Can I use regular electrical wire for a submersible pump?

No — submersible pump cable has a specific jacket rated for continuous water submersion. Standard NM or THHN wire will degrade and fail underwater.

What happens if wire gauge is too small?

Voltage drop increases, causing the motor to draw more current to compensate, which leads to overheating and premature motor failure.

Does wire gauge affect pump performance even if it eventually starts?

Yes — undersized wire can reduce actual pumping capacity and flow rate even when the pump appears to run normally.

Well Pump Wire Size Chart by Depth & Horsepower (2026)

Why Wire Gauge Matters More With Depth

Every foot of wire adds resistance, and resistance causes voltage drop. A motor that's supposed to receive 230V but is actually getting 210V at the bottom of a deep well will draw more current to compensate, run hotter, and wear out faster — even though everything above ground looks completely normal. This is why wire that's perfectly fine for a 100-foot well can be dangerously undersized for the same pump at 300 feet.

Pump HP	Wire Gauge (up to 100 ft)	Wire Gauge (100-200 ft)	Wire Gauge (200-400 ft)
1/2 HP	14 AWG	12 AWG	10 AWG
3/4 HP	14 AWG	12 AWG	10 AWG
1 HP	12 AWG	10 AWG	8 AWG
1.5 HP	12 AWG	10 AWG	8 AWG
2 HP	10 AWG	8 AWG	6 AWG

These are general guidelines, not a substitute for a proper voltage drop calculation. Actual required gauge depends on your specific voltage, amperage draw, and acceptable drop percentage. Always verify against the pump manufacturer's wire sizing chart or have a licensed electrician calculate it for your exact setup.

Signs Your Existing Wire Is Undersized

Voltage measured at the pressure switch is noticeably lower than at the breaker panel (more than a 5% drop is a concern)
Pump draws higher amperage than its rated nameplate current
Motor runs hot to the touch on the wiring at the wellhead, or trips thermal overload repeatedly

Submersible Pump Wire Specifics

Submersible pump cable is a specific product rated for continuous underwater submersion — not standard THHN or NM cable. It's typically sold as 3-wire (plus ground) jacketed cable rated for direct burial and submersion, and should always be replaced with the same submersible-rated product, upsized in gauge if your depth calculation calls for it.