Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2001-11-20
2004-04-27
Rosenbaum, Irene Cuda (Department: 2726)
Metal working
Method of mechanical manufacture
Electrical device making
C439S800000
Reexamination Certificate
active
06725524
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to electric motors, and more particularly to a bonding lug apparatus for devices such as electric motors installed within a distance of a swimming pool, hot tub, spa, or the like.
Permanent installation of pools and equipment associated with the pools (e.g., pumps, filters, ladders, decking, fencing, lighting, and the like) generally requires compliance with a number of installation standards. The installation standards may include standards such as those provided by National Electric Code (“NEC”) (e.g., NEC Article 680/22), Underwriters Laboratories, Inc. (“UL”) (e.g., UL Standard 467) and local authorities (e.g., municipal statutes that are often based on the national standards provided by NEC and UL). Standards relating to bonding often require that devices or conductive materials (e.g., metal) located within a distance of the pool (i.e., in the pool area) be bonded together to form a bonding grid of the pool area.
The purpose of forming a bonding grid is to eliminate the potential for an electrical energy differential in the pool area (i.e., shock hazard). The bonding grid acts as a path of less resistance than does the path of resistance provided by a human and/or an animal (e.g., cat or dog) located in the pool area. Any stray electrical energy inside the pool area is therefore conducted through the bonding grid instead of through the human and/or the animal located in the pool area.
The size of the bonding grid often depends on the amount of conductive material located in the pool area. The devices or conductive material in the pool area may include metal parts of the pool structure, metal ladders, metal railings, metal fittings utilized to secure the metal ladders and the metal railings to the pool, metal parts of decking surrounding the pool, metal fencing surrounding the pool, metal parts of electrical equipment, metal forming shells utilized to enclose light fixtures, and the like. A small bonding grid may include only a single bonding conductor that bonds together a limited number of conductive materials located in the pool area. Alternatively, a large bonding grid may include a high number and/or a high volume of conductive materials such as the metal parts of the pool structure bonded to the metal parts of the decking bonded to a bonding conductor that bonds the remaining conductive materials in the pool area to the larger segments of the bonding grid.
Regardless of the size of the bonding grid, the individual installing the pool and the associated equipment must make sure to comply with all applicable standards. These standards typically require bonding of devices such as electric motors located in the pool area (e.g., a pool pump motor) to the bonding grid of the pool area.
Bonding lug apparatus for bonding an electric motor to a bonding grid are generally known. Typically the bonding lug apparatus bonds the electric motor to a bonding conductor which is part of the bonding grid. The bonding conductor includes a solid eight (or larger) gauge bare copper wire. The conductor generally does not require use of insulation or a conduit because the conductor does not carry electrical energy under normal operating conditions (i.e., only utilized when an electrical energy differential is present in the pool area). Existing bonding lug apparatus, such as a bonding lug apparatus
10
illustrated in
FIGS. 1A-B
and
2
A-C, require that a bonding conductor
14
be passed through an aperture
18
in a bonding lug
20
and then bonded to the bonding lug
20
by tightening a threaded fastener or screw
22
down upon the conductor
14
such that the conductor
14
is captured between the bonding lug
20
and the bottom
26
of the screw
22
. The screw
22
is threaded into an aperture or opening
28
in the lug
20
.
As is illustrated in
FIGS. 2A-C
, the bonding lug
20
may be connected to an electric motor
34
on the housing
38
of the motor
34
using a threaded fastener or screw
42
. When properly installed, the conductor
14
is electrically coupled to the bonding lug
20
and the bonding lug
20
is electrically coupled to the housing
38
. Generally an adequate electrical coupling is formed between the conductor
14
and the bonding lug
20
. The electrical coupling may be formed via direct contact between the conductor
14
and the bonding lug
20
and/or via indirect contact through the screw
22
. The screw
22
is formed of an electrically conductive material and when the screw
22
is tightened down on the conductor
14
an electrical coupling is formed between the conductor
14
and the screw
22
. The screw
22
is electrically coupled to the bonding lug
20
through the interaction between the threads of the screw
22
and the corresponding threads in the aperture
28
of the bonding lug
20
.
The contact between the bottom of the bonding lug
20
and the housing
38
may provide some degree of electrical coupling, however, the contacting surfaces of the bonding lug
20
and/or the housing
38
may include paint and/or other contamination that can diminish such electrical coupling. The paint and/or other contamination may additionally affect the degree of electrical coupling between the screw
42
and the bonding lug
20
as well as the direct contact between the conductor
14
and the bonding lug
20
discussed above.
The screw
42
is utilized to electrically couple the bonding lug
20
to the housing
38
. Typically, the bonding lug
20
includes an aperture (not shown) through which the screw
42
passes and which is only a clearance aperture. Therefore, passing the screw
42
through the clearance aperture does not provide a reliable electrical coupling between the bonding lug
20
and the screw
42
(i.e., the threads of the screw
42
are not electrically coupled to the bonding lug
20
in a fashion similar to the way the threads of the screw
22
are electrically coupled to the corresponding threads of the aperture
40
). If the screw
42
is not electrically coupled to the bonding lug
20
then the bonding lug
20
is likely not electrically coupled to the housing
38
.
Accordingly, existing bonding lug apparatus (such as the bonding lug apparatus
10
) utilize at least one star washer (not shown) (e.g., a star washer located around the screw
42
between the head
50
of the screw
42
and the bonding lug
20
and/or a star washer located around the screw
42
between the bonding lug
20
and the housing
38
). Alternatively, or in addition, the screw
42
can have a serrated head to provide an electrical coupling between the screw
42
and the bonding lug
20
and therefore between the bonding lug
20
and the housing
38
. The threads of the screw
42
generally become electrically coupled to the housing
38
when threaded into the housing
38
, therefore, the coupling that generally presents a problem is the coupling between the screw
42
and the bonding lug
20
. The star washer located between the head
50
and the bonding lug
20
and the serrated head are both designed to increase the reliability of the electrical coupling between the bonding lug
20
and the screw
42
. The star washer located between the bonding lug
20
and the housing
38
is designed to increase the reliability of the electrical coupling between the bonding lug
20
and the housing
38
. Use of the above techniques typically results in a proper installation.
While installing a motor
34
in a pool area (not shown) the efficiency of the installer is important. Currently, the amount of time it takes the installer to bond the motor
34
to the bonding grid (not shown) includes passing the conductor
14
through the aperture
18
and utilizing the above techniques to ensure all corresponding parts are electrically coupled as required. The installer may pass the entire length of the conductor
14
through the aperture
18
or the installer may cut the conductor
14
, pass a portion of the conductor
14
through the aperture
18
and then reconnect the cut portions of the conductor
14
together to form a continuous
Lin Chih M.
Watkins William J.
A. O. Smith Corporation
Cuda Rosenbaum Irene
Kenny Stephen
Michael & Best & Friedrich LLP
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