Marine Electrical Distribution, Cable Derating, Protection Coordination & Route-Fill Screening

Shipboard Cable Ampacity, Voltage Drop, Breaker & Retrofit Route Capacity Tool

Screen whether an existing or proposed shipboard cable circuit can carry a retrofit load without exceeding derated cable ampacity, voltage-drop limits, breaker protection windows or cable-route capacity. Compare running and starting voltage drop, test breaker interrupting capacity against prospective fault current, calculate minimum parallel runs, and determine whether the existing tray or transit route has enough fill and weight reserve for the added cables.

Currency
Currency selector changes display only. No exchange-rate conversion is performed.

Retrofit Power & Route Basis

Cable ampacity is intentionally entered from the applicable marine cable manufacturer's data or approved project table, then derated for the actual installation. This avoids pretending that conductor size alone determines allowable current onboard ship.

%
Enter the approved project / class / yard limit for this route. The tool does not hardcode a tray-fill rule.
% of route
mm
mm
Cross-sectional route fill is a planning screen only. Spacing, segregation, support and installation rules can govern before simple area fill.
% of route
kg/m
kg/m
$ / cable-m

Simple Circuit Electrical Load

V
kW
%
%
m
× running A
Set near 1.0 for VFD / soft-start or non-motor loads when a high inrush screen is not relevant.
%
%

Cable Ampacity & Impedance Basis

Use 1 for one multicore power cable per run. Enter the actual physical cable count for single-core arrangements.
A
Ω/km
Ω/km
mm
kg/m

Breaker & Fault-Duty Screen

A
Use the relevant breaker rating or long-time protection setting for the project screening basis.
kA
kA
$

Retrofit Circuit Register

Each row is evaluated independently for ampacity, voltage drop and breaker coordination, while all rows share the route-capacity inputs above. Use manufacturer / project cable data for ampacity and impedance.

Circuit System V kW PF Eff % Length m Margin % Parallel Base A Derate R Ω/km X Ω/km Max VD % Breaker A Fault kA Break kA OD mm Phys/run kg/m

Engineering & Installation Readiness

Electrical engineering screen only: This calculator is not a class-approved cable-sizing, protection-coordination, short-circuit, arc-flash, harmonics, EMC, fire-safety, hazardous-area or selective-tripping study. Do not infer cable ampacity from conductor size alone. Use approved marine cable data and the applicable installation / correction factors. Breaker acceptance also requires the correct trip characteristics, selectivity, making / breaking duty and cable short-circuit withstand, which are not fully modeled here.
Current reference context: IEC 60092-352:2025 is the current IEC standard covering selection, installation and operating conditions of fixed shipboard cables, including systems up to Um 18/30 (36) kV. IEC 60092-302-2:2025 covers low-voltage marine power switchgear and controlgear assemblies, and IEC 60947-2:2024 is the current IEC circuit-breaker product standard for the voltage ranges within its scope. Apply the edition, class rules, flag requirements and cable-manufacturer data that govern the actual vessel and project.
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