Blade terminal tap fuse

An electrically tappable miniature fuse which includes a housing from which the first ends of a pair of parallel blade terminals extend for engaging the contact elements in a fuse box or panel and where in at least one of the blade terminals includes a second end which is freely accessible either within, or which extends from, the housing remote from the first end thereof so as to permit an electrical connector to be selectively engagable therewith.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention is generally directed to miniature fuses of the type which 
are normally associated with automotive vehicles and more specifically to 
blade type terminal fuses which are adapted to provide a tappable 
electrical connection for use in installing auxiliary electrical equipment 
within a vehicle or other equipment without requiring the electrical 
wiring or electrical harnesses associated with the electrical system of 
the vehicle or equipment to be disturbed or spliced. The tap fuses of the 
present invention permit auxiliary electrical equipment to be connected to 
a vehicle or other electrical system by directly tapping a source of 
electrical power through the fuse elements conventionally associated with 
such systems. In one embodiment of the invention, one of the blade 
terminals of each fuse extends outwardly or is spaced from the fuse 
housing so as to be accessible to a female electrical connector mounted at 
the remote or free end of an electrical wire or cable associated with the 
auxiliary equipment being installed. 
In one form of the invention, the auxiliary blade terminal extends from the 
insulated housing which normally surrounds the terminals of the fuse so 
that the electrical connection is made exteriorly with respect to the 
housing. In this embodiment, the auxiliary terminal may be selectively 
covered by a protective insulated cap when not in use. 
In another form of the present invention, the auxiliary blade terminal may 
be mounted within in a recess within the housing which recess is of a size 
to permit a female electrical connector to be inserted therein to 
electrical contact the auxiliary blade terminal. 
In another embodiment of the present invention, both of the blade terminal 
elements of the fuse will include remote auxiliary end portions which may 
be tapped by a pair of electrical connectors mounted to the remote or free 
ends of a pair of wires or electrical conductors which extend to a remote 
fuse condition indicator panel. In this manner, the condition of the fuse 
element may be displayed to a remote location such as the dashboard of the 
vehicle so that the vehicle operator will have an immediate indication as 
to a blown fuse. In this embodiment, the auxiliary blade terminal elements 
may either be recessed within the housing or extend from the housing as in 
the case with the first embodiment of the invention. 
2. Description of the Related Art 
Until recently, the automotive and other industries have relied entirely on 
conventional cylindrical glass fuses to protect against electrical 
overloads and overheating in low amperage electrical wiring. Such fuses 
are generally placed in electrical circuits so as to prevent an overload 
due to faulty wiring or equipment conditions with the amperage ratings of 
the fuse elements generally not exceeding 25 amps. In vehicles, such 
electrical systems may control the operation of headlights, tail lights, 
running lights, dashboard lights, instrumentation, horns, wiper systems, 
electrical doors, windows and locks, radios and other associated 
equipment. As many vehicle operators have experienced over the years, the 
simple matter of a blown fuse in an electrical circuit can be a very 
complicated and time consuming replacement project. 
Often times the fuse panels or boxes for automotive and other equipment are 
placed in inconvenient locations, either beneath the dashboards or within 
closed compartments. Due to the complexity and the problems associated 
with replacing conventional glass type cylindrical fuses, the automotive 
and other industries have begun utilizing what are known as miniature 
blade fuses. Blade fuses are more compact and easily handled during 
replacement and removal and provide not only an economy of space but are 
easier to manipulate when being placed into an electrical panel or box. 
Miniature blade fuses are generally constructed of a conductive metallic 
material which is embedded into an insulated housing which is easily 
gripped for manipulation. The fuses include parallel and coplanar terminal 
blades that extend outwardly so as to be engagable within the sockets 
provided within fuse boxes or panels. The terminals are connected by a 
thin strip of conductive material which extends between the terminals 
within the housing. The housings are generally designed so that when the 
thin fuse strip overheats and melts or breaks an indication of the failed 
condition of the fuse is easily discernable through the housing. Examples 
of such prior art blade type fuses are disclosed in U.S. Pat. Nos. 
3,909,767 to Williamson et al and 4,999,447 to Greenberg. 
Unfortunately, although there has been significant improvement in the 
economy and the handling of fuse elements utilized in flat blade type 
fuses, there remain problems which are encountered on a regular basis with 
respect to the installation of new electrical equipment into a vehicle's 
or other equipment's electrical system. In many instances, it may be 
desired to install auxiliary electrical equipment such as radios, cassette 
players, television sets and telephones into cars, trucks, vans and the 
like. When this equipment is installed in a vehicle, it must be connected 
to the vehicle electrical system. In order to accomplish this, prior art 
techniques have required that the electrical line from the equipment be 
tapped to one of the electrical wires leading to or from the fuse box or 
fuse panel. This type of connection not only is unsafe but requires a 
great deal of experience in knowing which lines of the electrical system 
can be appropriately spliced to provide power to the auxiliary electrical 
equipment. This process is both time consuming and costly and often 
requires the need of experienced personnel. However, even with experienced 
personnel, electrical harnesses are often overly complex and require that 
electrical diagrams of the electrical system be available. This requires 
that installers have access to the electrical diagrams of many types of 
automotive vehicles or other electrical systems. 
