Hydromassage tub bonding

Some jurisdictions require the 8 AWG copper bonding conductor used to bond the pump and other metallic piping of a hydromassage bathtub to be run back to the service or panelboard where the pump branch circuit originates or the 8 AWG bonding conductor from the hydromassage bathtub equipment be connected to the closest grounding electrode. Is this required by the National Electrical Code?

The bonding conductor does not need to be “run back” to anywhere. A new last sentence in the 2008 NEC clarifies the bonding requirements for hydromassage bathtub. Bonding applies to all metal piping systems and all grounded metal parts in contact with the circulating water of the hydromassage tub. Section 680.74 states, “The 8 AWG or larger solid copper bonding jumper shall be required for equipotential bonding in the area of the hydromassage bathtub and shall not be required to be extended or attached to any remote panelboard, service equipment, or any electrode.”
A design shows two emergency generators installed in parallel and connected to a single 1,200-ampere, 277/480-volt outdoor switchboard at a hospital. The switchboard is a three-section with an overcurrent protective device in the first section supplying a critical branch transfer switch; an overcurrent protective device in the second section supplying the hospital life safety branch transfer switch; and three overcurrent protective devices in the third section supplying a hospital equipment system transfer switch, a transfer switch for legally required standby loads and a transfer switch for optional standby loads. There is a load pickup and shedding system for the switchboard. Is this a Code-compliant design based on the switchboard separation requirements?

Section 517.26 for essential electrical systems for healthcare facilities requires compliance with Article 700 for emergency systems, unless amended by the requirements in Article 517. The requirements for the separation of emergency (Article 700), legally required standby (Article 701), and optional standby overcurrent protective outdoor spa devices and conductors (Article 702) have been clarified in the 2008 NEC by adding new 700.9(B)(5) permitting wiring from an emergency source of power to supply any combination of emergency, legally required, and optional loads as long as the requirements in 700.9(B)(5) are followed.

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The important text of this requirement is that wiring from an emergency source or emergency source distribution overcurrent protection to emergency loads shall be kept entirely independent of all other wiring and equipment, unless otherwise permitted in 700.9(B)(1) through (5). New (5) covers wiring from an emergency source to supply any combination of emergency, legally required, or optional loads in accordance with (a), (b) and (c) to be as follows:

“(a) From separate vertical switchboard sections, with or without a common bus, or from individual disconnects mounted in separate enclosures;

“(b) The common bus or separate sections of the switchboard or the individual enclosures shall be permitted to be supplied by single or multiple feeders without overcurrent protection at the source

“Exception to (5)(b): Overcurrent protection shall be permitted at the source or for the equipment, provided the overcurrent protection is selectively coordinated with the down-stream overcurrent protection.

“(c) Legally required and optional standby circuits must not originate from the same vertical switchboard section, panelboard enclosure, or individual disconnect enclosure as emergency circuits.”