What size wire for an oil heater — and why the extension board is the weak point

PILONE CABLES TECHNICAL TEAM

2.5 mm² copper on a 16 A MCB — the wire the trade sells as 7/29.

An oil-filled radiator draws 1500–2500 W, which is 6.8–11.4 A on Pakistan's 220 V supply, and 2.5 mm² carries 27 A clipped direct at 30°C. The point in the wall is not the part that fails on this appliance. The extension board it gets plugged into is, because the heater holds that current for hours at a time.

A heavy load on a plug-in appliance

For an oil heater in Pakistan, run the socket point in 2.5 mm² copper on a 16 A MCB, three cores so the earth reaches the metal body: the heater draws 1500–2500 W, which is 1500 ÷ 220 = 6.8 A to 2500 ÷ 220 = 11.4 A, and 2.5 mm² is rated 27 A clipped direct at 30°C. Read the rating plate rather than the number of fins — fin count is a size, not a wattage.

Current = watts ÷ 220. Point cable is the fixed run from the board to the socket. Capacity per BS 7671 reference method C (clipped direct), 30°C ambient, two loaded conductors, copper, PVC; stranding per IEC 60228. Wattages are typical plate figures — read your own. Verify sizing with a licensed electrician for your installation.
Heater setting	Current at 220 V	Point cable	Trade code	MCB
1000 W, low	4.5 A	2.5 mm²	7/.029	16 A
1500 W	6.8 A	2.5 mm²	7/.029	16 A
2000 W	9.1 A	2.5 mm²	7/.029	16 A
2500 W, full	11.4 A	2.5 mm²	7/.029	16 A
Two 2000 W heaters, one circuit	18.2 A	4 mm²	7/.036	20 A

Length is not the constraint here: at 11.4 A over a 12 m run, 2.5 mm² drops 18 × 11.4 × 12 ÷ 1000 = 2.46 V. Hold the installation to 3% of 220 V — 6.6 V — and give the final circuit half of it, 3.3 V, since the submain has spent the rest. 2.46 V is inside that budget. The last row is the one that catches people out — two heaters on one room circuit is 18.2 A, past a 16 A breaker before the cable has warmed up.

Kya oil heater extension board par chal sakta hai?

A common extension board is made in 0.75 mm², rated 6 A, and it drops 62 mV per amp per metre. Put a 2000 W heater on it and the lead carries 9.1 A — half as much again as it is rated for — for as long as the room is cold. Over a 5 m lead that is 62 × 9.1 × 5 ÷ 1000 = 2.82 V lost inside the lead, and those volts come out as heat in the coil nobody unwinds. The same 5 m in 1.5 mm², rated 19.5 A, loses 29 × 9.1 × 5 ÷ 1000 = 1.32 V and stays inside its rating.

Oil heater ko patlay extension board par na chalayen. Heater ko deewar ke socket se seedha lagayen; agar wire nahi pohanchti to hal doosra socket hai, lamba lead nahi.

Current capacity depends on how the cable is installed. Derate for conduit, grouping, and ambient temperature above 30°C. An oil heater is a continuous load with a metal body, so keep the earth core continuous and do not run it through a coiled lead. Have a licensed electrician confirm the size for your load and run length — or start with the cable size calculator.

The cable for this job

Three-core flexible cable with outer sheath cut back to show stranded copper conductors

2.5MM² · 3 CORE · 300/500 V · CU CLASS 5

2.5mm 3 Core Flexible Cable

Class 5 stranded copper, 50/0.25, PVC insulated and sheathed, drawn on the Pilone line in Lahore. Rated 24 A on three loaded cores, 18 mV/A/m. Three cores so the earth matches the live and neutral.

Factory-direct price

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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.

Where the earth is run separately, 2.5mm 2 core flexible cable. For two heaters on one circuit, step up to 4mm 3 core cable.

Frequently asked

Oil heater ke liye kitne mm ka wire chahiye?

2.5 mm² copper — trade code 7/.029 — 16 A MCB par, aur 3-core lein taake body earth ho jaye. Oil heater 1500 se 2500 W leta hai, yani 220 volt par 6.8 se 11.4 amp, aur yeh load ghanton chalta rehta hai. Wire 27 A carry karti hai, is liye point ki capacity kaafi hai.

Kya main oil heater extension board par chala sakta hoon?

Behtar nahi. Aam extension board 0.75 mm² ka hota hai, jiski capacity sirf 6 A hai, jabke 2000 W heater 9.1 A kheenchta hai — rating se dedh guna zyada, wo bhi ghanton tak. 5 metre ke lead mein 62 × 9.1 × 5 ÷ 1000 = 2.82 V khud lead kha jata hai. Heater ko deewar ke socket se seedha chalayen.

Is 1.5mm wire enough for an oil heater?

For one heater on a short point, the numbers work: 1.5 mm² carries 19.5 A and a 2500 W heater draws 11.4 A. It is the wrong choice anyway, because a room socket rarely feeds one appliance for its whole life. Wire the point in 2.5 mm² and the circuit still has margin when a second heater or an iron joins it.

Does an oil heater need its own circuit?

One heater does not. It plugs into an ordinary 16 A socket circuit and takes 6.8–11.4 A of it. Two do: 2000 W each is 18.2 A together, past a 16 A MCB. Either put the second heater on a different circuit, or run that circuit in 4 mm² on a 20 A breaker from the board.

2.5mm cable for the heater 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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