Wire Size Chart: AWG Ampacity & Amp Ratings (NEC 310.16)

A wire size chart gives the maximum current each conductor size may carry continuously — its ampacity — for copper and aluminium at each insulation temperature rating. This one is NEC Table 310.16, the table nearly every wire size chart on the internet is copied from, with one column most of them leave out: the largest breaker each size may be protected by.

That column is where charts mislead people. The highest ampacity printed in a conductor's row is usually not the number you are allowed to design to. 12 AWG copper is rated 30 amps at 90°C, and NEC 240.4(D) still limits it to a 20-amp breaker. Reading the row without reading the limit is how a 12 AWG circuit ends up behind a 30-amp breaker.

Figures here follow NFPA 70-2023. For how conductor sizing works as a subject — the AWG scale, insulation types, derating, the code rules behind these numbers — see wire sizes explained.

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Wire Size Chart: Copper and Aluminum Ampacity

NEC Table 310.16 gives the allowable ampacity of insulated conductors rated up to 2000 volts, for not more than three current-carrying conductors in a raceway, cable or direct burial, at an ambient temperature of 30°C (86°F). Those are the conditions almost every residential and light commercial circuit is installed under, which is why this is the table people mean when they say "the wire size chart".

This chart is print-optimised: printing the page gives the tables, their source and the NEC edition on their own, with no navigation.

Table 1 — Allowable ampacity and maximum overcurrent protection, 14 AWG to 500 kcmil
Wire size	Copper (amps)			Aluminum (amps)		Max breaker (amps)
Wire size	60°C	75°C	90°C	75°C	90°C	Max breaker (amps)
AWG sizes
14 AWG	15	20	25	—	—	15
12 AWG	20	25	30	20	25	20
10 AWG	30	35	40	30	35	30
8 AWG	40	50	55	40	45	50
6 AWG	55	65	75	50	55	60
4 AWG	70	85	95	65	75	80
3 AWG	85	100	115	75	85	100
2 AWG	95	115	130	90	100	110
1 AWG	110	130	145	100	115	125
1/0 AWG	125	150	170	120	135	150
2/0 AWG	145	175	195	135	150	175
3/0 AWG	165	200	225	155	175	200
4/0 AWG	195	230	260	180	205	225
kcmil sizes
250 kcmil	215	255	290	205	230	250
300 kcmil	240	285	320	230	260	250
350 kcmil	260	310	350	250	280	300
400 kcmil	280	335	380	270	305	300
500 kcmil	320	380	430	310	350	350

Source: NEC Table 310.16, NFPA 70-2023 — allowable ampacities of insulated conductors rated up to 2000 V, 60°C through 90°C, not more than three current-carrying conductors in a raceway, cable or earth, at an ambient temperature of 30°C (86°F). Maximum breaker applies NEC 240.4(D) and 240.6(A) to the 75°C copper column.

Ampacity does not scale with gauge the way the numbers suggest. Four steps up from 14 AWG to 6 AWG roughly triples the copper figure, 20 to 65 amps, while the four steps from 1/0 to 4/0 add only 80 — the bars make that curve visible in a way eighteen rows of digits cannot. The second bar in each row is the same conductor in aluminum, and the gap between the pair is the "two sizes larger" rule drawn to scale: 4/0 aluminum reaches 180 amps, which is roughly where 2/0 copper already sits. Every figure plotted is in the wire size chart above, which is the chart's text alternative.

In short: 14 AWG copper is good for 15 amps, 12 AWG for 20, 10 AWG for 30, 8 AWG for 50 and 6 AWG for 65 at 75°C — and the first three of those are capped by the breaker limit, not by the ampacity column. Aluminium runs one to two sizes behind copper the whole way down: 4/0 aluminium carries 180 amps where 4/0 copper carries 230.

Which Temperature Column Applies to Your Circuit?

75°C terminations

In practice that decides the column before you look at the wire. Breakers, panel lugs, receptacles and equipment terminals for circuits up to 100 amps are overwhelmingly listed 60/75°C, which puts almost all residential branch-circuit work in the 75°C column or lower.

60°C terminations

NM-B cable — the flat white, yellow and orange cable in most houses — is held to the 60°C column by NEC 334.80 no matter what its individual conductors are rated, which is why 12-2 NM-B on a 20-amp circuit is sized from 20 amps and not from 25.