Even with sufficient knowledge to install such auxiliary equipment, a great 
deal of work is often involved when it becomes necessary to disassemble a 
wiring harness and obtain a splice connection with an appropriate 
electrical line. To forego this problem, some installers make an 
electrical connection directly with one of the fuse elements or fuse 
contacts in a fuse box. This is generally accomplished by taking a small 
gauged electrical wire and wrapping it around the blade contact of a 
conventional blade type fuse and then inserting the fuse back into to its 
electrical socket. Such splices are not only unsafe but are not reliable. 
Due to the small dimensions between the terminal blades of conventional 
blade fuses, any attempt to wrap or otherwise attach a supplemental 
electrical wire to one of the blade terminals can result in an arcing 
between the terminals creating a safety problem or resulting in the 
destruction of the fuse element. Further, many auxiliary electrical lines 
include larger gauge electrical wire and are not therefore easily wrapped, 
soldered or secured to the terminal blades. In these instances, a 
secondary splice must be made between the large wire and a smaller wire 
and thereafter the mechanical splice being made to the blade terminal of 
the flat blade fuse. 
Even without regard to the obvious safety problems involved with making 
mechanical splices to existing blade type fuses, due to the remote 
location of the fuse elements themselves, installation can be extremely 
difficult. Even where the splice is made while the fuse is out of a fuse 
box, attempting to re-align the fuse blades to their proper contacts 
within the box with the auxiliary electrical wire attached thereto can be 
a challenging task. 
In view of the foregoing, it is necessary to provide a convenient, easy, 
safe and reliable method for providing a connection to a source of 
electrical energy for auxiliary electrical equipment especially in 
automotive vehicles. Further, by providing a source of tappable electrical 
energy through a fuse element, it is possible to install the equipment in 
a safe manner insuring that the electrical line will be protected from 
overload and overheat conditions. 
SUMMARY OF THE INVENTION 
This invention is directed to a miniature blade type fuse having a pair of 
parallel and generally coplanar terminal elements which are mounted within 
an insulated housing and which are interconnected by a thin fuse element 
or metallic strip within the housing. Each of the blade elements includes 
a first end which extends outwardly from the housing so as to provide for 
normal electrical contact with the socket of a fuse box or panel. In one 
embodiment of the invention, at least one of the blade elements includes 
an auxiliary end which is spaced from the surrounding insulated housing so 
as to provide a tappable source of electrical energy. Such auxiliary or 
second end of one of the blade elements is designed to permit an 
electrical connector to be attached thereto so that electrical energy 
passing through the fuse element may be utilized to power auxiliary 
electrical equipment. In a first form of one embodiment of the invention, 
the auxiliary end of the blade terminal extends outwardly from the housing 
so as to be easily accessible for a female electrical connector to be 
secured thereto. When not in use, an insulated cover may be placed over 
the blade terminal to insure that no arcing or accidental grounding is 
possible. In a second form of the first embodiment of the invention, the 
auxiliary terminal end is recessed within the fuse housing with a space 
being provided around the auxiliary terminal so that a female electrical 
connector may be inserted within the space in surrounding relationship 
with the auxiliary terminal. Again, to prevent any accidental arcing, 
contact, or grounding of the terminal element, a plug may be inserted 
within the recess created in the housing when the auxiliary terminal is 
not in use. 
In a second embodiment of the present invention, each of the blade terminal 
elements associated with the fuse include an auxiliary blade end which may 
be formed either extending from the housing or inset within the housing. 
In this embodiment, an electrical circuit may be created through the fuse 
so that a remote indication of the condition of the fuse may be readiliy 
displayed to the operator of a motor vehicle or other type of equipment. 
With this system, a remote display box would have a first lead extending 
to one of the blade terminal elements and a second lead extending from a 
visual light source or other indicator in the display box to the other 
blade terminal element. In the event that a fuse fails, the indicator 
would reflect the inoperable condition of the fuse element. Again, when 
not in use, a protective cap would be provided over the auxiliary ends or 
plugged into the recesses created in the housing for the auxiliary 
terminals. 
In either embodiment of the present invention, the contacts which are made 
with the auxiliary terminals should be insulated to insure that no arcing 
or direct contact can be made with such elements. 
