Free Tool  |  AS/NZS 3000 & BS 7671  |  No Signup

Conduit Fill
Calculator

How many cables fit in your conduit? Enter your conduit size and cable types to calculate fill percentage and check compliance with AS/NZS 3000 and BS 7671.

Free. Works on mobile. Standards-compliant.

Calculate Your Conduit Fill

Select your conduit size, add cables, and see the fill percentage instantly.

Conduit Type & Size

Max 40% fill for more than 2 wires (AS/NZS 3000 / BS 7671)

Cables in Conduit

Why Use This Calculator

Free — no signup required
Supports TPS, single core, and flexible cables
PVC and steel conduit options
AS/NZS 3000 and BS 7671 compliant
Shows remaining capacity for additional cables
Works on mobile for on-site use

Frequently Asked Questions

What is the maximum conduit fill percentage?

Per AS/NZS 3000 and BS 7671: maximum 40% fill for 3 or more cables, 31% for 2 cables, and 53% for 1 cable. This ensures adequate heat dissipation and allows for easy cable pulling.

How many TPS cables fit in 25mm conduit?

A 25mm PVC conduit can typically fit 3-4 runs of 2.5mm\u00B2 TPS 2C+E cable at the 40% fill limit. The exact number depends on the cable outer diameter.

Why is conduit fill limited to 40%?

The 40% fill limit ensures adequate air space around cables for heat dissipation, prevents excessive friction during cable pulling, and reduces the risk of cable damage during installation.

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