Source: https://guthlabs.ai/docs/instruments/series-parallel-resistor-combiner/

instrument / verified-clean

# Series/Parallel Resistor Combiner

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/series-parallel-resistor-combiner/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/series-parallel-resistor-combiner/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/series-parallel-resistor-combiner/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/series-parallel-resistor-combiner/qualification/>)

## Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

**Area**: Electrical & Electronics Engineering

**Tranche**: tranche-2

**Evidence ID**: t2-006

**Ledger rows**: 1

No ledger note is attached.

## Review findings

The two stated formulas are standard for their respective simple topologies, but the spec is not complete enough to verify arbitrary series/parallel networks. The honest label is empty; it should state supported topology depth, accepted units, and handling of zero, empty, invalid, and non-finite resistor values.

### Formula and scope findings

- Rs=ΣRi is correct for resistors connected strictly in series.

- 1/Rp=Σ1/Ri is correct for resistors connected strictly in parallel, provided every resistor value is nonzero and all values use the same resistance unit.

- The specification does not define how mixed or nested series/parallel topologies are represented or evaluated, so it does not fully specify computation of arbitrary series/parallel networks.

- The topology input is ambiguous: it does not state whether topology is limited to a single series or parallel group or can describe nested combinations.

### Unit assumptions

- All resistor values in one calculation must use a common unit, such as all Ω or all kΩ; the resulting Req has that same unit.

- If values carry unit labels, the implementation must convert them to a common unit before applying the formulas.

- Resistor values are assumed to be real, positive values unless zero-ohm ideal shorts are explicitly supported.

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

A zero-ohm resistor in a parallel network makes the reciprocal formula divide by zero, so the instrument must reject the input or implement an explicit ideal-short rule. Results also depend on an explicit resistance-unit convention.

## Errata and corrections

No applied erratum is attached to this unique-name record.

## Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

````
{
  "inputs": {
    "resistors": [
      {
        "value": 100,
        "unit": "ohm"
      },
      {
        "value": 220,
        "unit": "ohm"
      },
      {
        "value": 330,
        "unit": "ohm"
      }
    ],
    "topology": "series"
  },
  "expected_outputs": {
    "Req": {
      "value": 650,
      "unit": "ohm"
    }
  },
  "working": "Rs = 100 Ω + 220 Ω + 330 Ω = 320 Ω + 330 Ω = 650 Ω."
}
````

## Related workflows

[Electronics Power-Rail Designernetworks](<https://guthlabs.ai/docs/instrument-workflows/power-rail/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`

- `evidence-tranche2/tranche2-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`