Question 1

Which wire size is used for what in house wiring?

Accepted Answer

Typical Indian practice: 1.5 sq mm copper for lights and fans, 2.5 sq mm for general and 16 A sockets, 4 sq mm for ACs, geysers and long heavy-load runs, and 6–10 sq mm for the main supply depending on the connected load. Every circuit is matched to its MCB.

Question 2

Which wire size do I need for a 1.5 ton AC?

Accepted Answer

A typical 1.5 ton split AC draws roughly 7–9 A, so 2.5 sq mm copper on its own circuit with a 16–20 A C-curve MCB is common on a short run. Use 4 sq mm for long runs, 2-ton units or hot routes across a roof. Fit a 16 A socket or a DP switch by the indoor unit, and make sure it's earthed.

Question 3

How much current can 1.5, 2.5 and 4 sq mm wire carry?

Accepted Answer

Reference ratings for PVC-insulated copper in conduit (two loaded conductors, 30 °C) are about 17.5 A for 1.5 sq mm, 24 A for 2.5 sq mm, 32 A for 4 sq mm and 41 A for 6 sq mm. In hot rooms, roofs and crowded conduits the real capacity is lower, so electricians keep a margin.

Question 4

Copper or aluminium wire for a house?

Accepted Answer

Copper for all internal house wiring: it carries more current for its size, bends without cracking and makes reliable connections. Aluminium is used for larger service and distribution cables. Never join copper and aluminium directly — use bimetallic connectors.

Question 5

What do FR, FR-LSH and HFFR mean on wires?

Accepted Answer

FR (flame retardant) insulation resists spreading a fire along the wire. FR-LSH (also written FRLS) adds low smoke and low halogen, so less thick smoke and toxic gas in a fire. HFFR or ZHFR (halogen-free) gives off no halogen gases at all — for places where people must be able to escape through smoke.

Question 6

What are the wire colours for phase, neutral and earth?

Accepted Answer

In India, phase is commonly red (brown in the newer harmonised scheme), neutral black (blue in the newer scheme) and earth green or green-yellow. Three-phase supplies use red, yellow and blue for the three phases. Stick to one scheme throughout a building.

Question 7

How long is a coil of house wire?

Accepted Answer

House wire in India is commonly sold in 90 m coils. Check that the length is printed on the pack and, if in doubt, measure — short coils are a common trick.

Question 8

How can I check if a wire is genuinely the size it claims?

Accepted Answer

Check the printing along the wire (brand, size, standard and voltage), the ISI mark, and count and gauge the copper strands — a genuine 1.5 sq mm wire has noticeably more copper than a 1.0. An electrician can confirm with a micrometer or by measuring the conductor's resistance.

Question 9

Is multi-strand wire better than single-strand?

Accepted Answer

For house wiring, yes. Multi-strand (flexible) wire bends easily, pulls through conduit without kinking and doesn't crack at bends or terminals the way solid wire can. Use proper lugs or ferrules on fine strands in terminals.

Question 10

What's the difference between house wire and flexible cable?

Accepted Answer

House wire is single-core insulated wire meant to run inside conduit or casing. Flexible cables have two or more insulated cores inside an outer sheath — for appliance cords, extension leads and connections that move. Don't run single-core house wire exposed without conduit.

Question 11

Which cable should I use for underground runs?

Accepted Answer

Armoured cable (steel wire or strip armour) buried at a safe depth with warning tape above, or a sheathed cable inside a heavy conduit. Bring it up into a sealed box above ground and protect the circuit with an MCB and RCCB.

Question 12

Which wire size do I need for a 1 HP water pump?

Accepted Answer

A 1 HP single-phase pump draws roughly 5–7 A while running and more at start, so 1.5–2.5 sq mm copper on a short run is common; long runs need a bigger size to limit voltage drop. Submersible pumps use flat cables sized by depth — follow the pump maker's chart.

Question 13

What wire do I need for an EV charger at home?

Accepted Answer

A 7 kW single-phase AC charger draws about 32 A, so it needs its own dedicated circuit — commonly 6 sq mm copper with a 32 A MCB and a suitable RCD, sized for the run length by the installer. Smaller 3.3 kW chargers need about 16 A.

Question 14

Can I join wires inside the wall?

Accepted Answer

Not with twisted-and-taped joints buried in plaster. Make joints only inside accessible junction boxes or switch boxes, using proper connectors or terminal blocks, so they can be inspected and don't loosen and heat up.

