Fuse or Circuit Breaker Size

Minimum Wire Size

Copper Conductor

Aluminum Conductor

15 amps

14

n/a

20 amps

n/a

n/a

30 amps

10

8

40 amps

8

6

50 amps

6

4

Copper

Aluminum

Service Rating

4 AWG

2 AWG

100 amps

1 AWG

2/0

150 amps

2/0

4/0

200 amps

Home
TRIPLE M LLC
Contact Us
Realitors
Downloads
Links
Inspections
Diagrams
Construction
About Us
Articles
Return To Electrical Diagrams
Wire Size to Ampage Rating
Electrical Safety Article
Branch Circuit Wires
Branch circuit wires, also referred to as circuit conductors, have their ampacity (amount of load they can carry) determined by their gauge size (AWG). Wiring is typically referred to as 12/2, 10/2, 12/3 and so on. The first number is the gauge size and the second is the number of conductor wires.
Grounded Conductor / Neutral wire
Ungrounded Conductor / Hot wire
Bare Conductor / Ground wire
Wire Gauge
# of Conductors
With Ground
Sheathing Type
Note on the Conductor wire number: the ground wire is never counted, hence a 12/2 wire would have 2 conductor wires and one ground wire. 12/2 wire is the most common wire size used in residential homes today. 3 conductor (x/3) wire is needed when a second hot wire is required; like for a 220v appliance or a 3-way switch
The table Below gives the ampage rating (breaker size) to the wire size (conductor):
The table Below gives the ampage rating to the wire size for service cable:
Service Wires