Ambient Temperature Derating Check

A current figure taken from a table is a figure at a reference ambient. Desert and rooftop runs are not at that ambient, and the correction is large enough to change a cross-section decision. This check returns the ambient correction factor for a conductor temperature rating, and applies it to a base current your own installation designer has given you.

Site ambient, °C

Conductor temperature rating

Base current at 30 °C, A

—Ambient correction factor

—Corrected current from your base figure, A

—Temperature headroom left, °C

Enter your site ambient and the base current your installation designer gave you.

The 120 °C allowance is an hour budget, not a second rating

Our European route permits 120 °C for a maximum of 20 000 hours across the life of the cable, at a maximum 90 °C ambient. That is a budget you spend, not a temperature you may sit at.

Hours already spent above 90 °C

Hours remaining in the allowance: —

What this model assumes

The correction factor is the square root of the ratio of remaining temperature rise to reference temperature rise, taken from a 30 °C reference ambient. It is the conventional shape of an ambient correction, and it is stated here so you can check it rather than trust it.
The conductor ratings offered are our own published figures: 90 °C as the normal maximum conductor temperature, and 120 °C permitted for a maximum of 20 000 hours at a maximum 90 °C ambient.
Below the 30 °C reference the factor is held at 1. This tool will not uprate a cable for a cold site.
The base current is yours, not ours. We publish no ampacity table, because ampacity depends on installation method, grouping and support, none of which a cable supplier can see.
Ambient is only one correction. Grouping and installation method apply on top of it and are not modelled here.

Tell us your site ambient with your enquiry

Desert and high-ambient sites are the reason our Desert Solar Cable exists as a separate line. If your ambient figure is pushing the correction factor down hard, say so in the enquiry and we will quote against that condition rather than against a default.