What size wire do I need for a 50 amp breaker in Canada?

#6 copper NMD90 is the common residential answer; #8 copper T90/RW90 in conduit is acceptable where terminations are 75°C-rated (#8 copper = 50 A in the CEC Table 2 75°C column). #6 aluminum also works at 75°C. Long runs must be upsized — Canada's 3% voltage drop limit is mandatory.

Is NMD90 limited to the 60°C column like American Romex?

No blanket cap — unlike NEC rules for NM-B, NMD90's usable ampacity is governed by the termination-temperature rule (CEC 4-006): 60°C for unmarked equipment, 75°C where breakers and lugs are marked 75°C. In residential practice the common answers land in the same place, and many electricians simply run #6 for 50 A.

What size wire for a 50 amp hot tub in Canada?

#6 copper on a 4-wire circuit with GFCI protection and a disconnect near the tub, per CEC Section 68 practice. Long runs from the panel should be checked against the mandatory 3% voltage-drop limit.

🔌 What Size Wire for 50 Amps in Canada?

The Canadian answer — where the cable is NMD90, not Romex, and the rules are subtly different. 🇺🇸 US version

The short answer

For a 50 amp, 240 V circuit at ordinary distances in Canada: #6 copper NMD90 is the common residential answer, and #8 copper T90/RW90 in conduit is acceptable where the terminations are 75°C-rated (#8 copper = exactly 50 A in the 75°C column of CEC Table 2). #6 aluminum works at 75°C. Past about 30 m, the mandatory drop limit pushes you bigger — table below.

The Canadian twist on the #6 vs #8 debate

Americans argue #6 vs #8 because their code hard-caps Romex (NM-B) at the 60°C column. Canada's equivalent cable, NMD90, has no such blanket cap — what limits it is the termination rule (CEC 4-006): unmarked devices are treated as 60°C, breakers marked 75°C allow the 75°C column. In practice, Canadian electricians still commonly run #6 NMD90 for 50 A — it's unambiguous, inspector-friendly, and leaves margin — while #8 in conduit with 75°C-marked equipment is defensible by the book. When a rule has this much room for debate (and Canadian forums debate it plenty), the bigger wire is the quieter life. Check any combination in the Ampacity Check tool.

Distance changes the answer — and in Canada it's enforceable

CEC Rule 8-102 makes the 3% drop limit mandatory. Minimum size at 240 V and 50 A (one-way distance):

Material	15 m (50′)	30 m (100′)	46 m (150′)	61 m (200′)	76 m (250′)	91 m (300′)
Copper	8	6	4	4	3	2
Aluminum	6	4	3	2	1	1/0

AWG sizes (Canada uses AWG like the US), sized at the full 50 A. The 2024 CEC lets you calculate at connected load — or 80% of the breaker when unknown — so these sizes carry built-in margin. Exact run: Wire Size calculator.

The common Canadian 50-amp jobs

Hot tub: 4-wire circuit with GFCI protection and a disconnect near the tub (CEC Section 68 governs pools and tubs) — #6 copper is the standard install. EV charger: charging is a continuous load, so a 50 A circuit delivers at most 40 A continuously under the CEC's continuous-load rules — conductors sized to the 50 A breaker, same table as above; many Canadian installs also use the 347/600 V commercial world at work sites, but home charging is 240 V. RV receptacle (14-50): same sizing; a pedestal 46 m out routinely needs #4 — and in Canada that upsize is code, not courtesy. Welder: CEC gives welders duty-cycle allowances similar to the US — the manual's smaller-than-expected wire spec can be legitimate.

Worked example: 50 A hot tub at 24 m (80 ft)

#6 copper (26,240 cmil): drop = 2 × 12.9 × 50 × 80 ÷ 26,240 = 3.9 V = 1.6% of 240 V — comfortably inside the mandatory 3%. In #8 (16,510 cmil): 6.3 V = 2.6% — passes, with less headroom. Run yours in the Voltage Drop calculator.

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