Question 15

What is insulation tape for?

Accepted Answer

PVC insulation tape covers and protects small joints and repairs and marks wires by colour. It isn't a substitute for a proper connector: joints should be mechanically sound first, then insulated, and kept inside a box.

Question 16

Why did the insulation on my wire melt?

Accepted Answer

Usually overload (too much current for the wire size), a loose joint or terminal heating up, or a wire run against something hot. Find the cause before replacing the damaged section — and check that the MCB isn't oversized for the wire.

Question 17

What is voltage drop, and when does it matter?

Accepted Answer

Voltage drop is the voltage lost along a wire because of its resistance — it grows with current and length. On long runs to outbuildings, pumps or gates, a too-thin wire leaves appliances starved of voltage; electricians usually keep the drop within about 3–5% by choosing a bigger size.

Question 18

Can TV, internet and power cables share a conduit?

Accepted Answer

Keep them apart. Power cables in the same conduit can cause interference on TV, LAN and phone lines, and it's safer to separate mains from low-voltage cables. Run data and TV cables in their own conduits and boxes.

Question 19

What wire size for the main line from the meter?

Accepted Answer

Commonly 6 sq mm copper for smaller homes and 10 sq mm or more for larger connected loads, matched to the main MCB and the meter rating. Your electrician should calculate it from the total load.

Question 20

What does the voltage rating printed on house wire mean?

Accepted Answer

PVC house wires made to IS 694 are rated for working voltages up to 1100 V, comfortably above 230/415 V household and three-phase supplies. The voltage rating isn't the same as current capacity — that depends on the size.

Question 21

What is a multi-core cable used for?

Accepted Answer

Multi-core cables bundle several insulated conductors in one sheath — 3-core for single-phase with earth, 4-core for three-phase — for appliance supplies, sub-mains, machines and outdoor runs where the cable isn't in conduit.

Question 22

What are flat submersible pump cables?

Accepted Answer

Flat three-core cables designed to hang down a borewell to a submersible pump, with insulation that tolerates water. The size depends on the pump's current and the cable length down the bore — longer runs need a bigger size.

Question 23

Which cable is used for solar panels?

Accepted Answer

Solar (PV) DC cables with UV- and weather-resistant insulation, typically 4 or 6 sq mm, run from the panels to the inverter or charge controller. Ordinary PVC house wire isn't made to sit in sunlight on a roof.

Question 24

How long does house wiring last?

Accepted Answer

Good copper wiring in conduit, not overloaded and not exposed to heat or damp, can last for decades. Many electricians recommend checking older installations closely after about 20–25 years, especially before adding big loads.

Question 25

Can rats and termites damage wiring?

Accepted Answer

Yes — rodents chew insulation and termites can attack wooden casing. Run wires in proper PVC or metal conduit, seal openings around entry points, and avoid wooden battens and casing in damp areas.

Question 26

What do the old '3/22' and '7/20' wire sizes mean?

Accepted Answer

They're older notations giving the number of strands and the wire gauge of each strand. Today house wire is sold by conductor area in sq mm (1, 1.5, 2.5, 4, 6, 10…), which is how current ratings are given — ask for the sq mm size.

Question 27

What is HR (heat-resistant) PVC wire?

Accepted Answer

HR PVC insulation tolerates a higher conductor temperature than general-purpose PVC, which helps in hot locations like near lights, in roof spaces and in crowded conduits. It doesn't make a thin wire safe for a heavy load — the size still matters.

Question 28

Should I buy a wire one size bigger than needed?

Accepted Answer

Often worth it: a bigger size runs cooler, drops less voltage on long runs and leaves room to add loads later. It costs more and needs space in the conduit, so do it for kitchens, AC circuits and long runs rather than every light point.

Question 29

What is the neutral wire for?

Accepted Answer

The neutral completes the circuit, carrying current back from the load to the supply. It's not 'safe' just because it's neutral — a broken or loose neutral can make appliances behave badly and can put dangerous voltages where you don't expect them.

Question 30

What happens if the neutral wire breaks?

Accepted Answer

In a single-phase home, the circuit simply stops. In a three-phase building, a broken shared neutral can push some appliances to very high voltage (burning them) and others to low voltage. Loose neutrals are a common cause of burnt appliances and flickering — get them fixed promptly.