How To Choose the Right PVC Conduit Size
What each diameter in the 10 to 40 mm ladder is actually used for, and why over-sizing costs more than it saves.
The Size Ladder
Shingfong extrudes 10, 16, 20, 25, 32 and 40 mm. Each step exists because a different class of wiring needs it, not because the market likes choice.
10 mm and 16 mm
10 mm is for small gauge wire: telephone, alarm and data drops where the point is separation rather than capacity. 16 mm is the smallest size most electricians will accept for a lighting circuit.
20 mm and 25 mm
20 mm is the default for domestic and light commercial wiring; it balances the space wire needs against how easy the run is to fix and conceal. 25 mm gives room for several wires to sit without tangling and for a later circuit to be drawn in.
32 mm and 40 mm
32 mm serves commercial and larger residential distribution where power, lighting and data share a route. 40 mm is for large diameter cable in industrial and multi-storey commercial work.
Why Over-Sizing Costs Money
A larger pipe costs more per metre, needs larger clips and fittings, and is harder to hide in a wall or ceiling void. Size for the cable you are pulling plus a margin for one future circuit, not for every possibility.
What We Extrude
10mm PVC Conduit
The 10 mm PVC conduit is the smallest size in the Shingfong ladder and exists for one job: keeping small gauge wire separate and tidy.
View product →20mm PVC Conduit
20 mm is the size most installers reach for first.
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25mm PVC Conduit
25 mm is the step where a run stops serving one circuit and starts serving several.
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40mm PVC Conduit
40 mm is the top of our standard ladder and is built for large diameter cable: factory power distribution, high current feeds and the main runs in multi-storey commercial buildings.
View product →Quick Answers
Is conduit sized on outside or inside diameter?
Our sizes refer to the outside diameter, with the wall thickness printed on the pipe. Ask for the specification sheet if you need the exact bore for a cable calculation.
Which size should a wholesaler stock deepest?
20 mm and 25 mm move fastest in most markets because they cover domestic and light commercial work.
Need This Specified for a Project
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