It is a primary object of the present invention to provide a tap adapter 
for low current electrical systems which includes a flat blade type 
miniature fuse wherein one or more of the fuse blades includes an 
auxiliary terminal which may be tapped by an auxiliary or outside 
electrical line so as to provide a source of electrical energy to a remote 
electrical component. 
It is another object of the present invention to provide a flat blade type 
fuse element with auxiliary electrical terminals which permit the fuse to 
be tapped directly without requiring further modification to the fuse box 
or the associated electrical wiring incorporated with the electrical 
system going to and from a fuse box. 
It is also an object of the present invention to provide miniature low 
voltage fuse elements of the type which are conventionally utilized in 
automotive vehicles with auxiliary terminal elements which may be 
selectively utilized and tapped to provide a source of electrical energy 
to a remote electrical component and wherein the electrical contact is 
created without having to disturb the vehicle wiring or the wiring harness 
associated therewith. 
It is another object of the present invention to provide miniature flat 
blade type fuses which may include a pair of auxiliary electrical contacts 
or terminals which may be selectively tapped so as to create an electrical 
circuit which may be utlized to give a remote indication of the continuity 
of the fuses.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
With continued reference to the drawings, FIGS. 1 and 2 show a first 
embodiment of the present invention. In this embodiment, the tap fuse is 
designed to provide a quick connect for an auxiliary electrical line or 
wire W such as shown in dotted line in FIG. 2. The wire may extend to an 
electrical component or unit which is to be connected to the electrical 
system in which the fuse is utilized. As previously discussed, it is the 
primary intent of the present invention to provide a tap for flat blade 
fuses which are conventionally used in the automotive industry. Such fuses 
are rated generally between 5 and 30 amps and are placed within a fuse box 
so as to terminate the electrical circuit from the power source to an 
electrical unit when there is an over-voltage or the wire is overheated. 
When it is desired to install an auxiliary electrical component such as a 
telephone or radio in an automobile, it is necessary to connect such 
components to the vehicle's electrical system. By utilizing the tap 
adapter shown in FIGS. 1 and 2, it is possible to accomplish the 
connection directly through the fuse elements in the vehicle's electrical 
system. In this embodiment, the tap fuse 10 includes an insulated plastic 
body portion 11 having an upper end 12, lower end 13, sidewalls 14 and 
front and rear walls 15. The housing 11 is formed of a suitable electrical 
insulated plastic material which may be molded about the remaining 
conductive components of the fuse. Such plastics not only exhibit 
electrical insulating properties but are fire resistent and may include 
nylon, polystyrenes and the like. Preferably, the housing is transulscent 
or transparent so that the condition of the fuse link embedded therein can 
be determined visually. 
The tap adapter includes a pair of electrically conducting blade elements 
16 and 17 which have first end portions 18 and 19 extending outwardly from 
the lower end 13 of the housing. The end portions 18 and 19 of each of the 
terminal elements 16 and 17 are designed to be engagable within a female 
socket of a fuse box or panel (not shown). 
Each of the blade elements 16 and 17 includes an opening generally 
indicated at 20 through which the plastic material forming the housing may 
h=molded when the fuses is formed. The blade element 16 is shown as 
extending through a channel 21 having openings along the upper and lower 
surfaces of the the housing. The blade element 16 therefore includes an 
upper extending auxiliary end portion 22 which is designed to provide an 
electrical tap for the electrical wire W. Blade element 17 is shown as 
being shorter and not extending through the housing 11 but being embedded 
within a closed channel 23 which is open only along the lower end 13 of 
the housing. The two blade elements 16 and 17 are separated by a pair of 
electrically insulating walls 24 which are provided to prevent any arcing 
of current between the blade elements. An electrical contact is 
established between the blade elements 16 and 17 by a metallic or other 
electrically conductive fuse element 25 which extends through openings 26 
molded in each of the walls 24. In practice, it is generally preferred 
that the blade elements 16 and 17 be integrally formed with the small 
connecting fuse element 25. Such materials may be stamped from a sheet of 
metallic or other conductive material with the connecting element being of 
a size to determine the proper amperage rating for the fuse. In use, when 
the connecting element 25 fails due to electrical conditions in a circuit, 
the transparent housing will permit a visual inspection to verify the fuse 
should be replaced. 
When the tap fuse 10 of the present invention is not in use, a separate 
electrically insulated cover or cap 27 is provided which fits over and 
closely engages the auxiliary portion 22 of the blade element 16. The 
cover or cap includes a main body portion having an opening therein which 
is of a size to cooperatively receive the upper end or auxiliary end 22 of 
blade element 16. The body portion also engages the upper end 12 of the 
tap fuse when placed over the auxiliary blade element 22. The cover 
further includes outwardly extending flanges 28 which may be engaged by a 
screwdriver or by finger nail so as to lift the cover from the auxiliary 
blade element 22. 
