4 ton AC breaker and wire size
Typical breaker, MCA, MOCP and copper wire reference for a 4 ton residential air conditioner. Equipment nameplate controls.
What this AC breaker and wire reference answers
This 4 ton page is a comparison reference for a common 240 V single-phase residential condenser, not a universal breaker answer. The listed 30.2 A MCA and 45 A maximum overcurrent value are placeholders for screening and must be replaced by the exact rating-plate values. Four-ton systems can expose voltage-drop and feeder-capacity issues on long runs; check the service, disconnect and conductor route as one design.
This page is maintained by the HVAC Calculator Pro Editorial Team. We publish the inputs, calculation basis and limitations so a technician can reproduce the screening result and decide what must be checked in the field. It is a reference aid, not a substitute for the governing code, a licensed designer or the equipment manufacturer's instructions.
Run-length reference
| Run length | Conductor | Action |
|---|---|---|
| up to 60 ft | 8 AWG | typical voltage-drop check |
| 60–100 ft | 8 AWG | ~1.6% drop at MCA (screening) |
| over 100 ft | upsize as calculated | perform voltage-drop calculation |
Calculation trace
At 30.2 A over 100 ft one-way on 8 AWG copper at 240 V, the screening voltage drop is 3.79 V (1.58%). The MCA/MOCP sanity check is conductor ≥ MCA: true, breaker ≤ MOCP: true. This is not a pass/fail code decision; conductor temperature, installation method and local rules still apply.
How to use this 4 ton AC circuit reference
- Photograph the unit rating plate and copy MCA and MOCP exactly.
- Select conductor ampacity using the applicable terminal temperature rating and adjustment factors.
- Check voltage drop, disconnect rating, conduit fill and local amendments before installation.
Worked example: For a 4 ton unit, the first question is not whether the table says 45 A; it is whether the nameplate permits that maximum and whether the conductor is sized for the actual MCA.
Record the result with the project address, equipment model, code edition and assumptions. That audit trail is more useful than copying a single number without its conditions.
Continue with the right tool
Use boundary: This reference cannot see your equipment nameplate, terminal temperature rating, derating, conduit fill, local amendments or electric heat-strip circuit. Read MCA and MOCP from the unit before selecting protection.
Common questions
Can I install the listed breaker on any 4 ton AC?
No. The equipment nameplate and applicable code control. Tonnage alone is not enough to select a breaker or conductor.
What is the difference between MCA and MOCP?
MCA is the minimum circuit ampacity used for conductor sizing. MOCP is the maximum permitted overcurrent device shown by the manufacturer.
Cite or reuse this table
This dataset is free to cite, quote and redistribute with attribution. Use the stable URL below — it does not change when the table is regenerated.
HVAC Calculator Pro. (2026-09-02). 4 Ton AC Breaker Size & Wire Chart. Retrieved from https://hvaccalcpro.com/charts/breaker-size-4-tonhttps://hvaccalcpro.com/charts/breaker-size-4-ton