Waterproof enclosure for electrical devices

Details Waterproof enclosure for electrical devices Waterproof enclosure for electrical devices

1999-12-22

2002-04-02

Reichard, Dean A. (Department: 2831)

Electricity: conductors and insulators

With fluids or vacuum

Boxes and housings

C174S050000, C174S017070

Reexamination Certificate

active

06365826

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates generally to enclosures for electrical components and, more particularly, to a waterproof enclosure for electrical devices.
Enclosures are used in electrical power distribution systems to house various electrical components. These enclosures protect the electrical distribution equipment mounted therein from damage. Such applications include electrical switchboards, switchgear, and motor control centers. The degree of protection provided by the enclosure is dictated by the area in which the enclosure is to be located. The National Electrical Manufacturer's Association (NEMA) defines different types of enclosures by the location of the enclosure and the various elements that the enclosure must be able to withstand. For example, NEMA Type 3 enclosures are for outdoor use, and NEMA Type 3R must provide a degree of protection agains falling rain, sleet, and external ice formation. Enclosures may also be designed to meet waterproof ratings as listed in Underwriters Laboratories standard 891 section 35 and ANSI/IEEE standard C37.20.3-1987 Section 5.2.9.
A typical outdoor enclosure (e.g., NEMA Type 3R) is shown in
FIGS. 1 and 2
. The switchboard type enclosure
10
includes a front frame
12
and a roof assembly
14
attached to a switchboard section
16
. Switchboard section
16
is an indoor type enclosure (e.g., NEMA Type 1 and 2), which includes a metal cover secured to a frame
18
and forming side covers
20
and back cover
22
. Mounted within switchboard section
16
are a plurality of electrical devices such as circuit breakers, fusible switches, motor controllers, or other electrical components (not shown). Front frame
12
is attached to the perimeter of the perimeter of the switchboard section
16
. Front frame
12
includes walls
24
extending forward from side covers
20
, and a door
26
. Walls
24
and door
26
protect the electrical components within switchboard section
16
from the elements, while door
26
allows personnel to access these electrical devices. A handle
28
with provisions for a padlock prevent unauthorized access to the electrical devices. Roof assembly
14
includes a sloped hood
30
that extends across the width of switchboard section
16
from side
20
to side
20
. Hood
30
extends a distance (shown here as five inches) past the back cover
22
of switchboard section
16
and past the front of door
26
. Front and rear edges of hood
30
include flanges
32
,
34
that extend downwardly. Secured between flange
32
and front frame
12
and between flange
34
and rear frame
16
are a pair of screen vents
36
, which both extends across the width of hood
30
. Typically, the screen vents
36
are formed of wire or foam filters to keep out water, debris, and insects. A pair of caps
38
are disposed along the edges of hood
30
adjacent sides
20
,
24
.
An exploded view of roof assembly
14
is shown in FIG.
3
. Referring to
FIGS. 2 and 3
, hood
30
includes mounting flanges
50
which extend along sides of hood
30
. Flanges
50
of hood are secured to lifting brackets
52
. Lifting brackets
52
are secured to the frame
18
of switchboard section
16
and extend along the entire length of hood
30
. Lifting brackets
52
provide a lifting point on enclosure
10
if it is necessary to move enclosure
10
. Once enclosure
10
is in position, caps
38
are secured to flanges
50
. An optional center lifting bracket
54
and center cap
56
are shown for use with switchboard sections
16
having a portion of the frame
18
extending through the center of the switchboard section
16
.
The enclosure
10
shown in
FIGS. 1-3
uses front and rear overhangs, formed by the extension of roof assembly
14
past back cover
22
and front of door
26
, to vent heat from the electrical devices mounted within the enclosure. However, the rear overhang increases the area the customer must allocate to the equipment by adding, for example, five inches of depth between the back cover
22
of the equipment and any any object next to which one would place it.
In applications of the enclosure
10
of
FIGS. 1-3
, if a rear overhang cannot be used, the entire roof assembly must be shifted so that the flange
34
on the rear of hood
30
is flush with the back cover
22
. However, this modification eliminates the convective flow of air through the enclosure
10
. Indeed, in enclosures
10
where such a modification is made, the ampere rating of the enclosure must be reduced. In addition, this modification increases the amount of overhang on the front of the enclosure
10
.
It is therefore desirable to provide an enclosure for electrical components having reduced space requirements through removal of the rear overhang, while providing sufficient ventilation to prevent overheating of the internal electrical components, and while meeting waterproof ratings listed in Underwriters Laboratories standard 891 section 35 and ANSI/IEEE standard C37.20.3-1987 Section 5.2.9.
BRIEF SUMMARY OF THE INVENTION
In an exemplary embodiment of the invention, a roof assembly forms the top of an enclosure for electrical devices. The roof assembly includes a hood formed from a sheet of waterproof material. The hood extends across a portion of the top of the enclosure. A cap extends above a portion of the hood, and a channel extends between the cap and the hood. The channel allows the passage of air into and out of the enclosure.


REFERENCES:
patent: 2774808 (1956-12-01), Bullock
patent: 3900700 (1975-08-01), Gaudet
patent: 6067223 (2000-05-01), Diebel et al.
patent: 6088225 (2000-07-01), Parry et al.
patent: 6128870 (2000-10-01), Kohler
patent: 3820107 (1989-12-01), None
patent: 06204667 (1993-01-01), None

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