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What Size Wire for 30 Amps in Canada? (CEC)

10 AWG copper or 8 AWG aluminum for a 30 A circuit under the Canadian Electrical Code. CEC Table 2 rates 10 AWG copper at 30 A even in the 60 °C column, and Rule 14-104(2) stops anything smaller from going on a 30 A breaker. Below: the small-conductor rule, dryers, water heaters, 24 A EV chargers, wire size by distance in metres under Rule 8-102, max run lengths at 120, 240, 208 and 600 V, the Table 16 bonding conductor and how much load a 30 A circuit carries.

CEC data notice: CEC values were checked against public summaries of CSA C22.1:24, not the code book itself. Conduit and conductor areas use NEC Chapter 9 data, and some aluminum kcmil ampacities are unverified. Confirm against the CEC edition and provincial amendments adopted where you work.

Quick answer: wire size for a 30 A breaker in Canada

Minimum conductor for 30 A, not more than three conductors in a raceway or cable, 30 °C ambient.

ConductorMinimum sizeWhy
Copper (any termination rating)10 AWG30 A at 60 °C (Table 2); Rule 14-104(2) allows 30 A
Aluminum, 60 °C or 75 °C8 AWG35 A at 60 °C (Table 4); 10 AWG Al is capped at 25 A
NMD90 cable (house wiring)10/2 or 10/310 AWG copper with a bare bond

Because 10 AWG copper carries 30 A in the 60 °C column, the Rule 4-006 question that decides the 50 A and 60 A answers (are the terminals marked 75 °C?) does not change the copper size at 30 A.

Rule 14-104(2): why 12 AWG never goes on a 30 A breaker

Table 2 and Table 4 give the small sizes more ampacity than their breaker limits. Rule 14-104(2) caps the overcurrent protection for these conductors, so for 14 to 10 AWG the breaker cap, not the table, sets the answer.

CEC Table 2 (copper), Table 4 (aluminum) and Rule 14-104(2). Not more than three conductors, 30 °C ambient.
Size60 °C75 °C90 °CMax breaker, Rule 14-104(2)
14 AWG copper15 A20 A25 A15 A
12 AWG copper20 A25 A30 A20 A
10 AWG copper30 A35 A40 A30 A
8 AWG copper40 A50 A55 ATable ampacity
12 AWG aluminum15 A20 A25 A15 A
10 AWG aluminum25 A30 A35 A25 A
8 AWG aluminum35 A40 A45 ATable ampacity
6 AWG aluminum40 A50 A55 ATable ampacity

The exceptions are rules that specifically allow a larger device for certain equipment, such as motors (Section 28) and electric heating (Rule 62-114). Table 13 (the next-standard-size permission in Rule 14-104(1)) does not override the small-conductor caps.

Common 30 A circuits in Canadian homes

Electric dryers

Most residential electric dryers are on a 30 A, 120/240 V circuit with a 14-30R receptacle, wired in 10/3 NMD90 (two hots, a neutral and the bare bond). Use the dryer's nameplate and installation instructions for the breaker size. A long run to a laundry room at the far end of the house is the case to check against the distance table below.

Electric storage-tank water heaters

Rule 62-402 sends storage-tank water heaters to the heating rules in Rule 62-114, which apply the continuous-load ratings of Rule 8-104. In practice the breaker is sized at 125% of the element current (the heater's full-load current), and the heater must be on a branch circuit that supplies nothing else. Common Canadian tank ratings at 240 V:

Single element on at a time, 240 V. Current = watts ÷ 240. Always use the heater nameplate.
ElementCurrent125%BreakerCopper
3,000 W12.5 A15.6 A20 A12 AWG Cu
3,800 W15.8 A19.8 A20 A12 AWG Cu
4,500 W18.8 A23.4 A25 A10 AWG Cu
5,500 W22.9 A28.6 A30 A10 AWG Cu

A 3,000 W tank on a 20 A breaker with 12 AWG copper is common. The usual 4,500 W tank needs 23.4 A, so it goes on 10 AWG copper with a 25 A or 30 A breaker as the nameplate allows. Some provinces have interpretations under Rule 62-114 that differ for small heaters, so check with your inspector.

Level 2 EV chargers and other loads

Wire size for 30 amps by distance (metres)

Smallest size that keeps a run at or under the Rule 8-102 3% limit. The 24 A columns use the Rule 8-102 default for an unknown load (80% of a 30 A breaker); the 30 A columns are for a known full load.

