What size cable for an instant geyser in Pakistan?

PILONE CABLES TECHNICAL TEAM

4 mm² copper on a 25 A MCB for a 4.5 kW instant geyser. 2.5 mm² on a 20 A MCB if the unit is 3 kW.

An instant geyser has no tank to heat slowly, so it puts its whole element on the circuit the moment the tap opens: 4500 W is 20.5 A at 220 V, 3000 W is 13.6 A. 4 mm² carries 36 A clipped direct at 30°C and 2.5 mm² carries 27 A, both measured before derating. The number on the rating plate is what decides between them — not the word "instant".

Instant geyser cable size by kilowatt: 3, 4.5 and 6 kW

Instant and tankless units sold in Pakistan run from about 2000 W on a single-tap kitchen heater to 6 kW on a multi-point unit feeding a shower and a basin. That is a threefold spread in current, which is why one answer cannot cover the category. Read the marking on the unit, then read the row.

Current is the marked wattage divided by Pakistan's 220 V supply. Copper, PVC insulated, two loaded conductors, clipped direct (BS 7671 reference method C) at 30°C; conductor data per IEC 60228. Derate for conduit, grouping and ambient above 30°C — the worked derating example is on the geyser wire size chart.
Marked on the unit	Current at 220 V	Cable (copper)	MCB
2000 W single-tap instant	9.1 A	2.5 mm² (7/.029)	16 A
3000 W / 3 kW instant	13.6 A	2.5 mm² (7/.029)	20 A
4500 W / 4.5 kW instant	20.5 A	4 mm² (7/.036)	25 A
6 kW multi-point instant	27.3 A	6 mm² (7/.044)	32 A
Power selector set below the maximum	Size for the maximum	Size for the maximum	Size for the maximum

An instant geyser in Pakistan takes its cable from the element rating on the plate, not from the type of unit: 3000 W draws 13.6 A at 220 V and runs on 2.5 mm² copper with a 20 A MCB, 4500 W draws 20.5 A and needs 4 mm² with a 25 A MCB, and a 6 kW multi-point unit draws 27.3 A and needs 6 mm² with a 32 A MCB. Those capacities assume copper clipped direct at 30°C ambient with two loaded conductors, per BS 7671 reference method C; a cable bunched in conduit through a hot roof void carries less and moves each row up a size.

The last row is the one that catches people. Several instant units carry a power selector or watt-lock switch that caps the draw at a lower figure, and it is tempting to size the circuit around the setting rather than the element. Do not. Anyone in the house can move that switch, and the day it goes back to maximum the cable and the breaker have to hold the full rating.

Why an instant geyser and a storage geyser take different cable

Both are resistive loads, but they sit at opposite ends of the wattage range. A storage tank has minutes to bring a full load of water up to temperature, so a 2 kW element drawing 9.1 A does the job. An instant unit has to raise the temperature of water while it flows, in seconds, and it buys that with wattage. That is why the same word has two correct answers: a 2 kW storage geyser and a 4.5 kW instant geyser are 9.1 A and 20.5 A, one cable size apart and two MCB ratings apart. The full wattage chart, the 2.5 mm² against 4 mm² argument and the derating arithmetic are on the geyser wire size chart; tank sizes in gallons are in the storage geyser wiring guide.

A built-in ELCB is not the circuit's protection

Instant geysers sold here advertise a built-in ELCB, usually a module moulded into the cord or the plug. It is worth having and it is not the same thing as protecting the circuit. A device sitting at the appliance watches what happens downstream of itself: the element, and the short piece of flex after it. The fixed cable running through the wall from the distribution board is upstream, and nothing in that moulded block is watching it.

So it does not replace a 30 mA RCCB at the board, and it certainly does not replace an earth. The protective conductor has to be continuous from the metal body of the geyser back to the board, which makes the point a three-core job — live, neutral and earth. Two-core cable has no earth conductor in it. Keep the MCB, the RCCB and the isolator outside the wet zone, as in the bathroom wiring guide.

An instant geyser is the highest continuous load in most Pakistani bathrooms and it sits in a wet location. Current capacity depends on how the cable is installed — derate for conduit, grouping and ambient above 30°C. Have a licensed electrician confirm the size, the breaker and the earth for your installation, or start with the cable size calculator.

The cable for this job

Three-core standard cable with PVC outer sheath cut back to show live, neutral and earth conductors of stranded copper

4MM² · 3 CORE · 450/750 V · CU CLASS 2

4mm 3 Core Standard Cable

The size for a 4.5 kW instant unit: live, neutral and earth in one sheath, 7/0.85 stranded copper, PVC insulated and sheathed, 450/750 V, rated 36 A clipped direct at 30°C. Fixed wiring for a wall-mounted instant geyser point, drawn on the Pilone line in Lahore.

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Prices track the daily copper rate. Send the length and your city on WhatsApp for the exact figure.

A 6 kW multi-point unit takes 6mm 3 core cable. A 3 kW single-point unit on a clipped or plastered run takes 7/.029 copper cable pulled as singles with an earth. Also made in 4mm²: 4mm 2 core cable where a protective conductor is already run, and 4mm 3 core flexible cable for the tail off the isolator.

Frequently asked

4500 watt geyser wire size: which cable and which MCB?

4 mm² copper, the size sold as 7/.036, on a 25 A MCB with a Type B curve. A 4500 W element draws 20.5 A at 220 V against a cable capacity of 36 A clipped direct at 30°C. If that cable has to share a bunched conduit in a hot roof void, check the derating before you settle on 4 mm².

Tankless water heater cable size — same as an instant geyser?

The same, because they are the same appliance. Tankless, instant and multi-point all describe a heater with no storage tank, and the cable follows the element rating either way: 3 kW takes 2.5 mm² on a 20 A MCB, 4.5 kW takes 4 mm² on 25 A, 6 kW takes 6 mm² on 32 A.

My instant geyser has a built-in ELCB. Do I still need an RCCB in the board?

Yes. A built-in ELCB protects what is downstream of it, which is the element and its flex. The fixed cable in the wall between the distribution board and the geyser is upstream of that device and is not covered by it. A 30 mA RCCB at the board covers the whole circuit, and neither device is a substitute for a continuous earth.

Can I run an instant geyser off a 3-pin socket?

Not above 2 kW, and it is a poor idea below it. A 4.5 kW unit draws 20.5 A, which is beyond what a general socket point and its shared circuit are built for. An instant geyser wants its own cable from the board, its own MCB sized to the element, and an isolator outside the wet zone.

What about a semi-instant geyser?

A semi-instant unit has a small tank and a large element, so it usually sits between the two bands. Ignore the name and read the plate: 2000 W is 9.1 A on 2.5 mm² and a 16 A MCB, 3000 W is 13.6 A on 2.5 mm² and 20 A, 4500 W is 20.5 A on 4 mm² and 25 A.

4mm and 6mm cable for the instant geyser point, at the factory rate

We draw the copper in Lahore and sell it at the day's rate — no dealer margin. Send the wattage off the rating plate, the length and your city: Punjab in 1–2 days, rest of Pakistan in 2–4.

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