Equipotential Bonding and the NEC/2008

Equipotential Bonding
and the NEC/2008
In the National Electrical Code (NEC), the purpose of
the section on pool bonding has remained consistent:
to reduce or eliminate voltage gradients in pool areas.
That said, the change in language in the NEC/2005
caused some confusion regarding Section 680.26,
"Equipotential Bonding," when the word “Equipotential”
was added to the title (which had been "Bonding") and
requirements were added to the code. An article in the
Summer/Fall 2007 Construction Code Communicator
attempted to clarify the equipotential bonding
requirements of NEC/2005. This article attempts to
clarify the equipotential bonding requirements of the
NEC/2008. This appears to be particularly confusing
because of the way that the sections were subdivided.
1. Pool Shells, NEC/2008 Article 680.26(B)(1) –
Conductive pool shells consist of poured concrete,
pneumatically applied or sprayed concrete, or concrete
block with painted or plastered coating materials. Nonconductive
pool shells include vinyl liners and
fiberglass composite materials.
(a) – Typically, structural reinforcing steel is
used in the conductive pool shells listed above. To be
considered bonded, unencapsulated structural
reinforcing steel is permitted to be secured together by
steel tie wires.
(b) – When the pool reinforcing steel is
encapsulated in a nonconductive material (coated
rebar), then the bonding requirements, which are
summarized in 1a above, no longer apply; however, a
copper conductor grid must be installed within or under
the pool and no more than 6 inches from the outer
contour of the pool shell. The grid must be constructed
of at least a #8 AWG bare solid copper conductor
bonded to each other at all crossing points, and
arranged in a 12 inch by 12 inch (12" X 12") grid with a
tolerance of 4 inches.
2. Perimeter Surfaces, NEC/2008 Article
680.26(B)(2) – The NEC/2008 requires that ANY
surface (e.g. soil, grass, concrete, pavers, etc.) around
the pool or outdoor spa/hot tub must have
equipotential bonding.
(a) – Unencapsulated structural reinforcing
steel (summarized in 1a above) installed in a perimeter
surface that extends three (3) feet from the pool wall is
required to be bonded back to the pool shell at four (4)
uniformly spaced points around the pool.
(b) – When the perimeter surfaces contain reinforcing steel encapsulated in a nonconductive
material (coated rebar), or when the pool is
fiberglass, or vinyl, then a copper conductor that
meets the following must be used: (1) a minimum of
a #8 AWG bare solid copper bonding conductor that
follows the contour of the perimeter surface between
18 and 24 inches from the inside walls of the pool;
(2) the bonding conductor shall be secured within
(i.e. paved surface) or under the perimeter surface 4
to 6 inches below the subgrade (soil); and (3) listed
splicing devices must be used.
3. Pool Water, Article 680.26(C)– This section
requires a minimum conductive surface area of 9
square inches to be installed in contact with the pool
or outdoor spa/hot tub. For example, the metal
handrails of a ladder may be used as long as a
minimum of 9 square inches is submerged in the
pool in contact with the water. If there is no ladder
(or other conductive surface), a component that
meets the requirements of this section may be used.
Please keep in mind that there are other items that are
part of the equipotential bonding system that are not
discussed in this article. As per Section 680.26(B), the
following are also included, as applicable: metallic
components, underwater lighting, metal fittings,
electrical equipment, and metal wiring methods and
equipment.
An example of typical equipotential bonding setup for
an unencapsulated reinforced steel inground pool is
provided below as a convenient accompaniment to this
article. Please note that the graphic is an illustration
only and is not a substitute for the code text.
If you have any questions, please call the Code
Assistance Unit at (609) 984-7609.
Source: Rob Austin and Suzanne Borek
Code Assistance Unit