, plus a comparison table of all gauges. Different from wire_gauge which focuses on voltage drop — use both together for complete wire sizing. Essential for residential panels, commercial feeders, solar arrays, and EV charging installations.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`conductor`	No	Conductor material. Copper has higher ampacity; aluminum is lighter and cheaper for large feeders.	copper
`insulation`	No	Insulation temperature rating in °C. 60=TW/UF-B, 75=THW/THWN/XHHW (most common), 90=THHN/THWN-2.	75
`current_amps`	Yes	Required circuit current in amperes. Use 125% of continuous load per NEC 210.20(A).
`ambient_temp_c`	No	Ambient temperature in °C. NEC base is 30°C. Higher temps require derating. Typical: 30 (indoor), 40 (attic/hot), 45+ (rooftop conduit).
`continuous_load`	No	Whether the load operates continuously (3+ hours). NEC requires 125% sizing for continuous loads. Set false for intermittent loads.
`conductors_in_raceway`	No	Number of current-carrying conductors in a single raceway or cable. More than 3 requires derating per NEC 310.15(C)(2).

Output Schema

TableJSON Schema

Name	Required	Description
`all_gauges`	Yes	All available gauges with their ampacities for comparison.
`minimum_awg`	Yes	Minimum AWG wire gauge that meets the derated ampacity requirement.
`base_ampacity_a`	Yes	Base ampacity from NEC 310.16 before any derating, in amperes.
`insulation_label`	Yes	Insulation rating description.
`minimum_awg_label`	Yes	Human-readable AWG label (e.g. '4/0', '12', '2').
`ambient_correction`	Yes	Ambient temperature correction factor applied (1.0 at 30°C).
`derated_ampacity_a`	Yes	Final ampacity after applying ambient temperature and conductor count correction factors, in amperes.
`required_ampacity_a`	Yes	Ampacity required to carry the load (includes 125% factor if continuous).
`conductor_count_correction`	Yes	Conductor count correction factor (1.0 for 3 or fewer).

TDQS

A4.6/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description fully carries the burden. It details the derating steps (ambient temperature correction, conductor count adjustment, continuous load factor) and clearly explains what the tool computes and returns.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is moderately long but well-structured: it starts with purpose, then operation steps, then differentiation, then applications. No redundancy; each sentence adds value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 6 parameters with full schema coverage and output schema presence, the description covers the tool's domain (NEC ampacity), inputs, procedure, and output (minimum AWG + comparison table) comprehensively.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so baseline is 3. The description adds context (e.g., '125% continuous load factor per NEC 210.20(A) when flagged') that enriches understanding beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool determines minimum wire gauge using NEC Table 310.16 with derating. It uses specific verbs ('determine', 'looks up', 'applies') and distinguishes itself from sibling tool wire_gauge.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly differentiates from wire_gauge and advises using both together, plus lists typical applications. While it lacks explicit when-not scenarios, the context is clear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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TDQS

A3.9/5.0

Disambiguation4/5

Despite 89 tools, each has a clearly distinct purpose with detailed descriptions that often reference related tools. Overlap exists (e.g., multiple LoRa/RF tools), but the descriptions are sufficient to distinguish them. Some confusion possible among similar-sounding tools like attenuator_pi and attenuator_tee, but the descriptions explicitly compare them.

Naming Consistency4/5

Consistent underscore-separated lowercase naming. Most tools follow a verb_noun pattern (e.g., capacitor_charge, wire_gauge) or noun_noun (power_cost). Minor inconsistencies such as 'bmi_calculator' vs 'solar_sizing' but overall predictable.

Tool Count2/5

89 tools is far too many for a single MCP server. This scope is more appropriate for multiple specialized servers. The sheer number will slow agent selection and increase cognitive load, reducing coherence.

Completeness3/5

Covers many domains (RF, solar, PCB, networking, math, etc.) but lacks depth in some areas (e.g., no three-phase power, no airflow calculations). Some domains have comprehensive coverage (LoRa/Meshtastic), but others feel incomplete for the tool count.

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