House Wire Size Guide: 1.5 vs 2.5 vs 4 vs 6 sq mm for Every Room (India 2026)

Short answer: In an Indian home, use 1.5 sq mm copper wire for lights and fans, 2.5 sq mm for ordinary 6A/16A sockets, and 4 sq mm on a dedicated circuit for a split AC or a 3 kW geyser. Go to 6 sq mm for the main feed from the meter, an induction-plus-oven kitchen line, or a 7 kW EV charger. Every heavy appliance gets its own circuit and its own MCB, sized to protect the wire, not the appliance.

Wire is the one part of a home you cannot upgrade later without breaking walls. A few hundred rupees saved by buying a thinner gauge today can mean warm switchboards, tripping breakers and, in the worst case, a fire. This guide explains what each size is for, how to match it to an MCB, and what to check on the coil before you pay.

What "sq mm" actually means

The number on a coil — 1, 1.5, 2.5, 4, 6 — is the cross-sectional area of the copper conductor in square millimetres. It is not the thickness of the insulation and not the diameter. More copper area means the wire can carry more current before it heats up, and it drops less voltage over a long run.

House wire in India is sold under IS 694 (PVC-insulated cables up to 1,100 V). Most coils are 90 m, and most home wiring today uses FR (flame retardant) or FRLS (flame retardant, low smoke) insulation. Multi-strand flexible copper is the norm; solid single-strand is rare in new homes.

Wire size chart for Indian homes

Circuit	Typical load	Wire (copper)	MCB
Lights, ceiling fans, LED strips	Up to ~1 kW per circuit	1.5 sq mm	6A or 10A
Bedroom / living room sockets (6A/16A)	TV, laptop, iron, fridge	2.5 sq mm	16A
Kitchen sockets (mixer, microwave, kettle)	2–3 kW combined	2.5 sq mm, or 4 sq mm on a long run	16A–20A
1–1.5 ton split AC	~1.2–2 kW running, higher at start	2.5 sq mm minimum, 4 sq mm preferred	16A–20A (C curve)
2 ton AC	~2–2.8 kW	4 sq mm	20A–25A
Geyser 2–3 kW	9–13 A	4 sq mm	16A–20A
Induction + oven line	3–4 kW	4–6 sq mm	20A–32A
7 kW EV charger	~32 A	6 sq mm	32A (plus RCCB)
Main feed, meter to distribution board	Whole house	6–10 sq mm (as per sanctioned load)	Main switch / isolator

Treat this as a starting point. The exact current a wire can carry changes with how many wires share one conduit, ambient heat and run length, and every brand publishes its own rating table. For a flat, your electrician should size the main feed from the sanctioned load on your electricity bill.

The one rule that prevents most wiring fires

The MCB protects the wire. A breaker trips when current crosses its rating. If you put a 32A MCB on a 1.5 sq mm line, the wire can overheat long before the breaker ever trips, because the wire's safe limit is far lower than 32 A. So:

• Pick the wire for the load.
• Then pick an MCB at or below what that wire can safely carry.
• Never "fix" a tripping MCB by fitting a bigger one. A tripping breaker is telling you the circuit is overloaded or faulty.

For AC and motor loads, use a C-curve MCB; it tolerates the short start-up surge of a compressor without nuisance trips. A single-pole 16A C-curve unit like this Havells 16A SPN C-curve MCB is the usual pick for a socket or 1.5 ton AC line, and a Schneider Acti9 32A 2-pole C-curve MCB suits a heavier incomer or EV circuit.

Room-by-room: where people go wrong

Lights and fans: 1.5 sq mm is enough

Lighting circuits carry very little current. A room with four LED battens and one BLDC fan draws well under 150 W. 1.5 sq mm is plenty, and going thicker adds cost without benefit. Some builders use 1 sq mm here; it works for pure lighting, but 1.5 sq mm leaves headroom if someone later plugs a heater into a switchboard fed from the light circuit.

A 90 m coil like the Orient Electric Diamond Series 1.5 sq mm copper wire typically covers the lighting points of a 2BHK.

Sockets: 2.5 sq mm, not 1.5

The most common mistake is running 1.5 sq mm to every switchboard, including the 16A sockets. A 16A socket exists to feed an iron, heater or microwave — loads of 1.5–2.5 kW. On 1.5 sq mm wire that pushes the conductor near its limit, especially inside a crowded conduit. Use 2.5 sq mm for every socket circuit.

AC: dedicated circuit, 4 sq mm if the run is long

An AC should never share a circuit with anything else. For a 1–1.5 ton split unit with the distribution board close by, 2.5 sq mm works; if the run is long (upper floor, far bedroom) or you might upgrade to 2 ton later, pull 4 sq mm now. The price difference on one run is small; re-wiring later is not.

Geyser: 4 sq mm and an RCCB upstream

A 3 kW geyser pulls about 13 A continuously for 20–30 minutes. That steady load is what heats undersized wire. Run 4 sq mm on its own MCB, and make sure the bathroom circuits sit behind an RCCB (30 mA) — it trips on earth leakage, which an MCB does not detect. Our home electrical safety guide covers RCCBs and earthing in more detail.

Kitchen: plan for more than you have today

Kitchens gain appliances over the years: air fryer, OTG, dishwasher, induction. Give the kitchen at least two socket circuits on 2.5 sq mm, and a separate 4–6 sq mm line if you plan an induction hob plus oven.

Copper vs aluminium

Use copper for all internal house wiring. Aluminium is cheaper and lighter, which is why power companies use it for overhead lines, but it needs a larger size for the same current, and its joints loosen and oxidise over time at screw terminals. That makes it a poor fit for the many small terminals inside a home.

How to check a coil before you pay

1. ISI mark and IS 694 printed on the coil and repeated along the insulation.
2. Length: a genuine 90 m coil is 90 m. Short coils are a known trick.
3. Strands and copper colour: bright, uniform copper; no dull or blackened strands.
4. FR / FRLS marking on the insulation.
5. Weight: a proper copper coil is noticeably heavy. If a "1.5 sq mm" coil feels light, the conductor may be undersized.
6. Colour code: red / yellow / blue for phase, black for neutral, green or green-yellow for earth. Buying the right colours makes future repairs safer.

How much wire does a home need?

Rough guide for concealed wiring (phase, neutral and earth counted together):

• 1BHK: 3–4 coils of 1.5 sq mm, 2–3 of 2.5 sq mm, 1 of 4 sq mm.
• 2BHK: 5–6 coils of 1.5 sq mm, 3–4 of 2.5 sq mm, 1–2 of 4 sq mm.
• 3BHK: 7–8 coils of 1.5 sq mm, 5–6 of 2.5 sq mm, 2–3 of 4 sq mm.

Layouts vary a lot; ask your electrician for a point-wise estimate before you buy, and buy the colours in the ratio they give you.

Where to save and where not to

Save on the lighting wire brand — any ISI-marked FR copper 1.5 sq mm from a known maker is fine. Save by buying coils during sales; wire prices on Amazon and Flipkart swing noticeably, and we track live electrical deals on our offers page.

Do not save on gauge for AC, geyser and kitchen lines, on the MCB/RCCB, or on earthing. Those three decide whether your wiring is safe for the next 20 years. If you are also replacing switches, our modular switches and sockets guide walks through that side of a rewire.