REFERENCE · JULY 2026
For submersible borewell drops, use submersible cable specifically rated for water immersion — typically IS 694:2010 flat 3-core / 4-core with a special PVC sheath, or IS 9968 rubber-sheathed cable for deep-set drops.
For agricultural and rural single-phase pumps, plain FR per IS 694:2010 remains standard. Switch to FR-LSH for any pumpset feeding from a basement that NBC 2016 Part 4 categorises as a smoke-zone risk.
Listed alphabetically. Verify the BIS standard mark and CM/L licence on the jacket at bis.gov.in.
Wire for Pump — Submersible / Borewell / Mono-block — Size by HP
For a 1 HP single-phase submersible drawing approximately 8 A continuous on 230 V, the canonical recommendation is 3-core flat 2.5 sqmm Class 5 copper, FR per IS 694:2010 (submersible variant), sized to IS 3961:2024 ampacity tables and the NBC 2016 Part 8 §3.4 voltage-drop cap of 5 % for sub-mains and 3 % for final circuits. For 5 HP and 7.5 HP three-phase borewell pumps, step up to 4-core flat 4 sqmm or 6 sqmm copper per IS 9968 / IS 694:2010. This page is a third-party comparison reference.
The Sizing Table — HP to Cable
| Pump | Type | Phase | Continuous Amps | Recommended MCB / Starter | Recommended Cable | Flame / Standard |
|---|---|---|---|---|---|---|
| 0.5 HP | Monoblock / submersible | 1Ø 230 V | 4 A | 6 A | 1.5 sqmm 3-core flat Cu | FR / IS 694:2010 |
| 1.0 HP | Submersible | 1Ø 230 V | 8 A | 10 A | 2.5 sqmm 3-core flat Cu | FR / IS 694:2010 (sub) |
| 1.5 HP | Submersible | 1Ø 230 V | 12 A | 16 A | 2.5 sqmm 3-core flat Cu | FR / IS 694:2010 (sub) |
| 2.0 HP | Submersible | 1Ø 230 V | 16 A | 20 A | 4 sqmm 3-core flat Cu | FR / IS 694:2010 (sub) |
| 3.0 HP | Borewell | 3Ø 415 V | 5–6 A/phase | TPN 16 A | 4-core 2.5 sqmm flat Cu | FR / IS 694 or IS 9968 |
| 5.0 HP | Borewell | 3Ø 415 V | 8–9 A/phase | TPN 16 A DOL | 4-core 2.5 sqmm flat Cu | FR / IS 9968 |
| 7.5 HP | Borewell | 3Ø 415 V | 12–14 A/phase | TPN 25 A SD | 4-core 4 sqmm flat Cu | FR / IS 9968 |
| 10 HP | Borewell | 3Ø 415 V | 16–18 A/phase | TPN 32 A SD | 4-core 6 sqmm flat Cu | FR / IS 9968 |
| 15 HP | Industrial | 3Ø 415 V | 24–27 A/phase | TPN 40 A SD | 4-core 10 sqmm armoured | IS 1554 Pt 1 FR |
Decision Tree — Load × Length × Ambient × Flame
- HP to amps. 1Ø: A ≈ HP × 6 (PF 0.8); 3Ø: A ≈ HP × 1.7 (PF 0.85). Always cross-check the motor nameplate and the SF (service factor).
- Apply IS 3961:2024 ampacity for buried / in-conduit / in-water installation. Submerged cable carries higher ampacity than air because water cools the conductor.
- Voltage drop is the binding constraint for borewell drops. NBC 2016 Part 8 §3.4 caps total drop at 5 % for sub-mains; pump motors stall below 90 % rated voltage. For a 5 HP pump at 50 m drop on 4 sqmm Cu, drop is ~3.2 % — within limit; on 2.5 sqmm it exceeds 5 %.
- Apply ambient + grouping derating. For deep-water installation (under 30 °C) no derating. For surface-installed monoblocks in a hot pump room (45 °C) derate by ~0.87 per IS 3961:2024 Table 5.
- Choose the right cable construction. Submersible drop-cable per IS 694:2010 (PVC, flat-3-core or flat-4-core) for borewells; round flexible per IS 694:2010 for monoblocks; IS 1554 Pt 1 armoured for trenched runs to outdoor pumphouses.
Use /tools/cable-size-calculator for a numeric voltage-drop check; refer to /learn/is-3961-ampacity-chart for derating factors.
