What size wire for 100 amp service in Canada?

For a single dwelling, 3 AWG copper or 1 AWG aluminum at 75 °C. Canada has no equivalent of the NEC 310.12 83% rule, so a 100 A service does not drop to 4 AWG copper or 2 AWG aluminum. Rule 8-200 sets 100 A as the minimum service for a single dwelling with 80 m² or more of floor area, excluding the basement (60 A below 80 m²).

What size wire for a 100 amp subpanel in Canada?

The same ampacity starting point: 3 AWG copper or 1 AWG aluminum with 75 °C terminations at both ends, plus a neutral if 120 V loads are supplied and an 8 AWG copper or 6 AWG aluminum bonding conductor (Table 16). On a 240 V feeder sized with the Rule 8-102 default of 80 A, 3 AWG copper reaches about 55 m before the drop passes 3%.

Can I use 2 AWG aluminum on a 100 amp breaker in Canada?

2 AWG aluminum is rated 90 A in the 75 °C column of CEC Table 4, which is below 100 A, so it does not meet the ampacity for a 100 A feeder or service. Use 1 AWG aluminum (100 A) or larger.

What load do I use for voltage drop on a 100 A feeder in Canada?

Rule 8-102 says to calculate voltage drop on the connected load of the feeder or branch circuit if it is known, or otherwise on 80% of the rating of the overcurrent device. For a 100 A breaker with unknown load, that is 80 A. The limits are 3% for the feeder or branch circuit and 5% total from the supply side of the consumer's service to the point of use.

What size bonding wire for a 100 amp subpanel in Canada?

8 AWG copper or 6 AWG aluminum, from CEC Table 16 for an overcurrent device up to 100 A (Rule 10-616). If the circuit conductors are made larger to compensate for voltage drop, the bonding conductor is sized from the ampacity of the largest ungrounded conductor instead, which can push it to 6 AWG copper.

Does a 90 °C cable let me use smaller wire for 100 amps?

Usually not. Rule 4-006 limits the conductor to the termination temperature of the equipment. Unmarked equipment rated 100 A or less is treated as 60 °C and most breakers and panelboards are marked 75 °C, so 3 AWG copper T90 or TECK90 is used at its 100 A (75 °C) rating, not its 115 A (90 °C) rating, at least for the first 1.2 m from the termination.

What Size Wire for 100 Amps in Canada? CEC Chart, Distance in Metres

3 AWG copper or 1 AWG aluminum for a 100 A service, feeder or subpanel under the Canadian Electrical Code (Table 2 and Table 4, 75 °C column). Below: the 60 °C answer, the Rule 8-200 service minimum, wire size by distance in metres under Rule 8-102, max run lengths at 120/240, 208 and 600 V, and the Table 16 bonding conductor.

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 100 A breaker in Canada

Minimum conductor for 100 A, not more than three conductors in a raceway or cable, 30 °C ambient.

Conductor and termination rating	Minimum size	Ampacity
Copper, 75 °C (T90, TECK90 or RW90 on 75 °C terminals)	3 AWG	100 A (Table 2)
Copper, 60 °C (unmarked equipment rated 100 A or less)	1 AWG	110 A (Table 2)
Aluminum, 75 °C (ACWU90, RW90 on 75 °C terminals)	1 AWG	100 A (Table 4)

Rule 4-006 sets which column you can use. Where equipment is marked with a termination temperature, use that column. Where it is not marked, equipment rated 100 A or less (or marked for 1 AWG and smaller conductors) is treated as 60 °C, and equipment rated more than 100 A as 75 °C. Most Canadian breakers and panelboards are marked 75 °C, so a 90 °C conductor is still sized from the 75 °C column, at least for the first 1.2 m from the termination. The 90 °C value (115 A for 3 AWG copper) matters only as a starting point for correction factors. See the CEC Table 2 chart for Table 5A (hot locations) and Table 5C (more than three conductors).

100 amp service in a house

Installation	Copper	Aluminum	Rule
Single-dwelling service, 120/240 V	3 AWG	1 AWG	Tables 2 and 4, 75 °C; no 83% reduction
Feeder to a subpanel, garage or shop	3 AWG	1 AWG	Tables 2 and 4, 75 °C
Equipment limited to 60 °C	1 AWG	see Table 4	Table 2, 60 °C

Rule 8-200 sets the minimum ampacity of a single dwelling's service or feeder conductors as the larger of a calculated load (5,000 W for the first 90 m² of living area, 1,000 W for each extra 90 m², plus heating, air conditioning, range, EV charging and other loads at their demand factors) or a floor: 100 A if the floor area, excluding the basement, is 80 m² or more, and 60 A if it is less. So most Canadian houses need at least a 100 A service, and many with electric heat, EV charging or a heat pump calculate higher. The 200 amp guide covers the next step up.

Wire size for 100 amps by distance (metres, 240 V)

Smallest size that keeps a 120/240 V single-phase run at or under the Rule 8-102 3% limit. The 80 A columns use the Rule 8-102 default for an unknown load (80% of a 100 A breaker); the 100 A columns are for a known full load. Ampacity sets the floor, so the table never goes below 3 AWG copper or 1 AWG aluminum.

