The documents that frame an Indian installation
Four references come up in most projects, and they do different jobs.
IS 732, Code of Practice for Electrical Wiring Installations. The core standard: circuit arrangement, protection, conductor selection, earthing, inspection and testing. The current edition is IS 732:2019; work to the edition your contract cites, since older versions are still referenced.
IS 3043, Code of Practice for Earthing. Electrode methods — plate, pipe, rod, strip — continuity conductor sizing, resistance measurement and bonding of metallic parts. It decides whether your earthing design is defensible, and it is the clause most often reduced to a note on the drawing.
IS 694, PVC insulated cables up to 1100 V. Construction, insulation thickness and the current ratings manufacturers publish. If you size to a table that does not match the cable you specified, the calculation is decorative.
The National Building Code 2016 and the CEA Safety Regulations. The NBC covers building services including electrical installations; the CEA Measures Relating to Safety and Electric Supply Regulations govern supply and safety obligations. Both matter at approval, not drafting, which is why they get forgotten.
Alongside these sit product standards — IS/IEC 60947 for switchgear, IS/IEC 60898 for MCBs, IS 12640 for RCCBs — and state requirements that vary by jurisdiction.
What actually differs from a European design
| Design item | Indian reference | What to check |
|---|---|---|
| Supply voltage | 230 V single-phase, 400 V three-phase, 50 Hz | Confirm the actual supply at the site; do not assume the nominal |
| Ambient temperature | Manufacturer derating tables, IS 694 ratings | Design ambient is frequently 40 °C or higher; nominal 30 °C tables overstate capacity |
| Cable current rating | IS 694, manufacturer data, IS 732 selection rules | Grouping, conduit fill, buried installation, insulation type |
| Earthing | IS 3043 | Electrode type, soil resistivity, resistance measurement, bonding of metallic services |
| Protection | IS/IEC 60898, IS/IEC 60947, IS 12640 | Breaking capacity at the actual prospective fault level, not a generic 6 kA assumption |
| Residual current | IS 732, IS 12640 | 30 mA protection for socket and wet-area circuits per the current edition |
| Documentation | Contract, IS 732 inspection requirements, NBC | Circuit schedule, cable schedule, earthing layout, test records |
The ambient row causes the quietest errors. A cable rated 24 A in a 30 °C table is rated meaningfully lower at 45 °C in a closed conduit on a terrace in Chennai or Ahmedabad. Use the un-derated figure and the cable is undersized even while the arithmetic looks perfect.
Earthing, handled carefully
IS 3043 is a code of practice, not a single number. It describes acceptable methods and the principles for sizing earthing conductors; the acceptable resistance depends on the system, the supply authority's requirement and the protection settings. Quoting "1 ohm" or "5 ohm" from memory as a code requirement is a shortcut that does not survive scrutiny.
A defensible earthing design contains:
- A stated electrode arrangement — plate, pipe, rod or a combination — with dimensions and material, not a symbol and a note saying "as required".
- Soil resistivity or measured resistance data, or a stated assumption. Seasonal variation matters: a reading taken in dry May is not a wet-July reading.
- Earthing conductor sizing tied to fault current, per the tables and principles in IS 3043.
- Bonding of metallic services — water, gas, structural steel, lift rails — with cross-sections specified.
- A measurement and test plan, because earthing is verified on site, not in the drawing.
Two points recur. Maintenance-free chemical electrodes are common, and the manufacturer's instructions govern depth and backfill. And the earth for a DG set, lift or solar inverter is often separate from the building earth — make that decision explicit, not inherited from the last drawing. IEC 60364's TN/TT/IT vocabulary applies; state the arrangement on the drawing.
Sizing cables for Indian conditions
The method is ordinary: load current, device rating, cable capacity after derating, voltage drop, short-circuit withstand. The Indian specifics sit in the derating and the data source.
Start from the actual cable. Use the manufacturer's rating for that cable — copper or aluminium, PVC or XLPE, in air, in conduit or buried — not a textbook table.
Correct for site temperature, not office temperature. Exposed runs on terraces and in plant rooms should use summer ambient. Confirm factors against the cable standard you use.
Apply grouping and installation factors. Three circuits in one conduit is not one circuit, and a cable in thermal insulation is not a cable clipped to a wall.
Check voltage drop on the real route. Boards are often far from the load — a pump at the rear of a plot, a workshop at the far end — and drop decides the size before ampacity does.
