Which wire size does your 1.5-ton AC need?

PILONE CABLES TECHNICAL TEAM · UPDATED 2 OCTOBER 2026

Tonnage alone cannot determine the cable or breaker size for a 1.5-ton AC.

Start with the exact model’s nameplate and installation manual, then check the route, installation method, temperature, grouping and voltage drop. A 2.5 mm² or 4 mm² cable is a candidate only after those checks; neither is a universal recommendation.

Information needed before selecting the cable

Record the model and the manufacturer’s electrical requirements. Cooling tonnage is not electrical input power. Do not substitute a generic running-current or starting-current estimate for the equipment data.

A checklist for the actual AC model and circuit. This table does not prescribe a cable or breaker rating.
Item	What to confirm
AC model	Indoor and outdoor model numbers; inverter or fixed-speed
Electrical supply	Rated voltage, phase and frequency
Design current	Nameplate and manufacturer’s maximum operating/current requirements
Starting behaviour	Equipment data and required protective-device characteristics
Run length	Measured one-way cable route from the supply point
Installation	Conduit, tray, wall insulation, grouping and ambient temperature
Protection	Required device rating/type, breaking capacity and disconnection checks
Earthing	Protective conductor and termination requirements
Cable construction	Material, insulation, core count and permitted installation
Interconnecting cable	Follow the unit’s wiring diagram and manual
Isolation	Follow manufacturer and applicable installation requirements

Use the cable-size calculator to explore a known load and route, then have an electrician verify its assumptions. Missing equipment information should be obtained from the manufacturer before installation.

Comparing cable sizes for the actual installation

A larger cross-section can reduce voltage drop, but choosing by size alone misses the insulation, installation and protection requirements.

Treat 2.5 mm² and 4 mm² as sizes to assess, not as answers attached to a tonnage label.

Sources for the selection method: Schneider Electric: cable sizing and installation conditions; Schneider Electric: protective-device selection. These references explain a process, not a Pilone product rating.

Use the same equipment data and route when comparing candidates. No universal current or run-length rating is assigned here.
Check	2.5 mm² candidate	4 mm² candidate	Decision evidence
Corrected current capacity	Check applicable cable table	Check applicable cable table	Actual method, insulation, loaded cores and correction factors
Voltage drop	Calculate for actual route	Calculate for actual route	Equipment tolerance and total circuit drop
Protection	Coordinate device and cable	Coordinate device and cable	Manufacturer requirements and fault/disconnection checks
Termination	Check conductor compatibility	Check conductor compatibility	Terminal capacity and cable construction

Take 4 mm² if any one of these is true: the cable runs in conduit or is chased into the wall; the run is over 20 m; it shares a conduit with other loaded circuits; the breaker is 20 A; the unit is fixed-speed.
2.5 mm² is defensible only when none of those is true — a short surface run, on its own, on a 16 A breaker.
Never 1.5 mm². At 19.5 A it sits below a 20 A breaker before any derating at all. The cable would fail before the protection did.
Aluminium is the wrong metal here. We sell aluminium cable and it earns its place on service drops and long feeders, at sizes well above this one. At 4 mm², on the small terminals inside an AC isolator, copper is what belongs.

Installation conditions can change the answer

A cable enclosed in a wall or grouped with other loaded circuits does not have the same thermal conditions as one installed in free air.

Select the correct reference installation method first. Apply the documented temperature and grouping corrections for that method; do not apply an arbitrary percentage to a convenient clipped-direct rating.

An electrician should coordinate the design current, protective device and corrected cable capacity, including fault protection. The inverter AC guide is related reading; the exact model’s manual remains essential.

Run length and voltage drop

Measure the one-way route, including rises and bends. Account for upstream voltage drop as well as the final AC circuit.

Route information to collect before a voltage-drop calculation; no maximum permitted length is inferred from tonnage.
Input	Record	Why it matters
Route length	One-way metres	Controls the length-dependent voltage loss
Current	Model-specific design current	Varies between equipment models and conditions
Cable data	Appropriate resistance/reactance or tabulated coefficient	Depends on construction, temperature and circuit
Supply path	Upstream circuit and actual supply conditions	Final-circuit drop is only part of the total
Acceptance limit	Applicable rules and manufacturer tolerance	Must be checked for the installation

A per-amp, per-metre coefficient must match the cable, circuit configuration and calculation basis. Do not double a coefficient that already includes the return path. Use the voltage-drop calculator as a planning aid. Method reference: Schneider Electric: voltage-drop calculations.

1.5 ton AC ke liye kitne mm ka wire chahiye?

Sirf 1.5 ton se wire size tay nahin hota. Model ki nameplate aur manual, cable ka one-way fasla, conduit, garmi aur grouping check karein.