One-way run length. 3% drop (7.2 V) at 240 V, conductor resistance at 75 °C.
Run	Cu, 80 A	Cu, 100 A	Al, 80 A	Al, 100 A
15 m	3 AWG	3 AWG	1 AWG	1 AWG
20 m	3 AWG	3 AWG	1 AWG	1 AWG
30 m	3 AWG	3 AWG	1 AWG	1 AWG
40 m	3 AWG	3 AWG	1 AWG	1 AWG
50 m	3 AWG	2 AWG	1 AWG	1/0 AWG
60 m	2 AWG	1 AWG	1/0 AWG	2/0 AWG
75 m	1 AWG	1/0 AWG	2/0 AWG	3/0 AWG
90 m	1/0 AWG	2/0 AWG	3/0 AWG	4/0 AWG

Example: a 100 A subpanel in a detached garage 45 m from the house, load not yet known. Rule 8-102 says to use 80 A. 3 AWG copper reaches 55 m at 80 A, so it works. At 75 m, 3 AWG (55 m) and 2 AWG (70 m) both fall short and 1 AWG copper (89 m) is needed. Remember the 5% total limit includes the service conductors and the branch circuits after the subpanel.

Maximum length at 100 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. These are resistance-only figures; large conductors in steel raceway at a low power factor see a little more drop from reactance.

Copper

Size	240 V, 80 A, 3%	240 V, 100 A, 3%	240 V, 80 A, 5%	208 V 3-ph, 80 A, 3%	600 V 3-ph, 80 A, 3%
3 AWG	55	44	93	56	161
2 AWG	70	56	117	70	204
1 AWG	89	71	148	89	257
1/0 AWG	112	89	187	112	324
2/0 AWG	141	113	236	141	409
3/0 AWG	179	143	298	179	516
4/0 AWG	225	180	375	225	651
250 kcmil	266	213	443	266	768

Aluminum

Size	240 V, 80 A, 3%	240 V, 100 A, 3%	240 V, 80 A, 5%	208 V 3-ph, 80 A, 3%	600 V 3-ph, 80 A, 3%
1 AWG	54	43	90	54	156
1/0 AWG	68	54	113	68	196
2/0 AWG	86	69	143	86	249
3/0 AWG	108	87	181	108	314
4/0 AWG	137	109	228	137	395
250 kcmil	161	129	269	162	467
300 kcmil	194	155	323	194	560
350 kcmil	226	181	377	226	654

The 5% column is the whole budget from the supply side of the service to the farthest point of use, so in practice a feeder rarely gets all of it. For your exact load and length, use the Canadian voltage drop calculator or the Canadian wire size calculator, which checks ampacity and Rule 8-102 together.

Bonding and grounding conductors for 100 amps

Bonding conductor (Table 16, Rule 10-616): 8 AWG copper or 6 AWG aluminum for an overcurrent device up to 100 A.
Upsized for voltage drop: when the circuit conductors are increased to compensate for voltage drop, size the bonding conductor from the ampacity of the largest ungrounded conductor instead. The table below shows what that means for common upsizes.
Service bonding: at service equipment, Table 16 is entered with the ampacity of the largest ungrounded conductor. For 3 AWG copper (100 A), that is 8 AWG copper.
Grounding conductor to the electrode (Rule 10-114): not smaller than 6 AWG copper or 4 AWG aluminum, and that size covers every common service size.

Copper circuit conductor	Table 2 ampacity, 75 °C	Copper bonding conductor (Table 16)
3 AWG	100 A	8 AWG
2 AWG	115 A	6 AWG
1 AWG	130 A	6 AWG
1/0 AWG	150 A	6 AWG
2/0 AWG	175 A	6 AWG

How much load can a 100 amp circuit carry?

System	At 100 A	At 80 A
120 V single phase	12.0 kW	9.6 kW
240 V single phase (120/240 V)	24.0 kW	19.2 kW
208 V three phase (120/208 V)	36.0 kW	28.8 kW
600 V three phase (347/600 V)	103.9 kW	83.1 kW

The figures assume a balanced load and unity power factor. A 100 A service at 240 V is 24 kW, which is exactly the Rule 8-200 minimum load for a dwelling of 80 m² or more. Continuous loads on breakers not marked for 100% continuous operation are generally limited to 80% of the rating under Rule 8-104. The amps to watts calculator handles power factor.

CEC vs NEC for 100 amps

The raw ampacities in CEC Tables 2 and 4 match NEC Table 310.16 for these sizes, so the basic answer (3 AWG copper, 1 AWG aluminum) is the same in both countries. The differences: Canada has no 83% dwelling service rule, voltage drop is mandatory under Rule 8-102 rather than an informational note, run lengths and the code itself are in metres, bonding conductors come from Table 16 instead of NEC Table 250.122 (same 8 AWG Cu / 6 AWG Al at 100 A), and provinces adopt different editions: CSA C22.1:24 in Alberta and Saskatchewan, the 2024 Ontario Electrical Safety Code in Ontario, the BC Electrical Code 2024 in British Columbia, and CSA C22.1:21 with amendments in Quebec. For the US version of this page, see wire size for 100 amps (NEC).

Sources

VRI Electrical, Cable Ampacity Tables – CEC / CSA C22.1 (Tables 2 and 4)
CSA Group, CEC Section 8 excerpt (Rule 8-102)
Electrical Industry News Week, Guide to the CE Code, Section 8 and Section 4 (Rules 8-200, 4-006)
City of Fort Saskatchewan, Load calculation form (Rule 8-200 1) b) 100 A / 60 A minimums)
IAEI Magazine, Application of Rule 4-006
SparkShift, CEC Rule 10-114 and Table 16 (grounding and bonding sizes, provincial editions)
Conductor resistance: NEC Chapter 9 Table 8 values at 75 °C, converted to metres

What Size Wire for 100 Amps in Canada? (CEC)