Hot Tub / Spa (50A, 240V) Wire Gauge — NEC 2023 Sizing Guide
Dedicated 50A 240V circuit for portable spa or hot tub. Use 8 AWG copper. 50A at 60 ft on 240V: 1.95% voltage drop.
8 AWG
copper conductor
1.95%
voltage drop
50A
ampacity
▸ Advanced options — derating, breaker & conduit
8 AWGcopper
Ampacity OKVD 1.95%
8 AWG selected by ampacity (50A ≥ 50A).
50A
Ampacity
at 75°C
1.95%
Voltage drop
4.69V
235.3V
At load
receiving end
16,510
Circular mils
8.37 mm²
Min for ampacity ← governs
8 AWG
16,510 CM
Min for ≤3% VD
8 AWG
16,510 CM
50A
Breaker size
NEC 240.6(A)
~$138
Wire cost est.
120 ft THHN
1" EMT
Conduit size
3 conductors
10 AWG Cu
Ground wire (EGC)
NEC 250.122
229.3W
Power loss
~$281.22/yr
Copper vs Aluminum (for 50A at 60 ft on 240V)
Copper
8 AWG
VD: 2.0% · 8.37 mm²
Aluminum
6 AWG
VD: 2.0% · 13.3 mm²
Hot Tub / Spa (50A, 240V)
Dedicated 50A 240V circuit for portable spa or hot tub.
For a 50A load at 60 ft on 240V, use 8 AWG copper.
NEC 680.42 — must be GFCI protected, run buried conduit
Required wire gauge
Ampacity governs
8 AWG copper
50A ampacity | 1.95% voltage drop | 240V system
Circuit specifications
NEC 2023 compliant. Min wire for ampacity: 8 AWG. Min wire for 3% VD: 8 AWG.
Preset distance sensitivity
How Hot Tub / Spa (50A, 240V) sizing changes as one-way run distance changes.
Installation planning checklist
Checklist values are generated from the preset and must be confirmed against the actual equipment and local code before installation.
Copper vs aluminum preset alternatives
Preset alternatives keep the same load, voltage, distance, and voltage-drop target while changing conductor material.
Preset assumptions
This preset models 50A, 240V single-phase, 60 ft one-way, copper conductor, 75C temperature rating, and 3% maximum voltage drop.
Presets are planning shortcuts for common search intents. The equipment nameplate, MCA/MOCP values, continuous-load status, conductor count, ambient temperature, and local amendments can change the final answer.
Common use: NEC 680.42 — must be GFCI protected, run buried conduit
Safety and code review notes
Confirm breaker size, conductor insulation, terminal temperature rating, grounding conductor, raceway fill, GFCI/AFCI rules, and wet-location requirements before installation.
For EV chargers, HVAC equipment, motors, spas, detached structures, and service feeders, nameplate and local-code rules can override a generic ampacity calculation.
This preset passes the modeled ampacity and voltage-drop checks under its stated assumptions.
Wire sizing derivation
Load: 50A at 240V (single-phase), 60 ft, copper at 75°C
Step 1 — Ampacity: find smallest wire where derated ampacity ≥ 50A → 8 AWG (base 50A, no derating)
Step 2 — Voltage drop: allowed VD = 240V × 3% = 7.199999999999999V
CM = (2 × 12.9 × 50A × 60ft) / 7.199999999999999V = 10,751 CM → 8 AWG
Step 3 — Recommended: 8 AWG (ampacity governs)
Breaker: NEC 240.6(A): use 50A breaker (next standard size ≥ 50A)
Ground wire: NEC Table 250.122: 50A OCPD → EGC ≥ 10 AWG Cu (or 8 AWG Al)
Power loss: 229.3W in run — ~2008.7 kWh/yr (~$281.22/yr @ $0.14/kWh)
Cost: ~$1.15/ft × 120 ft = ~$138 (2024 retail THHN)
Conduit: minimum 1" EMT for 3 conductors of 8 AWG
Verification: 50A ≥ 50A ✓ | VD 1.95% ≤ 3% ✓
Other common circuits
Kitchen Outlet Circuit (20A, 120V)10 AWG copper20A • 120V • 50ftElectric Dryer (30A, 240V)10 AWG copper30A • 240V • 25ftEV Charger Level 2 (50A, 240V)8 AWG copper50A • 240V • 50ftElectric Range / Oven (50A, 240V)6 AWG copper50A • 240V • 25ftSubpanel Feeder (100A, 240V)1 AWG aluminum100A • 240V • 75ftWorkshop Tool Circuit (30A, 240V)10 AWG copper30A • 240V • 75ft