With the cover removed, the tap adapter of the present invention is ready 
to be utilized to provide a source of electrical power to an auxiliary 
electrical component which is to be connected to the electrical system in 
which the fuse is installed. As shown in FIG. 2, a crimpable connector 
element 30 is attached to the free end of the electrical wire W. The 
crimpable connector includes an outermost insulated housing 31 which 
extends upwardly over the splice with the electrical wire as shown at 32. 
By placing the crimpable connector over the auxiliary end 22 of blade 
element 16, an electrical contact is immediately established through the 
electrical wire 20 to a remote electrical component (not shown). 
With specific reference to FIGS. 3 and 4, a second embodiment of the 
invention is disclosed in greater detail. In this embodiment, the tap fuse 
10' includes a housing 11 which is substantially identical to the housing 
shown and discussed above with respect to the embodiment of FIGS. 1 and 2. 
The only difference between the two housings is that the channel 21 in 
which the blade contact element 16' is located includes a bore 36 along 
the upper portion of the channel adjacent to the upper end 12. The bore 36 
is of a size to permit a female electrical connector 30' to be inserted 
therein in order to contact the blade element 16'. 
The blade contact element 16' of the present embodiment is also modified 
and includes an upper or auxiliary contact element 35 which is spaced 
inwardly of the housing so as be positioned totally within the bore 36. In 
this manner, the auxiliary contact element 35 is positioned entirely 
within the electrically insulated housing. When electrical contact is 
desired, the electrical connector is inserted within the bore in the 
housing as opposed to being inserted over the contact element outside of 
the housing as was the case with the prior embodiment. 
When the electrical contact element 35 is not in use, an electrically 
insulated cover or cap member 38 is provided which includes a rectilinear 
sleeve 99 of a size to fit over the electrical contact element 35 and is 
cooperatively seated within the bore 36. The cover 38 includes outwardly 
extending flange portions 40 which provide a gripping surface for removing 
the cover from its covering engagement with the contact element 35. In the 
present embodiment, the female electrical connector 30' is somewhat 
smaller than the connector 30 disclosed with respect to the embodiment of 
FIGS. 1 and 2. In order to prevent any electrical arcing or short in the 
system, the connector is provided with an electrically insulated sleeve 
which completely surrounds the electrical contact elements. 
With specific reference to FIG. 5, a third embodiment of the present 
invention is shown in greater detail. In this embodiment, the tap fuse 10" 
is shown as including a housing 11" which is substantially identical to 
the housing discussed above with respect to FIGS. 1 and 2 with the 
exception that the channel 23 shown in FIG. 2 is made completely through 
the housing so as to be open through the upper end 12 and lower end 13. In 
the present embodiment, both of the fuse blade contact elements 16 and 17" 
include auxiliary upper end portions 22 and 42 respectively. The auxiliary 
end portions are integrally formed with the blade element and provide 
electrical contacts through each of the blade elements of the fuse. In 
this manner, an electrical circuit can be created through blade elements 
16 and 17' to a remote indicator source by connecting electrical wires 
(not shown) from the auxiliary element 22 to a remote panel where an 
indicator light is connected in series with a second wire (not shown) 
which is connected to the auxiliary blade element 42. In this embodiment, 
when the fuse link 25 which is located within the housing fails due to a 
condition in the circuit, the indicator light connected through the blade 
elements of 16 and 17' will give a visual indication of the failure. As 
with the prior embodiments, when blade contacts 22 and 42 are not in use, 
they are covered with a protective and electrically insulated cover or cap 
similar to that shown in FIG. 1. As an alternative, a single protective 
cover may be provided to extend over both of the blade elements 22 and 42. 
As a further alternative, the blade elements 22 and 42 may be formed 
similarly to the auxiliary blade element 35 shown in FIG. 3. In this 
embodiment, the blade elements 22 and 42 would be located within the 
housing and the electrical connection would be made in a manner similar to 
the connection discussed with respect to the embodiment of FIGS. 3 and 4. 
The tap fuses of the present invention are utilized in place of the 
conventional blade type fuses conventionally utilized with automobile and 
other electrical circuits and which usually have amperage ratings not 
exceeding 25 to 30 amps. The tap fuses are installed in the same manner as 
conventional blade type fuses. However, when it is necessary to connect an 
auxiliary electrical unit or component to an electrical system, the 
connection may be made directly through the tap fuse without requiring 
modification to the fuse or without requiring unsafe electrical 
connections to be made by splicing wires or wrapping a blade of a 
conventional fuse with a conductor. The tap fuses therefore make it 
possible to safely and quickly install auxiliary electrical equipment to 
an electrical circuit without disrupting the electrical harnessing or 
wiring and provide a safe contact between the various electrical 
components. For safety, it should be assumed that any auxiliary or add-on 
electrical equipment employ the use of an in-line or built in fuse for its 
own protection as well as protection of the electrical system.