Can I use 14 gauge wire on a 20 amp breaker in Canada?

Use 12 AWG copper NMD90 for an ordinary 20 A branch circuit. CEC Rule 14-104 caps 14 AWG copper at 15 A, so it cannot be protected by a 20 A overcurrent device for this ordinary use.

How far can I run 12 gauge wire on 20 amps in Canada?

12 AWG is the starting answer, but the permitted distance depends on voltage and load. Use the Canadian distance guide or enter the exact run in the Wire Size calculator.

What about 20 amps at 240 V?

The ampacity floor stays 12 AWG copper at 20 A, but 240 V gives more voltage-drop room than 120 V. Enter the actual distance and voltage in the Wire Size calculator.

🔌 What Size Wire for a 20 Amp Circuit in Canada?

🇺🇸 US version

The short answer

Use 12 AWG copper NMD90 for an ordinary 20 A circuit. Do not put 14 AWG copper on a 20 A overcurrent device for this ordinary use.

CEC Rule 14-104 caps 14 AWG copper at 15 A and 12 AWG copper at 20 A for ordinary circuits. NMD90's higher insulation rating does not erase the overcurrent-device cap. Ampacity Check tool.

Distance changes the answer — and the CEC limit is mandatory

Minimum copper size at 120 V, sized at the full 20 A and kept at or under the mandatory 3% voltage-drop limit (one-way distance):

20 A at 120 V

Material	15 m (50′)	30 m (100′)	46 m (150′)	61 m (200′)	76 m (250′)	91 m (300′)
Copper	10	8	6	4	4	3

Small-gauge aluminum branch-circuit wire is not shown. Use copper here; check any other wiring method in the Ampacity Check tool. Wire Size calculator.

Common Canadian 20-amp jobs

Kitchen circuits, bathrooms, garage receptacles, and general lighting are common 20 A jobs. The equipment instructions, provincial amendments, and inspection authority still control the final design.

Worked example: 20 A at 120 V over 30 m (100 ft)

Our verified calculator selects #8 copper (16,510 circular mils): 2 × 12.9 × 20 × 100 ÷ 16,510 = 3.13 V, or 2.6% of 120 V. It passes ampacity and the mandatory 3% drop limit.

How far can you run 12 gauge wire in Canada? · Wire Size calculator · Ampacity Check tool

20-amp wire size FAQ

Can I use 14 gauge wire on a 20 amp breaker in Canada?: Use 12 AWG copper NMD90 for an ordinary 20 A branch circuit. CEC Rule 14-104 caps 14 AWG copper at 15 A, so it cannot be protected by a 20 A overcurrent device for this ordinary use.
How far can I run 12 gauge wire on 20 amps in Canada?: 12 AWG is the starting answer, but the permitted distance depends on voltage and load. Use the Canadian distance guide or enter the exact run in the Wire Size calculator.
What about 20 amps at 240 V?: The ampacity floor stays 12 AWG copper at 20 A, but 240 V gives more voltage-drop room than 120 V. Enter the actual distance and voltage in the Wire Size calculator.