Confirm the breaker's breaking capacity against the prospective fault current at that board. A 6 kA MCB at a much higher fault level is a real defect no ampacity calculation will reveal.
Common domestic sizes — 1.5 mm² lighting, 2.5 mm² sockets, 4 mm² for air-conditioning — are practice, not calculation. They fail on the long run, the high ambient or the upgraded load.
What software should do for an Indian project
A tool built for another market fights the details. What matters:
- Metric conductor sizes in mm² and cable types matching IS 694, not only IEC or NEC ranges.
- 230/400 V, 50 Hz as first-class values, with three-phase balance on the panel.
- Editable derating inputs — ambient, grouping, installation method — with the calculation shown.
- RCD and earthing as modelled objects, so a missing 30 mA device is a finding, not a forgotten note.
- Circuit and cable schedules exportable to XLSX for the estimator.
- PDF and DXF output, because approval still runs on signed drawings.
GorkyCAD covers the plan-to-schedule chain in a browser: import the plan or a PDF survey, build circuits, generate the single-line diagram and panel schedule, run the 41-rule design check, export PDF, DXF, XLSX or IFC. The rule set is built around ПУЭ and ГОСТ, so on an IS 732 project treat findings as engineering prompts and verify the limits against the Indian standard. The demo needs no install.
Honest limits
No IS-specific rule set. The checks are not a substitute for an IS 732 review. Limits, derating factors and earthing requirements must be verified against the Indian standard and utility conditions.
No PLC or control-panel schematics. This covers building electrical design — plans, circuits, boards, calculations, documents. Ladder logic belongs in a dedicated tool.
No offline operation. It runs in a browser and needs a connection; download documents before a site visit.
DWG is not a full editing format. DXF handles 2D exchange; complex DWG with custom objects belongs in a desktop tool.
Calculations depend on your inputs. Ambient, cable data and route lengths are assumptions until you enter real values.
A working sequence
- Confirm the supply: voltage, phases, sanctioned load and, if available, fault level.
- Import the plan, set the scale, verify rooms and wall runs.
- Group circuits by function and location; keep wet areas and heavy loads separate.
- Select cable and protection together, derated for real ambient and installation method.
- Lay out the board; check ways, spare capacity and phase balance.
- Design earthing per IS 3043 with stated electrodes, sizes and bonding.
- Run the checks, resolve structural findings, record accepted exceptions.
- Export drawings and schedules; keep the calculation trail with the issue.
The sequence is universal. The Indian part is steps 1, 4 and 6, where local data replaces defaults — and where a design holds up at approval or comes back with questions.
To try the workflow on a live project, open the demo. Pricing explains the free tier and Pro, and the documentation covers import, export and the calculation inputs. For multi-standard projects, the NEC and IEC in one tool article covers how rule sets switch between jurisdictions.
Sources
- Bureau of Indian Standards — IS 732, Code of Practice for Electrical Wiring Installations: bis.gov.in
- Bureau of Indian Standards — IS 3043, Code of Practice for Earthing: bis.gov.in
- Bureau of Indian Standards — National Building Code of India 2016: bis.gov.in
- Central Electricity Authority — Measures Relating to Safety and Electric Supply Regulations: cea.nic.in
- IEC 60364 series, Low-voltage electrical installations (comparison reference): webstore.iec.ch
Standards are revised; confirm the current edition and any state amendments. This article is engineering background, not legal or professional advice.
IS 732, Code of Practice for Electrical Wiring Installations, is the core wiring standard, supported by IS 3043 for earthing and IS 694 for cables. The National Building Code and CEA regulations apply at approval and supply. Confirm the edition cited in your contract.
No, though they share a framework: protection, conductor selection, earthing, inspection and testing. IS 732 has its own clause structure and local requirements. Never assume an IEC design passes an Indian review unchecked.
It sets out methods and principles rather than one universal ohm value. Acceptable resistance depends on the system, the protection settings and the supply authority's requirement. Measure at the site, state the basis of the design, and verify the applicable clause in the current edition.
Yes. Manufacturer current ratings are usually quoted at a reference ambient, often 30 °C in air. Much of India designs for 40 °C or higher, so a correction factor applies before the cable is compared with the breaker rating. Use the cable manufacturer's table for the specific cable.
It produces plans, circuits, panel schedules, calculations and a rule-based check built on ПУЭ and ГОСТ principles. It does not certify compliance with IS 732 or any standard; a qualified engineer still reviews the design against the Indian standard and local utility conditions.
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