My invention relates to insulators for supporting electrical transmission lines and pertains to that class of such insulators which from the nature of the service they perform are termed dry spot insulators.

The principal objects of my invention are to provide a dry spot insulator of rugged and simplified construction and one in which the insulated portion of the conductor forming the dry spot section of the line is maintained free from moisture under all possible weather conditions.

It is well known that with the ordinary insulator to which a line wire is attached or terminated, when an insulated tap or extension is taken therefrom for cross connection or for leading into a test box, terminal station or office, a certain amount of surface leakage takes place not only to the ground but to adjacent conductors especially in damp weather due to absorption of moisture by the insulated coating of the leading in or tap wire.  Several types of insulators in which a portion of the insulated tap or branch wire is maintained in a manner which provides a housing for a portion of the insulated wire to effect a dry spot in the conductor, have been devised.  These have usually been of the two piece type in which the insulated conductor is maintained between the two parts of the insulator and while they provide protection against direct precipitation of moisture on the conductor they do not prevent moisture from traveling through the insulation by capillary attraction and thus fail in their purpose.  Further they are unduly costly to manufacture and difficult to install and maintain.

I overcome all of these objections and attain other desirable features which will hereinafter be pointed out and discussed by employing a one piece insulator provided with an annular recess in which a section of the insulated conductor is embedded in an insulating and binding medium impervious to moisture and which thus seals the section of the conductor in such manner that capillary attraction can not distribute moisture throughout the insulation thereof.

In the drawings which accompany and form a part of this specification and in which like reference numerals designate corresponding parts throughout:

Fig. 1 is a partially sectioned full sized elevation of my complete device.

Fig. 2 is a section of the same taken on the line H--H of Fig. 1.

Referring now to the figures my device comprises an insulating member 10 preferably formed of glass in the shape of a conical frustum and provided with all encircling annular groove 15 adapted to support a line

conductor.  A central recess is provided with the usual internal square thread that the device may be attached to a pole pin.

An outer petticoat 16 and an inner petticoat 12 are provided, forming an annular recess there between which is re-entrant from the base of the insulator and in which a section of the insulated conductor 14 is maintained as shown in the figure by a wax or cement 13.  This wax or cement is preferably known as Leverite and has a pouring point of approximately degrees F. and remains hard and solid at all normal atmospheric temperatures.  Leverite is the trade name for a natural asphalt having a high melting point.

It will be observed from the foregoing that my device is rugged, simple and presents no manufacturing difficulties, and that further it may be installed as a unit, as an ordinary insulator and requires a minimum maintenance. As the binding material 13 is impervious to moisture and is poured in around the conductor 14 in a hot molten state, it is obvious that the union of the material 13 with the insulated coating of the wire 14 will be so intimate that moisture will be unable even by capillary attraction to traverse that portion of the insulation embedded in the material 13 and that therefore under all possible weather conditions my improved device will present an actual dry spot or section in the insulated conductor 14.

Having thus completely described my device, I claim--

1. An insulator comprising, a unitary body formed of vitreous material to have substantially a conical shape, the entire outer surface of said body being imperforate and unbroken and adapted to shed moisture from all portions thereof, a centrally disposed aperture re-entrant from the base of said body, an annular recess re-entrant from the base of said body, a section of insulated conductor a portion of which is carried in said annular recess and partially encircles said centrally disposed aperture and a material impervious to moisture covering and maintaining in said recess that portion of conductor carried therein.

2. A dry spot insulator comprising a unitary body provided with an imperforate, unbroken, substantially conical surface of revolution, a centrally disposed aperture re-entrant from the base of said body, an annular recess surrounding said centrally disposed aperture and likewise re-entrant from the base of said body, an insulated conductor a portion of which is maintained in said recess and a plastic material impervious to moisture and substantially solid at normal temperatures in said recess and binding a portion of said insulated conductor therein.

    RUFUS GOULD.