Flame-Grade Selection (NBC 2016 Part 4)
| Pump Location | Standard | Recommended Grade |
|---|---|---|
| Borewell drop (in water) | IS 694:2010 / IS 9968 | FR PVC submersible (flame grade rarely tested in water) |
| Pump room — G+3 building | IS 694:2010 | FR |
| Pump room — G+4 / commercial / hospital basement | IS 694:2010 / IS 17048:2018 | FR-LSH or HFFR |
| Outdoor trenched run to pumphouse | IS 1554 Pt 1 | FR Armoured PVC |
| Industrial pumphouse / petrochem | IS 17048:2018 | HFFR + armoured |
Brand Options — 3-core flat 2.5 sqmm Cu Submersible (1 HP / 1.5 HP)
| Brand | SKU example | Pack | Price |
|---|---|---|---|
| Finolex | 3-core 2.5 sqmm flat submersible | 100 m | See live price |
| Havells | Flat submersible 3C × 2.5 sqmm | 100 m | See live price |
| KEI | Submersible flat 3-core 2.5 sqmm | 100 m | See live price |
| National Cables | 3C 2.5 sqmm flat submersible | 100 m | See live price |
| Polycab | Submersible flat 3C 2.5 sqmm | 100 m | See live price |
| RR Kabel | 3-core 2.5 sqmm submersible flat | 100 m | See live price |
Common Mistakes — Pump Wiring
- Using ordinary house wire for a borewell drop. Submersible drop-cable per IS 694:2010 (flat 3-core) is mandatory — round single-cores fail at depth due to water ingress.
- Sizing on ampacity alone. For borewell drops the voltage-drop limit (NBC 2016 Part 8 §3.4) is the binding constraint, not IS 3961:2024 ampacity.
- Skipping the starter / no DOL or SD. Pumps over 3 HP require Star-Delta or soft-starter to limit LRA — direct-on-line stresses the cable.
- Ignoring grouping derating when multiple pump circuits share a single cable tray at the pumpset panel.
- Using non-water-resistant flex for submersible installations. A regular Class 5 round flexible IS 694 cable is not acceptable for in-water drops; use the dedicated 3-core flat submersible variant.
Frequently asked questions
What wire for a 1 HP submersible pump?
3-core flat 2.5 sqmm Class 5 copper, submersible-grade per IS 694:2010, on a 10 A MCB. The 8 A continuous current sits well inside the IS 3961:2024 ampacity, with NBC 2016 voltage-drop margin for drops up to ~30 m.
What is the cable size for a 5 HP borewell pump?
4-core flat 2.5 sqmm copper for short drops up to ~30 m; 4-core flat 4 sqmm for drops up to ~60 m. Sizing is voltage-drop limited per NBC 2016 Part 8 §3.4 (5 % cap) — IS 3961:2024 ampacity alone would suggest a smaller cable.
Is 2.5 sqmm enough for a 1 HP pump?
Yes, on dedicated 10 A MCB for runs under ~30 m. The IS 3961:2024 base ampacity of 2.5 sqmm copper is 23 A — far above the 8 A draw — and voltage drop stays within the NBC 2016 3 % limit.
What cable for a 1.5 HP submersible?
3-core flat 2.5 sqmm copper submersible per IS 694:2010 on a 16 A MCB. At 12 A continuous the conductor is under 55 % of its IS 3961:2024 ampacity, leaving voltage-drop margin for ~40 m drops.
What is the difference between submersible cable and ordinary house wire?
Submersible cable per IS 694:2010 (flat construction, water-resistant PVC sheath) or IS 9968 (rubber sheath) is rated for continuous immersion. Ordinary IS 694:2010 round flexible house wire is not rated for water and the conductor will corrode within months at depth.
Should I use 3-core or 4-core cable for a borewell pump?
3-core (R-Y-B / phase-neutral-earth) for single-phase pumps; 4-core (R-Y-B-E or 3-phase + earth) for three-phase pumps. Both are flat construction so they fit alongside the riser pipe.
What is the IS standard for submersible pump cable?
IS 694:2010 covers PVC-sheathed submersible cable for typical Indian borewell drops. IS 9968 covers EPR / rubber-sheathed flexible cables for heavier-duty industrial submersible motors.
How does cable length affect pump cable sizing?
Pump motors stall below 90 % of rated voltage, so NBC 2016 Part 8 §3.4 caps total drop at 5 %. Every metre of borewell drop adds resistance — a 5 HP pump at 80 m drop typically needs 6 sqmm Cu even though the ampacity would allow 2.5 sqmm.
Should pump cable be FR or FR-LSH?
FR per IS 694:2010 for the underwater drop. For the pump room and surface wiring, FR is sufficient in G+3 buildings; NBC 2016 Part 4 mandates FR-LSH from G+4 upwards.
Class 2 or Class 5 conductor for pump cable?
Class 5 (flexible) per IS 8130:2013 is standard for submersible drops because the cable must coil during installation. Class 2 stranded is used for fixed surface wiring to monoblocks.
What MCB size for a 1 HP pump?
10 A C-curve MCB for the 8 A continuous draw and 30 mA RCBO for shock protection per NBC 2016 Part 8. Pumps have inrush so a C-curve trip is preferred over a B-curve.
How do I verify the submersible cable is BIS-certified?
The flat jacket must print "ISI", "IS 694:2010", manufacturer name, and a CM/L licence number every metre. Cross-check the CM/L at bis.gov.in/standard-mark-licence before lowering the cable into the borewell.
METHODOLOGY
Updated weekly by the cablepriceindia.com price-research desk. Last verified: 17 July 2026. Sources cited inline. We are an independent price-discovery service. Verify any BIS Conformity Marking Licence (CM/L) at bis.gov.in.