When 90°C is usable

The 90°C column still earns its place: it is the legal starting point for derating. Where ambient temperature correction or conductor bundling adjustment applies, the calculation begins at the conductor's own 90°C ampacity and the result is then capped at the terminal-rated value. That is worth real money on a crowded conduit — a 12 AWG THHN conductor derated from 30 amps lands higher than the same conductor derated from 25.

Where to check the rating

Check the equipment, not the wire. The rating is stamped on the breaker, and where a terminal carries no marking, NEC 110.14(C)(1) treats equipment rated 100 amps or less as 60°C. How the temperature rating relates to insulation type is covered on wire sizes explained.

How Many Amps Can Each Wire Size Handle?

Working the chart backwards — from a gauge in your hand to the current it may carry — gives a different answer for each of the six sizes that cover most residential work.

14 AWG copper

15 A at 75°C

Capped at 15 A by NEC 240.4(D)(3)
12 AWG copper

20 A at 75°C

Capped at 20 A by NEC 240.4(D)(5)
10 AWG copper

30 A at 75°C

Capped at 30 A by NEC 240.4(D)(7)
8 AWG copper

50 A at 75°C

No small-conductor cap — 40 A inside NM-B cable
6 AWG copper

65 A at 75°C

No small-conductor cap — 55 A in the 60°C column
4 AWG copper

85 A at 75°C

No small-conductor cap — 65 A in aluminium

14 AWG

14 AWG copper handles 15 amps. Table 310.16 rates it 15 at 60°C, 20 at 75°C and 25 at 90°C, and NEC 240.4(D)(3) caps its overcurrent protection at 15 amps whichever column applies. It is the smallest conductor permitted for a general-purpose branch circuit, and lighting circuits are its usual home.

12 AWG

12 AWG copper handles 20 amps. The table rates it 20, 25 and 30 amps across the three columns; NEC 240.4(D)(5) caps it at 20. This is the size behind kitchen and bathroom receptacles, garage outlets and most 20-amp general-purpose circuits.

10 AWG

10 AWG copper handles 30 amps. Rated 30, 35 and 40 amps across the columns, capped at 30 by NEC 240.4(D)(7). A 30-amp electric dryer, a small water heater and a 30-amp RV outlet all land here.

8 AWG

8 AWG copper handles 50 amps on 75°C terminations, where the table rates it 50. The small-conductor rule stops at 10 AWG, so nothing caps 8 AWG below its ampacity — but inside NM cable it is held to the 60°C column and 40 amps, which is why a 50-amp circuit run in NM-B needs 6 AWG instead.

6 AWG

6 AWG copper handles 65 amps at 75°C, 55 at 60°C and 75 at 90°C. It is the usual conductor for 50-amp and 60-amp circuits: a range, a 48-amp EV charger, a hot tub, or a subpanel feeder.

4 AWG

4 AWG copper handles 85 amps at 75°C, which covers an 80-amp feeder comfortably. Aluminium of the same size handles 65 amps, one of the clearest illustrations of why the two materials are never interchangeable at equal gauge.

Each of those answers assumes a single circuit in ordinary conditions. The terminations at each end, the length of the run, and the heat or crowding around the conductor each change the answer, and each has its own section on this page.

What Size Wire for Common Breaker Sizes?

The conductor a breaker needs is the smallest size whose ampacity in the governing temperature column equals or exceeds the breaker rating, with the NEC 240.4(D) cap applied to 14, 12 and 10 AWG. These pairings assume 75°C terminations, copper or aluminium as marked, and no derating.

Breaker	Copper	Aluminum	Typical use
15 A	14 AWG	12 AWG	Lighting, general-purpose receptacles
20 A	12 AWG	10 AWG	Kitchen and bathroom receptacles, garage outlets
30 A	10 AWG	8 AWG	Dryer, small water heater, RV outlet
40 A	8 AWG	6 AWG	Range, 32-amp EV charger
50 A	8 AWG	6 AWG	Range, 40-amp EV charger, welder
60 A	6 AWG	4 AWG	Hot tub, subpanel feeder, air handler
100 A	3 AWG	1 AWG	Subpanel feeder, detached garage
125 A	1 AWG	2/0 AWG	Large subpanel feeder
150 A	1/0 AWG	3/0 AWG	Small service, large subpanel
200 A	3/0 AWG	250 kcmil	Standard residential service feeder
400 A	2 sets of 3/0 AWG	2 sets of 250 kcmil	Large residential, light commercial

In short: 15 amps takes 14 AWG copper, 20 takes 12 AWG, 30 takes 10 AWG, 50 takes 8 AWG, 60 takes 6 AWG, 100 takes 3 AWG and a 200-amp feeder takes 3/0 — with aluminium one to two sizes larger at every step.

