Electrical work in house construction: a stage-by-stage guide for Karnataka homes

The stages at a glance

Plan the points room by room

Make a point list before the slab work. Changing plans later means chasing walls and patching. A typical starting point for a 2–3 bedroom house:

Plan for things you may add later: a conduit to the terrace for rooftop solar, a spare circuit for an EV charger, and separate meter space if a portion will be rented.

Decide the load and the phase before the slab

The point list tells you how many wires to pull. The load list tells you what connection to apply for, and it has to be settled early because it decides the service cable, the distribution board and the meter board.

• Add up what will be installed: ACs, geyser, induction hob, oven, pumps, and an EV charger if you may buy an electric car. The ESCOM assesses load from what is installed, not from what you expect to run together.
• Above 5 kW, the connection must be three-phase. Two ACs, a geyser and a pump in a three-bedroom house often cross that line. Read single-phase or three-phase before you decide.
• Even on single-phase, build three-phase ready. A 4-core service cable and a DB that can take a four-pole isolator cost little now, and turn a later conversion into a meter change instead of chasing walls.
• Rented floors need their own meters. Plan one meter position per portion, all on the ground floor. Our separate meter guide explains the rules, including the 500 sq m and 25 kW limits above which the building needs its own transformer.

Circuits, wire sizes and breakers

• Use ISI-marked copper wires, FR or FRLS type, from a known brand. Check the length and gauge on the coil.
• Keep lighting, socket and heavy loads (AC, geyser, kitchen) on separate MCB circuits, so one fault does not black out the house.
• Fit a 30 mA RCCB for socket and bathroom circuits. It trips on earth leakage and can save a life.
• Balance three-phase loads across the phases (R, Y, B) in a three-phase house.
• Label every MCB in the DB.

Meter board, service cable and DB location

Where the meter and the main board go is decided at the planning stage, and moving them later means new conduits and a fresh ESCOM visit.

• Meter board at the entrance, at the height and in the space your ESCOM specifies, where the meter reader can reach it without entering the house. Leave room for a smart meter and for a second meter if a portion may be rented later.
• Keep it dry. Not under the drip line of a sunshade or next to a washing area. If it faces the rain, give it a weatherproof box. Water in the meter board is one of the most common monsoon faults.
• Service main cable from the meter to the main DB, sized for the sanctioned load and the length of the run, in its own conduit.
• Main DB near the entrance at a reachable height, not inside a bathroom or store room or above the kitchen platform. Give it spare ways for solar, an EV charger and one more AC.
• Earth pit near the DB, with the earth conductor in its own pipe and the pit chamber left accessible for testing.

The section engineer inspects the meter board and service when you apply. Our permanent connection guide lists the documents and charges for that application.

Kitchen, bathrooms and outdoor points

Most shocks in homes happen where there is water. These areas need more care at the planning stage than any other room.

• Kitchen: keep sockets away from the sink and the stove, above the counter rather than behind the gas cylinder, and give the fridge, mixer, microwave and chimney their own outlets so nothing runs on a multi-plug.
• Bathrooms: place the geyser switch outside the bathroom or well away from the shower, and the geyser point high on the wall with its own earth. Use sealed fittings for lights over the shower area.
• Outdoors: gate lights, garden sockets and the sump or borewell pump need weatherproof boxes, cable in conduit, and a circuit on the 30 mA RCCB. A pump switch fixed on an outside wall at knee height fills with rainwater in the first monsoon.
• Terrace: water tank level controllers, solar and lights on the terrace should all come off a protected circuit, with cable in conduit rather than tied along the parapet.

Slab and wall stage: do not skip these

• Use rigid PVC conduits of adequate size, with bends and junction boxes, not flexible pipe in the slab.
• Seal conduit ends before concreting so slurry does not block them.
• Photograph every slab before casting. It shows you where conduits run for future drilling.
• Keep electrical and plumbing lines apart, and never run conduits through beams without the structural engineer's approval.

Who does the work and who signs for it

• A licensed contractor. Wiring must be done and certified by a licensed electrical contractor. A Class 3 licence covers single-phase work only; a three-phase house needs at least Class 2. Check the licence before you hire: see electrical contractor licence in Karnataka.
• Scope in writing. Agree who supplies materials and which brands, what counts as a point, whether chasing and patching are included, and that the test report is part of the job. Our house wiring cost guide shows how to compare quotations line by line.
• The ESCOM's role. The ESCOM inspects the meter board and service connection. For everything after the meter, it relies on the contractor's signed test report.
• The Electrical Inspectorate. Buildings taller than 15 m, and installations with lifts, need Electrical Inspectorate (CEIG) approval before they are energised. Most individual houses are below this, but a ground + 3 with a lift may not be. See our CEIG drawing approval and inspection guide.

Earthing for a house

A house needs at least two earth pits for the main DB, with more for lightning protection on tall buildings or a separate earth for inverter or solar systems. Dig them while the site is open, near but not under the building, and test the resistance before connecting. See the earthing and testing guide.

Surge protection and future loads

Some things cost little at construction stage and a lot after the paint:

• Surge protection device (SPD) at the main DB. It protects inverter ACs, TVs and routers from surges that come in on the overhead line during storms. For tall or isolated houses, a lightning protection system with its own down conductor and earth has to be designed, not improvised. Read our lightning protection guide.
• Rooftop solar: a conduit from the DB to the terrace, a wall space for the inverter near the DB, and a part of the terrace kept free of water tanks and shade.
• Solar water heater: inlet and outlet pipe routes to the terrace, and a backup heater point if you want one.
• EV charging: a conduit from the DB to the parking, large enough for a heavy cable, even if you only fit a socket now. A 7.4 kW charger alone is above the single-phase limit; see EV charger at home.
• Inverter or UPS: decide which circuits it will back up and wire those separately in the DB, so it never has to carry the geyser or an AC.

Mistakes we fix on new houses

• Switchboards fixed before the furniture plan, so the bed covers the socket and the TV wall has none.
• One circuit for every socket in the house, so a single faulty appliance trips everything.
• A geyser point without its own circuit and earth, sometimes on 1.5 sq mm wire.
• Flexible pipe in the slab that flattened under the concrete, found only when the wire will not pull.
• No earth wire in the socket circuits, or the "earth" connected to a water pipe.
• A meter board placed inside the gate where it cannot be read, or in a corner that floods.
• No spare ways in the DB, so the first new AC means a new board.
• Temporary site wiring left in the walls and plastered over.

Most of these are decided in the first two months of the build, long before the electrician fits a single switch. That is also when the site runs on construction power; our guide to the temporary connection for construction covers the site board and moving to permanent supply without a gap.

Handover checklist

Questions

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