What size wire for a room cooler — and why the breaker is 10 A, not 6 A

PILONE CABLES TECHNICAL TEAM

1.5 mm² copper on a 10 A MCB, three cores so the body is earthed.

A desert cooler draws 200–500 W, which is 0.9–2.3 A on Pakistan's 220 V supply, and 1.5 mm² carries 19.5 A clipped direct at 30°C. Capacity is never the question on this appliance. The two things that are: the fan motor's surge at switch-on, which is why the breaker on this point is 10 A rather than 6 A, and the fact that this is a machine full of water standing in a window.

Small load, awkward circuit

For a room cooler point in Pakistan, run 1.5 mm² copper on a 10 A MCB in three cores: the cooler draws 200–500 W, which is 200 ÷ 220 = 0.9 A to 500 ÷ 220 = 2.3 A, and 1.5 mm² is rated 19.5 A clipped direct at 30°C. The breaker is 10 A rather than 6 A because the fan and pump motors surge at switch-on, and the third core is not optional because the unit holds water and stands where people touch it wet.

Current = watts ÷ 220. Start figure is the rule-of-thumb two to three times running current for a small induction motor — the plate is the authority on your own unit. Cable capacity per BS 7671 reference method C (clipped direct), 30°C ambient, copper, PVC; conductor data per IEC 60228. Verify sizing with a licensed electrician for your installation.
Cooler	Typical power	Running at 220 V	Start, 2–3×	Cable	MCB
Personal / small room	150–250 W	0.7–1.1 A	up to 3.3 A	1.5 mm²	10 A
Standard room cooler	250–400 W	1.1–1.8 A	up to 5.4 A	1.5 mm²	10 A
Large desert cooler with pump	400–500 W	1.8–2.3 A	up to 6.8 A	1.5 mm²	10 A

Read the last row across: 2.3 A running, about 6.8 A for the moment the motor spins up. Put that against the breaker rather than against the cable. 6.8 ÷ 6 = 1.13, so on a 6 A device the surge sits barely over the rating; on a 10 A device it is 0.68 of it and the start is well clear. Where a cooler really does knock its breaker out at switch-on, the number that did it is the locked-rotor current on the plate, not this rule-of-thumb figure — read the plate before changing anything. The cable is untroubled by any of it: at 2.3 A over a 15 m run to a veranda, 1.5 mm² drops 29 × 2.3 × 15 ÷ 1000 = 1.00 V. Going up a cable size does nothing for the start surge; matching the breaker to the motor does.

A room cooler is a wet appliance: it holds several litres, runs a submerged pump, and usually sits on a veranda or in a window opening. Put its circuit behind an RCD and keep the earth continuous to the body. Current capacity also depends on how the cable is installed — derate for conduit, grouping and ambient temperature above 30°C. Have a licensed electrician confirm the size for your load and run length, or start with the cable size calculator.

Running the cooler off a UPS

This is the question load-shedding actually raises, and the cable is not the part that decides it. A 500 W cooler runs at 2.3 A, which a 1000 VA UPS covers easily on paper: 1000 ÷ 220 = 4.5 A of output. The start is what catches it. At two to three times running, the motor asks for about 6.8 A for a moment — half as much again as the unit is rated to give — and a small UPS answers that by alarming or dropping the load rather than by riding it out.

So size the backup on the surge, not on the running figure, and keep the cooler on the same 1.5 mm² point either way. The wiring each side of the inverter is a separate calculation, set out in the UPS and inverter cable size guide.

The cable for this job

Coil of flexible copper cable with black PVC outer sheath

1.5MM² · 2 CORE · 300/500 V · CU CLASS 5

1.5mm 2 Core Flexible Cable

Class 5 stranded copper, 30/0.25, PVC insulated and sheathed, 300/500 V, drawn on the Pilone line in Lahore. Rated 19.5 A clipped direct at 30°C, 29 mV/A/m.

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Cable is priced off the day's copper rate, so we quote per metre and per coil on WhatsApp rather than publish a figure that goes stale. Send the metres and your city.

For a cooler point take the three-core version, so the earth reaches the body: 1.5mm 3 core flexible cable. For a chased conduit run, 1.5mm single core solid cable pulled as separate conductors. All 1.5mm sizes and specs.

Frequently asked

Room cooler ke liye kitne mm ka wire chahiye?

1.5 mm² copper — trade code 3/.029 — 10 A MCB par, aur 3-core lein taake body earth ho jaye. Cooler 200 se 500 W leta hai, yani 220 volt par 0.9 se 2.3 amp. Wire 19.5 A carry karti hai, is liye masla capacity ka nahi — masla start ke waqt ka current hai, aur pani wali cheez hone ki wajah se earthing aur RCD ka hai.

Why does my room cooler trip the breaker when it starts?

The motor — but check the number before blaming the breaker. A 500 W cooler runs at 500 ÷ 220 = 2.3 A, and a start surge of two to three times that is about 6.8 A, only 1.13 times a 6 A MCB and not enough on its own to throw one. The locked-rotor figure on the plate is the number behind a real nuisance trip. A 10 A MCB leaves room for it; the 1.5 mm² cable notices neither.

Does a room cooler need an earth?

Yes, and it is the part most often skipped. The cooler has a metal or part-metal body, holds several litres of water, runs a submerged pump and usually stands on a veranda or in a window where it gets wet. Run the point in three cores so the earth is 1.5 mm² as well, and put the circuit behind an RCD.

Can the cooler share a point with the ceiling fan?

On current, easily: a 500 W cooler at 2.3 A plus a 100 W ceiling fan at 0.45 A is 2.75 A, against 19.5 A of cable. The catch is the start surge — the cooler's 6.8 A kick dips the volts on the shared run and the fan visibly stutters. Keep the cooler on its own way from the board where the board has a spare one.

1.5mm cable for the cooler point, at the factory rate

We draw the copper in Lahore and sell it at the day's rate — no dealer margin, and the line that made the coil answers the message. Tell us the metres and your city: Punjab in 1–2 days, rest of Pakistan in 2–4.

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