Two conditions change those rows. A 50-amp circuit wired in NM-B cable needs 6 AWG copper rather than 8, because NEC 334.80 holds that cable to the 60°C column. And a dwelling service or main power feeder rated 100 to 400 amps may be sized at 83% of its rating under NEC 310.12, which is why a 200-amp house service is commonly run in 2/0 copper or 4/0 aluminium rather than the 3/0 shown here.

Why This Chart May Differ From Other Wire Size Charts

Cross-check this chart against another one and you may get a different number, and there are only four reasons that happens. Knowing which one is in play tells you which chart to trust.

Reason 1 — the column

A different temperature column. A chart that prints one ampacity per size has silently chosen a column. Charts aimed at electricians usually print 75°C; charts aimed at homeowners often print 60°C; charts copied from wire manufacturers sometimes print 90°C, which is the number a circuit can almost never use. This chart prints all three and names the rule that picks between them.

Reason 2 — the edition

A different NEC edition. Table 310.16 has changed. A 1999-era reproduction rates 1 AWG copper at 150 amps in the 90°C column where the current table says 145, and 3 AWG at 110 where it now says 115. Charts reproduced from old code books circulate for decades without a date on them. This chart follows NFPA 70-2023, and the copper values were confirmed against a 2023-dated reproduction as well as 2020 and 2017 ones.

Reason 3 — a different table

Solid versus stranded, or a different table entirely. NEC Chapter 9 Table 8 lists conductor resistance separately for solid and stranded conductors, and Table 310.17 gives much higher ampacities for single conductors in free air — 8 AWG copper is 80 amps there against 50 here. A chart quoting free-air ampacity for conductors in a raceway is not wrong so much as answering a different question.

Reason 4 — the cap is missing

A chart that ignores 240.4(D). The most common and most dangerous difference. A chart listing 12 AWG copper at 25 or 30 amps with no cap column is quoting Table 310.16 accurately and still leading a reader to protect that conductor at 25 amps, which the code forbids.

Aluminum Wire Size Chart

Aluminium needs roughly two sizes larger than copper for the same ampacity: 4 AWG aluminium carries 65 amps at 75°C where 4 AWG copper carries 85, and matching copper's 85 amps takes 2 AWG aluminium. The aluminium columns in the chart above are the full picture — there is no separate aluminium table, because NEC Table 310.16 is one table.

Where aluminium earns its place is size and cost. Service entrances, main feeders and long subpanel runs are commonly aluminium, at a fraction of copper's price per foot and about a third of the weight, and above 4/0 the choice is nearly universal. Below 8 AWG it is rare: the NEC permits aluminium branch-circuit conductors no smaller than 12 AWG, and the smaller sizes carry so little current that the saving is not worth the handling.

The termination requirement is the part that gets missed. Every lug, breaker and device an aluminium conductor lands in must be listed for aluminium and marked AL/CU or AL9CU, the stripped conductor wants an antioxidant compound, and the connection needs a torque wrench rather than a screwdriver's judgement. An aluminium conductor in a copper-only lug is a connection that will run hot whatever the chart says. Why the two metals differ is covered on wire sizes explained.

When the Chart Is Not the Final Answer

Voltage drop

Ampacity has no length column, and that is the chart's blind spot. Voltage drop accumulates over the run while the ampacity stays the same, so a conductor that is correct here at 20 feet can be the wrong size at 150 — a 20-amp circuit in 12 AWG copper reaches the 3% target at about 46 feet at 120 volts, and everything past that wants 10 AWG. Beyond roughly 100 feet, check the drop before the wire is ordered. The voltage drop calculator takes the size, the load and the one-way distance and returns the percentage; voltage drop by gauge and run length is proportional to distance, so the 46-foot figure above becomes 92 feet the moment the conductor goes up one size.