120/240 V single phase (dryer, water heater, EV, subpanel)

One-way run length. 3% drop (7.2 V) at 240 V, conductor resistance at 75 °C.
RunCu, 24 ACu, 30 AAl, 24 AAl, 30 A
10 m10 AWG10 AWG8 AWG8 AWG
15 m10 AWG10 AWG8 AWG8 AWG
20 m10 AWG10 AWG8 AWG8 AWG
25 m10 AWG10 AWG8 AWG8 AWG
30 m10 AWG10 AWG8 AWG6 AWG
40 m8 AWG8 AWG6 AWG6 AWG
50 m8 AWG6 AWG6 AWG4 AWG
60 m6 AWG6 AWG4 AWG4 AWG
75 m6 AWG4 AWG4 AWG3 AWG
100 m4 AWG4 AWG3 AWG2 AWG

120 V (RV pedestal, 30 A receptacle)

One-way run length. 3% drop (3.6 V) at 120 V, copper at 75 °C.
RunCu, 24 ACu, 30 A
5 m10 AWG10 AWG
10 m10 AWG10 AWG
15 m10 AWG10 AWG
20 m8 AWG8 AWG
25 m8 AWG6 AWG
30 m6 AWG6 AWG
40 m6 AWG4 AWG
50 m4 AWG4 AWG

Example: a 30 A circuit to a detached garage 45 m away, load not yet known. Rule 8-102 says to use 24 A. At 240 V, 10 AWG copper reaches only 37 m, so step up to 8 AWG, which reaches 59 m. The same run at 120 V is much tighter: 10 AWG reaches 18 m and 8 AWG 29 m, so it takes 6 AWG (46 m). The 5% total limit includes the service and any feeder upstream, so leave room for them.

Maximum length at 30 amps by wire size

The longest one-way run, in metres, before each size reaches the drop shown. Three-phase columns use the √3 formula and are resistance-only figures.

Copper

Size120 V, 24 A, 3%240 V, 24 A, 3%240 V, 30 A, 3%240 V, 24 A, 5%208 V 3-ph, 24 A, 3%600 V 3-ph, 24 A, 3%
10 AWG1837306237109
8 AWG2959479959172
6 AWG46937415593268
4 AWG74148118247148428
3 AWG93186149311186538
2 AWG117235188392235680
1 AWG148296237494297857

Aluminum

Size120 V, 24 A, 3%240 V, 24 A, 3%240 V, 30 A, 3%240 V, 24 A, 5%208 V 3-ph, 24 A, 3%600 V 3-ph, 24 A, 3%
8 AWG1836296036104
6 AWG2856459456163
4 AWG45907215090259
3 AWG5611390189113327
2 AWG71143114238143413
1 AWG90180144301180521
1/0 AWG113227181379227656

For your exact load and length, use the Canadian voltage drop calculator or the Canadian wire size calculator, which checks ampacity, Rule 14-104 and Rule 8-102 together.

Bonding conductor for 30 amps

When more than three wires share a raceway

CEC Table 5C multiplies the ampacity by 0.80 for 4 to 6 conductors and 0.70 for 7 to 24. Starting from the 90 °C column of T90 Nylon, 10 AWG copper gives 40 × 0.80 = 32 A, still enough for 30 A. At 7 to 24 conductors it drops to 28 A, so upsize to 8 AWG (55 × 0.70 = 38 A). The final ampacity still can't exceed the termination column. See CEC Table 5C for the full chart and hot-location factors.

How much load can a 30 amp circuit carry?

SystemAt 30 AAt 24 A (80%)
120 V single phase3.6 kW2.9 kW
240 V single phase (120/240 V)7.2 kW5.8 kW
208 V three phase (120/208 V)10.8 kW8.6 kW
600 V three phase (347/600 V)31.2 kW24.9 kW

Balanced load, unity power factor. Rule 8-104 limits a continuous load on a breaker not marked for 100% continuous operation to 80% of its rating. The amps to watts calculator handles power factor.

