What size wire is used to bond a hot tub?

NEC 680.26(B) requires a solid copper conductor not smaller than 8 AWG for equipotential bonding. The size does not change with the circuit rating, so a 60 amp hot tub still uses 8 AWG solid.

What size ground wire does a 60 amp hot tub circuit need?

The equipment grounding conductor run with the feeder is sized from NEC Table 250.122, which gives 10 AWG copper for a 60 amp overcurrent device. That is separate from the 8 AWG solid bonding conductor.

What size bonding conductor does a 60 amp hot tub need?

Q: Does the hot tub bonding wire go back to the panel?

No. NEC 680.26(B) states the equipotential bonding conductor is not required to be extended or attached to any remote panelboard, service equipment or grounding electrode. It ties the local conductive parts together.

Eight AWG solid copper, and that number does not move with the size of the overcurrent device. NEC 2023 Section 680.26(B) requires the parts of a permanently installed pool, spa or hot tub listed in that section to be connected to an equipotential bonding grid using a solid copper conductor not smaller than 8 AWG, or a rigid metal conduit or intermediate metal conduit of brass or other identified corrosion resistant metal. A 30 amp tub and a 60 amp tub get the same 8 AWG solid bond.

Bonding is not grounding

The confusion comes from mixing two different conductors. The equipment grounding conductor runs with the feeder from the panel and clears faults, and it is sized from Table 250.122. For a 60 amp overcurrent device that is 10 AWG copper. The bonding conductor under 680.26 does something else entirely: it ties all the conductive parts around the tub to each other so that a person standing in or beside the water cannot be exposed to a voltage gradient between two surfaces. It is an equipotential grid, not a fault path, and 680.26(B) specifically states that it is not required to be extended or attached to any remote panelboard, service equipment or electrode.

What has to be bonded

Section 680.26(B) lists the parts: conductive pool shells, perimeter surfaces within 3 feet of the inside walls, metallic components of the shell structure, underwater lighting metal forming shells, metal fittings that penetrate the structure, electrical equipment associated with the water circulating system including pump motors, metal wiring methods and equipment within 5 feet of the inside wall, and metal parts of the tub structure. Section 680.42(B) then gives outdoor spas and hot tubs a specific allowance: bonding by metal to metal mounting on a common frame or base is acceptable, and small conductive surfaces not likely to become energized, such as air and water jets and drain fittings not connected to metal piping, do not need to be bonded.

The listed self contained unit

Most residential hot tubs are listed self contained units with a factory bonding lug on the equipment pack. The field bond typically consists of an 8 AWG solid copper conductor from that lug to the pump motor bonding lug if the pump is separate, and to any metal within 5 feet. If the tub sits on a poured slab, the perimeter surface bonding of 680.26(B)(2) applies to that concrete, which needs to be planned before the pour rather than after.

Circuit side requirements

Section 680.44 requires GFCI protection for outlets supplying self contained spas and hot tubs, with limited exceptions for listed units marked otherwise. Section 680.42(A)(2) permits liquidtight flexible metal or nonmetallic conduit for the final connection, and 680.12 requires a maintenance disconnecting means readily accessible, within sight, and at least 5 feet from the inside walls of the tub unless separated by a permanent barrier.

Field takeaway

Eight AWG solid copper for the bond regardless of circuit size, 10 AWG copper equipment grounding conductor with a 60 amp feeder, GFCI on the circuit, and a disconnect within sight at 5 feet or more.