Wire and Circuit Breaker Capacity Table

Ampere Rating Wire Copper Capacity Table

AWG Size	Metric (MM²)	THW Ampacity (75°C Maximum Operating Temperature)	THHN Ampacity (90°C Maximum Operating Temperature)	Breaker Capacity	Load Allowed (80%)
14	2.08	20	25	15A	12A
12	3.31	25	30	20A	16A
10	5.26	35	40	30A	24A
8	8.37	50	55	50A	40A
6	13.30	65	75	65A	52A
4	21.20	85	95	85A	68A
3	26.70	100	115	100A	80A
2	33.60	115	130	125A	100A
1	42.40	130	150	150A	120A
1/0	53.50	150	170	175A	140A
2/0	67.40	175	195	200A	160A
3/0	85.00	200	225	225A	180A
4/0	107.20	230	260	250A	200A
250 kcmil	127.00	255	290	300A	240A
300 kcmil	152.00	285	320	350A	280A
350 kcmil	177.00	310	350	400A	320A
400 kcmil	203.00	335	380	450A	360A
500 kcmil	253.00	380	430	500A	400A
600 kcmil	304.00	420	475	600A	480A
700 kcmil	355.00	460	520	700A	560A
750 kcmil	380.00	475	535	750A	600A
800 kcmil	405.00	490	555	800A	640A
900 kcmil	456.00	520	585	900A	720A
1000 kcmil	507.00	545	615	1000A	800A

AWG Size:
- American Wire Gauge, a standard for wire diameters.
- Smaller numbers mean thicker wires.
Metric (MM²):
- The cross-sectional area of the wire in square millimeters.
- Cross-sectional area in metric units, useful for international applications.
THW Ampacity (75°C):
- Applications: Dry and Wet Locations.
- The current carrying capacity of copper wire with THW (Thermoplastic Heat and Water resistant) insulation at 75°C.
THHN Ampacity (90°C):
- Applications: Dry and Damp Locations.
- The current carrying capacity of copper wire with THHN (Thermoplastic High Heat-resistant Nylon-coated) insulation at 90°C.
Breaker Capacity:
- The typical breaker size for the given wire size.
- The recommended breaker size for protecting the wire.
Load Allowed (80%):
- The maximum recommended continuous load on the circuit, calculated as 80% of the breaker capacity, in accordance with PEC guidelines.
- The safe continuous load limit ensures the circuit does not overheat.

Explanation of the Ampere Rating Wire Copper Capacity Table

The table provided gives a comprehensive overview of the current-carrying capacity, or ampacity, of copper wires of different sizes, measured in American Wire Gauge (AWG) and their equivalent in square millimeters (MM²). It also provides ampacity ratings for wires with THW and THHN insulation types, the recommended breaker sizes, and the allowed continuous load for each wire size. Here’s a detailed explanation of each column and its significance:

Columns and Their Meanings:

AWG Size:
- Definition:
  American Wire Gauge (AWG) is a standard way of denoting wire diameter. Smaller AWG numbers indicate thicker wires.
- Example:
  14 AWG is thinner than 10 AWG.
Metric (MM²):
- Definition:
  This column represents the cross-sectional area of the wire in square millimeters, a metric measurement equivalent to AWG.
- Example:
  14 AWG is approximately 2.08 mm².
THW Ampacity (75°C):
- Definition:
  The maximum current (in amperes) that a wire with THW (Thermoplastic Heat and Water resistant) insulation can safely carry at 75°C ambient temperature.
- Example:
  A 14 AWG wire with THW insulation can carry 20 amperes.
THHN Ampacity (90°C):
- Definition:
  The maximum current a wire with THHN (Thermoplastic High Heat-resistant Nylon-coated) insulation can carry at 90°C ambient temperature.
- Example:
  A 14 AWG wire with THHN insulation can carry 25 amperes.
Breaker Capacity:
- Definition:
  The recommended size of the circuit breaker that should be used to protect the wire. This ensures the wire does not overheat and cause a fire.
- Example:
  For a 14 AWG wire, a 15-ampere breaker is recommended.
Load Allowed (80%):
- Definition:
  To ensure safety and reliability, continuous loads on a circuit should not exceed 80% of the breaker’s capacity. This column lists the maximum allowed continuous load for each breaker.
- Example:
  For a 15-ampere breaker, the maximum continuous load is 12 amperes (80% of 15A).

Usage Considerations:

Ampacity:
- This indicates the maximum current a wire can handle before overheating. THHN has a higher ampacity than THW due to its higher temperature rating.
Breaker Capacity:
- Electrical codes recommend using a breaker that is appropriately rated for the wire size to prevent overheating and potential fire hazards.
Load Allowed:
- Continuous loads should not exceed 80% of the breaker capacity to ensure safety and longevity of the electrical system.

Practical Application:

Wire Sizing for Circuits:
- When planning electrical circuits, choose the wire gauge based on the expected load and distance to prevent voltage drop and overheating.
- Purpose:
  Selecting the correct wire size ensures that the wire can handle the expected electrical load without overheating.
- Example:
  If a circuit requires carrying 24 amperes, you should choose a wire gauge that supports this current. According to the table, a 10 AWG wire with THHN insulation is suitable.
Breaker Selection:
- Ensure the breaker is rated appropriately for the wire gauge to protect the circuit from overcurrent conditions.
- Purpose:
  A properly sized breaker protects the wire and prevents potential fire hazards by interrupting the circuit if the current exceeds safe levels.
- Example:
  For a 10 AWG wire, a 30-ampere breaker is recommended.
Load Management:
- Purpose:
  To prevent overloading the circuit, ensure that continuous loads do not exceed 80% of the breaker’s capacity. This margin helps avoid overheating and ensures the longevity of the electrical system.
- Example:
  For a 30-ampere breaker, the continuous load should not exceed 24 amperes.
Compliance with Codes:
Adhering to the Philippine Electrical Code (PEC) is crucial for safety and legal compliance.

IMPORTANT NOTICE:

Before taking any actions in your Electrical Installations if you are unsure or not qualified or trained to do Electrical works always consult a Licensed Electrical Practitioner, Professional Electrical Engineer (PEE), Registered Electrical Engineer (REE), or Registered Master Electrician (RME).