CEC vs NEC for 30 amps

The answer is the same in both countries: 10 AWG copper, because CEC Rule 14-104(2) and NEC 240.4(D) put the same 30 A cap on 10 AWG copper, and both cap 10 AWG aluminum at 25 A, so 8 AWG aluminum is needed in either country. The differences: voltage drop is mandatory in Canada under Rule 8-102 (3% per circuit, 5% total) instead of an informational note, and the code works in metres. The bonding conductor is smaller in Canada: CEC Table 16 gives 12 AWG copper for a 30 A device, while NEC Table 250.122 gives 10 AWG copper. For the US version with feet, see wire size for 30 amps (NEC). For larger Canadian circuits, see 50 amps, 60 amps, 100 amps and 200 amps.

Sources

Frequently asked questions

What size wire for 30 amps in Canada?

10 AWG copper. CEC Table 2 rates it 30 A at 60 °C and 35 A at 75 °C, and Rule 14-104(2) allows a 30 A breaker on 10 AWG copper but not on anything smaller. In aluminum, use 8 AWG: 10 AWG aluminum is capped at 25 A by Rule 14-104(2). Runs longer than about 37 m at 240 V (or 18 m at 120 V) need a larger size to stay within the Rule 8-102 3% limit.

Can I use 12 AWG wire on a 30 amp breaker in Canada?

No. Table 2 lists 12 AWG copper at 25 A (75 °C) and 30 A (90 °C), but Rule 14-104(2) caps the overcurrent protection on 12 AWG copper at 20 A. Only other rules that specifically allow it, such as the motor rules in Section 28, permit a larger device.

Is 10 AWG aluminum OK for 30 amps in Canada?

No. Table 4 rates 10 AWG aluminum 25 A at 60 °C and 30 A at 75 °C, but Rule 14-104(2) limits its overcurrent protection to 25 A. A 30 A circuit in aluminum needs 8 AWG (35 A at 60 °C).

What size wire for a dryer in Canada?

Most electric dryers in Canada are on a 30 A, 120/240 V circuit with a 14-30R receptacle, wired in 10 AWG copper (10/3 NMD90 with a bare bond in a house). Follow the dryer nameplate and installation instructions, and size up for long runs with the distance table on this page.

What size wire for a 30 amp subpanel in Canada?

10 AWG copper or 8 AWG aluminum for the ungrounded conductors and the neutral, plus a bonding conductor of at least 12 AWG copper or 10 AWG aluminum from Table 16. At the Rule 8-102 default load of 24 A, 10 AWG copper reaches about 37 m at 240 V before passing 3%; past that, 8 AWG reaches about 59 m.

What size bonding wire for a 30 amp circuit in Canada?

12 AWG copper or 10 AWG aluminum, from the CEC Table 16 row for overcurrent devices rated over 20 A up to 30 A (Rule 10-616). Above 30 A and up to 60 A it becomes 10 AWG copper or 8 AWG aluminum. In NMD90 cable the bare bonding conductor is already sized for the cable.

How much can a 30 amp breaker carry continuously?

Under Rule 8-104, a continuous load on a breaker not marked for 100% continuous operation is limited to 80% of its rating, which is 24 A on a 30 A breaker: 5.8 kW at 240 V or 2.9 kW at 120 V. That is why a 24 A Level 2 EV charger goes on a 30 A circuit, and why Rule 8-102 uses 24 A as the default load for voltage drop when the actual load is unknown.

Related calculators, charts and guides

Wire Size for 50 Amps (Canada, CEC)What size wire for 50 amps in Canada: 8 AWG copper or 6 AWG aluminum at 75 °C, 6 AWG copper at 60 °C (CEC Tables 2 and 4, Rule 4-006), wire size by distance in metres under Rule 8-102, max run length at 240, 208 and 600 V, and the Table 16 bonding conductor.Wire Size in Canada (CEC Table 2)CEC Table 2 copper and Table 4 aluminum ampacities (14 AWG to 4/0), wire size by breaker for 15 to 200 A, Table 5A hot-location and Table 5C more-than-three-conductor derated charts, Table 1 free air and Rule 8-102.Wire Size Calculator (Canada, CEC)Canadian wire size calculator and charts by amps and distance in metres (copper 120/240 V, aluminum), CEC Table 2/4, Rule 14-104 and the 3% Rule 8-102 voltage drop limit.Wire Size for 30 AmpsWhat size wire for 30 amps: 10 AWG copper or 8 AWG aluminum (NEC 310.16, 240.4(D)), why 12 AWG fails, dryers and 14-30 outlets, water heaters, 24 A EV chargers and 30 A RV hookups, wire size by distance at 120 and 240 V, ground and conduit.