Are Canadian wire ampacity tables the same as American ones?

For the common building sizes, yes — CEC Table 2 (copper) and Table 4 (aluminum) are harmonized with NEC Table 310.16, verified value-by-value for 14 AWG through 4/0. What differs is the surrounding rules: cable-type treatment (NMD90 vs NM-B), derating tables, and Canada's mandatory voltage-drop limit.

How many amps can 12 gauge wire handle in Canada?

20 amps on a 20 A breaker for ordinary circuits — CEC 14-104 caps #12 copper at a 20 A overcurrent device, the same as the US rule, even though the 75°C and 90°C columns list 25 and 30 A.

Is NMD90 limited to 60°C like American NM-B?

No blanket cap. NMD90 has 90°C insulation and follows the termination-temperature rule (CEC 4-006): 60°C for unmarked equipment, 75°C where equipment is so marked, with the 90°C column mainly serving as the derating starting point.

🔥 Wire Ampacity Chart — Canada (CEC Table 2 & Table 4)

The Canadian copper and aluminum table — harmonized with the US values, governed by Canadian rules. 🇺🇸 US version

The chart

Amps each wire can carry continuously under the CEC (up to three current-carrying conductors in a raceway or cable, 30°C ambient). Good news for anyone working both sides of the border: CEC Table 2 (copper) and Table 4 (aluminum) are harmonized with the US NEC's Table 310.16 — we verified the values match, so this is one chart for both countries:

Size	Copper (Table 2)			Aluminum (Table 4)
Size	60°C	75°C	90°C	60°C	75°C	90°C
14 AWG	15	20	25	—	—	—
12 AWG	20	25	30	15	20	25
10 AWG	30	35	40	25	30	35
8 AWG	40	50	55	35	40	45
6 AWG	55	65	75	40	50	55
4 AWG	70	85	95	55	65	75
3 AWG	85	100	115	65	75	85
2 AWG	95	115	130	75	90	100
1 AWG	110	130	145	85	100	115
1/0	125	150	170	100	120	135
2/0	145	175	195	115	135	150
3/0	165	200	225	130	155	175
4/0	195	230	260	150	180	205

Values verified against Canadian sources (and against US reproductions — they match). Small-conductor breaker caps apply in Canada too (CEC 14-104): #14 copper → 15 A breaker, #12 → 20 A, #10 → 30 A, regardless of column. Interactive version: Ampacity Check.

Which column am I allowed to use? (the NMD90 story)

Same principle as everywhere: use the column of your weakest link (CEC Rule 4-006). Wire insulation may be rated 90°C — NMD90 and T90 both are — but the breaker lugs and device terminals set the ceiling: unmarked equipment counts as 60°C, equipment marked 75°C allows the 75°C column. Here's the difference from the US that trips up cross-border readers: American Romex (NM-B) is hard-capped at the 60°C column by a blanket rule; Canadian NMD90 is not — it follows the termination rule like any other 90°C conductor. In everyday residential work the answers land in the same familiar places (#14 → 15 A, #12 → 20 A, #10 → 30 A), but the 90°C rating gives NMD90 a better starting point when derating for heat or bundling.

Does voltage change ampacity?

No. A #10 wire carries the same ~30 A at 12 V, 120 V, 240 V, or Canada's commercial 347/600 V. What voltage changes is the sting of voltage drop — 3 lost volts is 1.3% of a 240 V circuit but 25% of a 12 V one. And remember: in Canada the drop limit is mandatory (Rule 8-102).

What this chart doesn't cover

Normal conditions only. Hot environments, bundles of more than three current-carrying conductors, and continuous loads all reduce these numbers — and note that Canada's bundling-derate table (Table 5C) differs from the US one, so cross-border derating advice doesn't transfer. A derating tool is on our roadmap.