EleCanada
Raceway geometry

Conduit area ratio calculator

Compare the circular area of supplied cables with the clear circular bore supplied for a raceway. This is a geometric ratio, not a raceway fill limit or installation decision.

Calculation inputs

Raceway and cable dimensions

Clear raceway bore
mm

Enter an actual verified clear inside diameter. Do not use nominal trade size or outside diameter as a substitute.

Cable group 1
mm

Use the actual cable's overall outside diameter, including insulation and jacket where present.

Enable JavaScript to edit cable groups and calculate.

Geometric area ratio

Enter a verified clear bore and at least one complete cable group.

This result is a geometric comparison only. It is not an allowable fill percentage, a code determination, proof that cables can be installed, or a raceway-size recommendation.

What it calculates

Enter the verified clear inside diameter of a circular raceway and one or more groups of round cables. Each cable uses its actual overall outside diameter. The calculator compares the sum of cable cross-sectional circle areas with the area of the supplied circular bore.

This geometry helper does not complete the raceway fill or raceway selection task. It supplies no adopted rule, permitted percentage, raceway capacity table or product-specific internal dimensions.

Method and example

For raceway clear inside diameter D, bore area is πD²/4. For each cable outside diameter d, area is πd²/4; multiply by quantity and sum all groups. The ratio is total cable area divided by bore area, multiplied by 100.

For a supplied 100 mm clear bore, four 10 mm cables and two 20 mm cables have a combined area of approximately 942.478 mm². The circular bore area is approximately 7,853.982 mm², giving a geometric area ratio of 12%. These supplied dimensions illustrate arithmetic only.

Limits

The clear bore and cable outside diameters are user-supplied. This tool does not derive them from raceway trade size, manufacturer catalogues, construction tolerances or conductor-area tables. It assumes circular cross sections solely for area arithmetic.

The ratio does not model cable arrangement, spacing, layer count, bend or pull geometry, lubrication, raceway length, pulling tension, material loading, ampacity, temperature or code requirements. It does not select a raceway or determine whether a cable route is installable.

Do not compare this value with a code limit or use it to approve an installation. Full raceway fill remains pending reviewed Canadian rule branches, approved raceway and conductor data, jurisdiction scope and qualified technical review.

Common questions

Can the ratio be above 100%?

Yes. The displayed ratio is not capped; above 100% the summed cable circle areas exceed the supplied bore area. It does not provide a packing or pass/fail result.

Can I enter nominal raceway trade size?

No. Enter an actual verified clear inside diameter in millimetres. Nominal size and outside diameter do not establish the bore area.

Does this calculate allowable raceway fill?

No. Applicable adopted requirements, cable construction, exact raceway capacity and installation conditions require a separately reviewed method.

These tools calculate other geometric or cable-layout quantities.

Cable tray areaCompare round-cable area with a supplied rectangular tray area.Conduit bendLay out supported offset, segment and saddle marks.PVC expansionEstimate Scepter PVC movement and piston settings.

Source

The formulas are circle area A = πd²/4 and area ratio 100 × total cable area ÷ supplied bore area. The calculator uses only user-supplied dimensions and does not derive them from an electrical code or manufacturer table.

Report a problem or suggest a source. Cable inputs are not included automatically.