Derating

The second is derating. Every figure in this chart assumes 30°C (86°F) ambient and no more than three current-carrying conductors; outside those conditions the ampacity is reduced by ambient temperature correction under NEC 310.15(B) and conductor bundling adjustment under NEC 310.15(C)(1), and where both apply they multiply. An attic in summer and a conduit shared by several circuits are both ordinary installations where the real ampacity is well below the printed one. Both factors apply in a fixed order and multiply: the printed ampacity, then ambient correction, then bundling adjustment. Six current-carrying conductors in a 40°C attic is 0.80 × 0.91 — a little over a quarter off the figure in the table.

Frequently Asked Questions

How many amps can 12 gauge wire handle?

12 AWG copper handles 20 amps. NEC Table 310.16 rates it 25 amps at 75°C and 30 at 90°C, but NEC 240.4(D)(5) caps its overcurrent protection at 20 amps whichever column applies. 12 AWG aluminium is capped at 15 amps.

How many amps can 10 gauge wire handle?

10 AWG copper handles 30 amps. The table rates it 35 amps at 75°C and 40 at 90°C, and NEC 240.4(D)(7) caps it at 30. That makes 10 AWG the standard conductor for a 30-amp dryer or water heater circuit. 10 AWG aluminium is capped at 25 amps.

How many amps can 8 gauge wire handle?

8 AWG copper handles 50 amps on 75°C terminations, 40 amps in the 60°C column and 55 amps at 90°C. NEC 240.4(D) does not reach above 10 AWG, so no separate cap applies — but 8 AWG inside NM-B cable is held to 40 amps by NEC 334.80.

How many amps can 6 gauge wire handle?

6 AWG copper handles 65 amps at 75°C, 55 amps at 60°C and 75 amps at 90°C. 6 AWG aluminium handles 50 amps at 75°C. In practice 6 AWG copper is the conductor used for 50-amp and 60-amp circuits, including ranges and hot tubs.

How many amps can 14 gauge wire handle?

14 AWG copper handles 15 amps. Table 310.16 rates it 20 amps at 75°C, and NEC 240.4(D)(3) caps it at 15 regardless of insulation. It is the smallest conductor permitted for a general-purpose branch circuit, and lighting circuits are where it belongs.

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

8 AWG copper on 75°C terminations, or 6 AWG aluminium. A 50-amp circuit run in NM-B cable needs 6 AWG copper instead, because NEC 334.80 holds that cable to the 60°C column where 8 AWG is 40 amps. The 50-amp wire size page covers the specific cases.

What size wire for a 100 amp service?

4 AWG copper or 2 AWG aluminium for a dwelling service, under NEC 310.12, which permits service and main feeder conductors to be sized at 83% of the rating. A 100-amp *subpanel* feeder is not covered by that allowance and takes 3 AWG copper from Table 310.16. The 100-amp wire size page works through both.

Why does the chart show three different amp ratings for the same wire size?

The chart gives three answers per size because NEC Table 310.16 lists a column for each insulation temperature rating. Read across 12 AWG copper and the row says 20, 25 and 30 amps; which figure applies depends on the lowest-rated termination in that circuit, and the 20-amp breaker cap applies on top of whichever one you land on.

What is the NEC wire size chart?

The NEC wire size chart is Table 310.16, titled "Ampacities of Insulated Conductors Rated Up to and Including 2000 Volts", in NFPA 70. It lists allowable ampacity by conductor size, material and insulation temperature rating, for not more than three current-carrying conductors at 30°C ambient.

Can I use a bigger wire than the chart says?

Yes. Oversizing a conductor is always permitted and is often the right answer on a long run. Two things constrain it: the conductor has to physically fit the breaker or device lug, which is listed for a range of sizes, and a larger conductor takes more room in a raceway, where NEC Chapter 9 fill limits apply.

Ampacity figures on this page are transcribed from NEC Table 310.16 as published in NFPA 70-2023 and verified against three independent reproductions; the maximum breaker column applies NEC 240.4(D) and 240.6(A). They are provided for planning. Conductor sizing affects safety; for anything affecting code compliance, confirm with a licensed electrician and with the NEC edition your jurisdiction has adopted. The code itself is available from the NFPA.

Last updated: September 2026