Cable conduit fill calculator

Nobody likes surprises on an invoice, a statement or a receipt. Get the number now, understand it by the time you reach the bottom of the page.

The formula behind this is no secret. If a figure looks off, the troubleshooting notes further down almost certainly cover why.

The purpose, stated plainly

Cable conduit fill Canadian calculation tool turns cable and wire sizes into the right choice — mm² or AWG, current rating, voltage drop, conduit diameter. Undersized wire overheats insulation; oversized wire is wasted money.

Where income, tax or contributions are involved, the reference framework is CRA (Canada Revenue Agency) and CPP/QPP and EI — federal 15–33% plus provincial; GST 5% + PST/HST. Between them sits an exact expression.

Overhead runs: add mechanical protection. Canada mixes metric measurement with imperial habits, so Cable conduit fill calculator is arrange to match what people in reality quote here.

The equation and its logic

Example: 25 A load on XLPE cable in conduit at 25°C requires a specific mm² cross-section. Stranded is more flexible but slightly costlier.

Over a 30 m three-phase run the voltage drop is around 1.5% — well inside the 3% standard limit. Voltage drop = 2 × L × I × ρ / S for DC, with an AC correction. Use when designing residential or industrial wiring, powering a motor over a long run (voltage drop), on a solar system (panel–inverter link), for audio or network cable over long distance, or converting between European and US specs.

For 32 A that's 6 mm² (4 mm² would be marginal).

What the calculator does with your input

Solar systems: UV-resistant cable on the DC side. Always pick with 20–25% margin over computed current. Classic: sizing by nominal current without derating for temperature and install method (at 40°C and bunched cables ampacity drops 30–40%). Second: ignoring voltage drop on long runs — a motor at 100 m won't get started on undersized wire.

For runs longer than 50 m verify voltage drop (max 3% lighting, 5% motors). Third: confusing AWG with mm² (12 AWG ≠ 12 mm², it's 3.31 mm²).

The next few lines do more teaching than the previous few paragraphs.

When it makes sense to reach for this

Typical visitors are users in Toronto, Vancouver, Montreal and Calgary comparing offers or checking a bill, so the worked examples below use sensible local values rather than abstract numbers. Every socket circuit is protected by a 16 A breaker on a B curve.

Stranded — for movable connections, machinery, extension cords, automotive. Solid — for permanent installs in walls and conduit.

Where people go wrong

That means the output can be used directly with an accountant, lender or employer in Canada without converting anything. AWG to mm² uses S = 0.012668 × 92^((36-AWG)/19.5) × 1000. The right cable is the difference between an install that runs 30 years trouble-free and one that overheats under first serious load. For international work invariably quote mm² — less confusion.

Using the calculator

• Electrical supply: 120 V / 60 Hz, Type A/B plugs (same as US).
• Units of gauge: Officially metric (km, kg, °C, L) but Imperial holdovers persist: heights in feet/inches, weights in pounds, oven temperatures frequently °F. Grocery pricing usually per 100 g.
• VAT / sales tax: Canada layers federal GST (5%) with provincial sales tax: HST (13–15%) in ON, NB, NL, NS, PE; separate PST/QST in BC, SK, MB, QC (5–9.975%). Alberta and territories charge only the 5% GST.
• Currency & format: Canadian dollar (CAD, $ or C$). Quebec uses comma as decimal (1 000,00 $), rest of Canada uses period.
• Local notes: Amounts on this page use Canadian dollars and metric units, with provincial variation noted where it matters.

Worth knowing before you rely on the result

Cable conduit fill Canadian calculation tool applies the standards for you so cross-section, ampacity and voltage drop line up in one calculation. How this calculation applies in Canada:

Standard is 2.5 mm² copper for a 16 A circuit in PVC conduit up to 25°C. Every figure above applies to Canada specifically and is reviewed when the rules change.

The essence

That is really all there is to it. Revisit the cable conduit fill calculator whenever a parameter moves — small changes compound.