AGL Series Cable Loop Loss Calculator
Loop resistance, voltage drop and heat loss of a series lighting circuit cable from its length, size, material and temperature.
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Estimate only. Not engineering or safety advice. Check the result against the applicable standard and the equipment data, and have a competent engineer review it before it is relied on. Terms of use.
Open in the calculator with these values
About this calculator
This page calculates loop resistance, per unit length, voltage drop in the cable and 1 more result from circuit current, series cable loop length, cable cross-section, conductor material and 1 more input. Change any value or its unit and the result updates. The steps below show the working for the default values, so you can check each line against your own method.
Limits of this calculator
Use the result as the cable loss in the CCR sizing and brightness step calculators. Confirm the cable resistance against the manufacturer data for the cable you install.
Cross-check: 25 reference cases, calculated from textbook formulas coded separately from the engine by the same author, agree with this calculator. This is not an independent review.
Verification status: Engineering reference
Engineering reference. Formula and method documented and tested against separately coded reference calculations. Not yet Verified: the evidence listed on this page is still needed.
What this calculator checks
- The arithmetic of the published formula for the values you entered, in the units shown.
What remains unverified
- That the inputs suit your application. Take ratings, resistances and constants from the manufacturer data sheet or project specification.
Verification register entry
| Calculation author | Rahul Sharma (author) |
|---|---|
| Technical review | No independent technical review has been carried out |
| Individual professional approval | Not recorded |
| Formula reference | not recorded |
| Standard and edition | IEC 61820-1-2; IEC 60228, IEC 61820-1-2:2024; IEC 60228:2023 Ed 4.0 |
| Standard review state | Public-scope screened; licensed clause review still pending |
| Scope-screening note | AGL series-circuit cable context and conductor resistance/size requirements are relevant. The calculator estimates loop resistance and I²R loss; confirm cable construction, circuit topology, operating temperature and actual manufacturer resistance. |
| Cross-check test cases | 25 reference vectors (tests/reference_vectors.json) |
| Review date | not recorded |
| Next review date | not recorded |
| Status | Engineering reference |
Needed before this calculator can be marked Verified: reviewer name, qualification and review date; licensed clause-by-clause standard review; exact formula reference; formula source (textbook or standard); next review date.
Formula
Worked example
| Input | Value |
|---|---|
| Circuit current | 6.6 A |
| Series cable loop length | 4,000 m |
| Cable cross-section | 6 mm² |
| Conductor material | Copper |
| Conductor temperature (°C) | 20 |
- ρ(T) = 1.7241e-8 × (1 + 0.00393 × (20 − 20)) = 1.7241e-8 Ω·m
- R = ρ(T) × 4,000 m / 6 mm² = 11.494 Ω
- Vd = 6.6 A × 11.494 Ω = 75.9 V
- Loss = 6.6² × 11.494 = 501 W
Assumptions
- Copper 1.7241e-8 Ω·m and aluminium 2.8264e-8 Ω·m at 20 °C, with 0.00393 and 0.00403 per °C
- DC resistance of the full loop, no skin or proximity effect
- The same current flows through the whole loop
Use the result as the cable loss in the CCR sizing and brightness step calculators. Confirm the cable resistance against the manufacturer data for the cable you install.
Inputs and results
| Input | Unit | Allowed or shown | Note |
|---|---|---|---|
| Circuit current | A | greater than 0 A | |
| Series cable loop length | m | greater than 0 m | Out and back, the full length of the series loop |
| Cable cross-section | mm² | greater than 0 mm² | |
| Conductor material | (choice) | Copper; Aluminium | |
| Conductor temperature (°C) | (number) | -50 or more, up to 150 | Resistance rises about 0.39% per °C for copper |
| Result | Unit | Allowed or shown | Note |
|---|---|---|---|
| Loop resistance | Ω | Shown to 3 decimal places | |
| Per unit length | Ω/km | Shown to 3 decimal places | |
| Voltage drop in the cable | V | Shown to 1 decimal place | |
| Cable loss | W | Shown to 0 decimal places |
How it is calculated
Each input is converted to the base unit of its quantity, the formula above is applied in the order shown in the worked example, and each result is shown in the unit you choose. Results are held at full precision and rounded only for display, except where a step selects a standard size, as the worked example shows. A value outside its allowed range is refused with a message instead of giving a result.
How the result changes with circuit current
| Circuit current (A) | Loop resistance (Ω) | Per unit length (Ω/km) | Voltage drop in the cable (V) |
|---|---|---|---|
| 0.66 | 11.494 | 2.873 | 7.6 |
| 1.65 | 11.494 | 2.873 | 19 |
| 3.3 | 11.494 | 2.873 | 37.9 |
| 6.6 | 11.494 | 2.873 | 75.9 |
| 13.2 | 11.494 | 2.873 | 151.7 |
| 26.4 | 11.494 | 2.873 | 303.4 |
| 66 | 11.494 | 2.873 | 758.6 |
Other inputs are the same as in the worked example above.
Standards and further reading
- ICAO Annex 14, Volume I (aerodrome design and operations)
- ICAO Doc 9157, Part 5 (aerodrome design manual, electrical systems)
Photometric and circuit requirements come from the edition of Annex 14 and the regulator's rules that apply at your aerodrome, and from the fitting and regulator manufacturers' data. These are named as background reading. Elecmetric does not embed clause text or rating tables, and the reviewer record for this calculator is separate from this list.
Frequently asked questions
What do I need to enter?
Enter circuit current, series cable loop length, cable cross-section, conductor material and conductor temperature (°C). Change the unit of a value with its selector and the result stays the same.
What does this calculator assume?
Copper 1.7241e-8 Ω·m and aluminium 2.8264e-8 Ω·m at 20 °C, with 0.00393 and 0.00403 per °C. DC resistance of the full loop, no skin or proximity effect. The same current flows through the whole loop.
Which calculators should I use next?
Common next steps are AGL Series Circuit Load and CCR Size, AGL Maximum Fittings on a CCR and Cable Resistance. The related links at the bottom of this page open them.
How accurate are the results?
Every figure comes from the same tested engine as the Elecmetric calculators and is meant for estimating. 25 reference cases, calculated from textbook formulas coded separately from the engine by the same author, agree with this calculator. This is not an independent review. Check design values against the standard and the equipment data you work to.
Formula guides and reference
Longer explanations with worked examples and tables, written for the same topic.
- Cable Loss Formulas: Power and Annual Cost: Cable power loss formulas: I squared R loss for single-phase and three-phase cables, annual energy and cost of the loss
- AGL Series Circuit Load and CCR Sizing Formulas: AGL series circuit formulas: the load of a 6.6 A constant current circuit, the cable loss
- Conductor Resistance Formulas and Temperature: Conductor resistance formulas: resistance from length, area and resistivity, correction for temperature
More Airport and AGL Engineering calculatorsAll engineering calculatorsAGL Series Cable Loop Resistance and Loss in Elecmetric