A 240 V hot tub or spa needs a dedicated GFCI-protected circuit — most are 50 A or 60 A, four-wire (two hots, neutral, ground). NEC Article 680 adds three things a normal circuit doesn't: a GFCI on all spa outlets (680.44), a maintenance disconnect within sight and at least 5 feet from the water (680.13), and equipotential bonding with a solid #8 copper wire tying the metal parts together (680.26). Follow the spa's manual for the wire size — it often specifies 6 AWG copper, which can be stricter than the code table.
Wiring a spa? The hot tub wiring calculator sizes the circuit and walks the Article 680 chain — GFCI, disconnect, bonding, and burial depth — free, no signup. This guide explains the safety rules that make spa wiring different from any other circuit.
🔌 The circuit: 50–60 A, GFCI, dedicated
Most 240 V spas run on a 50 A or 60 A dedicated circuit; larger three-pump models use 60 A, smaller ones 30–40 A. It's a four-wire circuit (two hots, a neutral, and an equipment ground), and the whole circuit must be GFCI-protected (680.44) — almost always via a GFCI breaker at the panel.
The manual can beat the code table. Spa makers (Bullfrog, for example) commonly specify 6 AWG copper minimum for 50–60 A spa circuits — stricter than what the ampacity table alone allows for THHN. When the manufacturer's wire spec is larger than the code minimum, the manual governs.
🔦 The maintenance disconnect
Article 680.13 requires a disconnecting means for the spa that is within sight of it, readily accessible, and at least 5 feet horizontally from the water (unless separated by a permanent barrier). This lets a service tech kill power at the tub without walking back to the panel — and keeps the disconnect far enough away that nobody reaches it from inside the water.
It's the piece most DIY spa installs miss. A breaker in the basement panel is not a substitute for the local disconnect at the tub.
🔗 Equipotential bonding
This is the rule unique to pools and spas, and the one that saves lives. Equipotential bonding (680.26) ties all the metal in and around the spa — the pump, the metal frame, any metal within 5 feet, and the reinforcing steel if it's in a deck — together with a solid #8 AWG copper wire. The goal isn't to carry fault current to ground; it's to keep everything a swimmer can touch at the same voltage, so there's no potential difference to shock across.
Bonding is separate from the equipment ground in the circuit, and it must be a continuous solid conductor. Skipping it is both a code failure and a genuine hazard.
⛏️ Burial depth for the run
If the circuit runs underground to an outdoor spa, the burial depth depends on the wiring method (Table 300.5):
- UF cable, direct burial — 24 inches
- PVC conduit (rigid nonmetallic) — 18 inches
- Rigid or intermediate metal conduit — 6 inches
Deeper conduit costs more trenching but protects the run; the shallow metal-conduit option trades material cost for less digging.
✅ The bottom line
A spa circuit is a dedicated 50–60 A, GFCI-protected, four-wire circuit, sized to the nameplate (and to the manual's wire spec, which often means 6 AWG copper). Add the three Article 680 requirements every time: GFCI on all outlets, a maintenance disconnect 5+ feet from the water and within sight, and #8 solid copper equipotential bonding. Bury the run to the Table 300.5 depth for your method.
Spa wiring is life-safety wiring around water — this is a planning tool, not a substitute for a licensed electrician and permit. Size the circuit with the hot tub wiring calculator, then have the install inspected. Adopted NEC editions and local amendments vary.
Estimate your Hot Tub Wiring materials
What size wire and breaker for a hot tub? Free NEC Article 680 calculator — GFCI circuit, wire gauge, the 5-ft disconnect rule, bonding, and burial depth.
Estimate with the Hot Tub Wiring Calculator →