2.5 mm² ya 4 mm² aur breaker ki rating electrician in maloomat ke mutabiq select kare. Model/nameplate aur run ki details bhejein; bina in details ke aik size har AC ke liye theek nahin kaha ja sakta.

When the supply voltage is low

Low supply voltage is a separate condition to investigate. Equipment behaviour depends on its controls and operating limits; assuming constant input watts at every voltage can give a misleading current estimate.

Have the supply and equipment checked against the manufacturer’s limits. Increasing conductor size may reduce circuit voltage loss, but it cannot guarantee an acceptable incoming supply.

Wiring and protection checks

Follow the manufacturer’s supply and interconnection diagram for the exact unit.
Have the electrician select overcurrent protection and any required residual-current protection, including a type compatible with the equipment.
Check protective earthing, isolation, terminal compatibility and fault-disconnection conditions.
Measure the route before ordering and record separate power and interconnecting cable requirements.

Have a licensed electrician verify cable selection, protection and installation for your actual circuit. The cable-size calculator is a planning aid, not an installation approval.

Ordering by strand code or metric size

The strand-code guide explains why 7/29 and 7/36 are not exact metric-size equivalents or current ratings. Specify nominal mm² and construction as well as a trade code.

State these fields separately when asking for cable.
Field	Meaning	Quotation check
Strand code	Count and diameter under a stated convention	Confirm the units
Nominal mm²	Declared conductor size	Match the approved circuit schedule
Core count	Number of conductors within the cable	Match the wiring diagram and earthing arrangement
Construction	Material, conductor class and insulation	Confirm suitability for the route

Once the design is confirmed, compare 4 mm² three-core standard and 4 mm² three-core flexible product entries where appropriate. Verify the selected construction and terminals; these links do not prescribe that size.

How many metres to order for an AC point

Measure each route on the planned installation. A multicore cable is ordered by route length; separate single-core conductors require their individual lengths to be totalled.

Prepare a route schedule rather than a fixed cable quantity for every AC.
Run	Measurement	Specification
Supply to unit / isolator	Measured route plus agreed allowances	Cable and protection approved by electrician
Indoor to outdoor unit	Measured interconnection route	Exact model’s installation manual
Separate protective conductor if required	Its actual route	Designed earthing arrangement

Allow for termination and routing requirements agreed with the installer. A split system may need a separate indoor-to-outdoor cable with a different core count or specification.

Compare cable after the circuit is specified

Two-core standard cable with black outer sheath, cut back to show red and black insulated stranded copper conductors

4 MM² · STANDARD CABLE · CHECK CIRCUIT SUITABILITY

4mm 2 Core Standard Cable

This existing product entry is one option to discuss after the circuit has been designed. Confirm the conductor, insulation, core count and approved size before ordering.

Factory-direct price

Contact for quote

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Send the model/nameplate and cable-run details.

Request the selected construction and measured metres. Confirm availability and delivery with the quotation.

Other constructions include three-core standard and three-core flexible cable. The equipment diagram and installation determine which is suitable.

Frequently asked

1.5 ton AC ke liye kaun sa wire use karen?

Model ki nameplate, manual aur installation ki details se size select hota hai. Sirf tonnage se 2.5 mm², 4 mm² ya breaker ki rating prescribe nahin ki ja sakti.

Is 2.5 mm² enough, or do I need 4 mm²?

Either candidate needs checks for model-specific current, corrected cable capacity, voltage drop, protection and terminations. A short run alone does not establish suitability.

Is 7/29 wire suitable for a 1.5-ton AC?

The code alone cannot answer that. Confirm the nominal size and construction, then assess the circuit. See the strand-code guide.

How many amps does a 1.5-ton AC draw?

Read the exact unit’s nameplate and manual. Cooling capacity does not uniquely determine electrical input current, and models differ.

Which breaker rating and curve should I use?

Follow equipment requirements and have an electrician coordinate overload, fault protection and disconnection with the selected cable. Neither a 16 A nor a 20 A device is universally correct.

Does an inverter AC always need thinner wire?

No. Its maximum electrical requirements and installation conditions must be assessed. Inverter controls do not create a universal cable-size reduction.

Do split and window units need the same cable?

Use the exact model instructions. A split unit may require a separate interconnecting cable; its core count and size are specified by the manufacturer.

How do I get a cable quote?

Send the model/nameplate, one-way route length, installation method, selected specification if available, and delivery city. Confirm the quotation unit and supplied length.

Can the calculator approve my AC wiring?

No. It is a planning tool using stated assumptions. A qualified electrician must confirm the equipment requirements, cable, protection and installation.

Get a quote for your AC cable

Send the model or nameplate, measured run, installation method and delivery city. Include the electrician’s selected cable specification when available.