Dropout fuse assembly and fuse holder

1. A fuse holder comprising an elongate electrically insulating body providing at least one electrically insulated elongate fuse housing in the form of a passage associated with the body and adapted to receive a fuse wire held under tension therein, a first contact at one end of the body and a second contact at the other end of the body wherein the first contact and second contact are configured for cooperation with cooperant first and second mating contacts of an insulator unit of a dropout fuse assembly such that the body can be installed in such insulator unit as a replacement to an existing dropout fuse element, wherein the first contact is electrically connected to first cooperant mating contact on the fuse holder body and the second contact is electrically connected to second mating contact on the fuse holder body such that a dropout fuse element can be installed on the fuse holder body between said first and second cooperant mating contact on the fuse holder body, wherein electrical conductors are provided in or on the body for defining an electrical circuit between the first and second contact that operatively includes a fuse installed in said passage and a switch adapted to be held open whilst a dropout fuse element is installed between said first and second cooperant mating contact on the body and wherein such switch is adapted to automatically close, in use, when such dropout fuse element that is installed between said first and second cooperant mating contact on the body drops out in consequence of its fuse being blown.

2. The fuse holder of claim 1 in which the first contact on the body includes a generally domed contact surface for snap cooperation with a resilient first cooperant mating contact on an insulator unit having a cooperant recess for receiving the domed contact surface.

3. The fuse holder of claim 1 in which the second contact on the body is an articulated contact assembly including a spring loaded tensioner for holding the fuse wire in tension and a catch for holding it in an extended condition whilst the fuse wire is under tension and for releasing the catch to allow collapse of the articulated contact and allow dropout of the associated fuse element when tension in the fuse wire is released.

4. The fuse holder of claim 1 wherein said first and second cooperant mating contacts on the body of the fuse holder are substantial replicas of the first and second cooperating contacts on a cooperant insulator unit.

5. The fuse holder of claim 1 wherein the electrical conductors defining the circuit that includes said fuse installed in said passage include a first electrical conductor in electrical contact with the first contact and that extends through the body to terminate in a first switch contact on one side of the body and a second electrical conductor extending through the body from a second switch contact on an opposite side of the body to operatively electrically connect with the fuse wire installed in said passage.

6. The fuse holder of claim 1 wherein the switch comprises a generally U-shaped bridging member that is rotatable about an axis extending across the U-shaped bridging member at generally right angles to the arms thereof and that is resiliently angularly biased towards an operative terminal position in which its arms are in electrical contact with a first and a second switch contacts to close a circuit between the first contact and second contact by way of the fuse wire in the passage.

7. The fuse holder of claim 6 wherein at least one retainer is provided for retaining the bridging member in an inoperative terminal position in which it is out of contact with said first and second switch contacts, the retainers being releasable upon or during the dropping out of the dropout fuse element extending operatively between the first and second mating contacts on the body of the fuse holder.

8. The fuse holder of claim 7 wherein the at least one retainer is in the form of a leaf spring one end of which is fixed to the bridging member so as to be rotatable in unison therewith and the other end a region of which cooperates, in use, with a tubular fuse element installed in the fuse holder to hold the bridging member in its inoperative terminal position and wherein the resilient angular biasing of the bridging member urges it into contact with the first and second switch contacts in the absence of said tubular fuse element in the operative position.