GB2198294A

GB2198294A - Terminal device for earthing reinforcing rods

Info

Publication number: GB2198294A
Application number: GB08726901A
Authority: GB
Inventors: Adolf Roth
Original assignee: Georg Fischer AG
Current assignee: Georg Fischer AG
Priority date: 1986-11-29
Filing date: 1987-11-17
Publication date: 1988-06-08
Anticipated expiration: 2007-11-17
Also published as: GB2198294B; DE8632107U1; CH671305A5; AT397743B; SE8704752L; NL8702849A; SE8704752D0; GB8726901D0; ATA300587A; SE464999B

Abstract

An electrical terminal device, for shunting earth currents of electrical installations in a building having metal reinforcing rods (3a, 3b) in the foundation thereof, comprises two clamping plates (10, 20). a threaded fastener (1) coupling the plates together, half-shell clamping parts (11, 21) for fixing the device to at least one reinforcing rod, and a further plate (7) for fixing an earthing cable (4) to plate (10) by means of a locking screw (5). Accompanied by simultaneous reciprocal bracing, the two clamping plates (10, 20) are fixed to e.g. crosswise arranged iron reinforcing bars or rods (3a, 3b), with reciprocal engagement in three areas (A, B, C) thereby ensuring a good clamping action. <IMAGE>

Description

TERMINAL DEVICE FOR CONNECTING ELECTRICAL CONDUCTORS The invention relates to a terminal device for shunting earth currents of electrical installations in a building having metal reinforcing rods in the foundation thereof.

It is known to connect earthing cables of electrical installations and antennas by means of pipe clips to the water mains of buildings. However, a completely satisfactory earthing is no longer obtained as a result of the use of plastics pipes and fittings for water mains and greatly improved seals, also in metal pipe systems. In addition, leakage currents in underground cast iron or steel pipes can further corrosion, which can lead to pipe fracture.

As a result of technical developments, new buildings contain a large number of pipes and lines because, apart from extensive water, gas and heavy current installations, there are also central heating, antenna (radio) and telephone systems. Together they form a branched network of metal systems, which are engaged in one another, are partly separated from one another and are partly (directly or indirectly) joined. Therefore errors or deficiencies in one system can have unfavourable effects on another system.

In order to achieve increased protection against shockhazard voltages if these and other deficiencies occur with respect to pipe systems, a main potential equalization is required, which interconnects all the metal systems used.

This main potential equalization is made much more effective through earth rods introduced into the foundation of the building and lighting protection systems can also be connected thereto.

It is therefore proposed in connection with building projects, that the earthing cable or cables are joined to the reinforcing iron members located in the foundations.

However, the hitherto known terminals are either not suitable for this purpose of are not usable for the different connection possibilities involved.

The present invention has been developed primarily, though not exclusively, with a view to provide a robust terminal device of the aforementioned type, by means of which a durable and reliable connection of earthing cables with reinforcing rods located in building foundations is ensured, the terminal device being constructed in an easy to assemble manner.

According to the invention there is provided an electrical terminal device for shunting earth currents of electrical installations in a building having metal reinforcing rods in the foundation thereof, the device comprising: two clamping plates; a threaded fastener coupling the plates together; means for fixing the device to at least one reinforcing rod; a flange provided on one of said clamping plates for fixing an earthing cable; and means for fixing the earthing cable to said flange.

Embodiments of electrical terminal device according to the invention will now be described in detail, by way of example only, with reference to the accompanying drawings: Figure 1 is a side view of a first embodiment; Figure 2 is a plan view of Figure 1; Figure 3 is a plan view of a second embodiment; Figure 4 is a side view of a third embodiment; and, Figure 5 is a plan view of Figure 4.

The terminal device shown in Figures 1 and 2 has an upper clamping plate 10 and a lower clamping plate 20.

Each clamping plate 10, 20 has a clamping part 11 or 21 constructed as a half-shell and a plate part 12 or 22.

Plate part 12 of upper plate 10 is rectangular and is wider than the length of clamping part 11 arranged centrally thereto.

Plate part 12 has a recess 13 which widens conically towards the end thereof and whose width approximately corresponds to the width of clamping part 11, so that on either side of recess 13 separate bearing surfaces 14 are formed. In addition, the upper clamping plate 10 has a through hole 15 and a threaded hole 16.

Plate part 22 of the lower clamping plate 20 is shorter than plate part 12 and has a T-shaped construction, as can in particular be seen from Figures 4 and 5. The Tshape is formed by a web 26 and two lugs 25 laterally fixed thereto, the width of web 26 corresponding to the length of clamping part 21. Between the two lugs 25 is provided a recess 23 which widens conically towards the plate end, so that raised bearing surfaces 24 are formed on lugs 25.

The lower clamping plate 20 has a threaded hole 27 corresponding to the through hole 15 and an approximately semicircular recess 28, which prevents rotation of the two plates in the assembly position (Figures 4 and 5).

According to Figures 1, 2 and 3, the two clamping plates 10, 20 are reciprocally fixed together by means of a screw 1 and simultaneously connected to two crossing iron bars 3a, 3b. Screw 1 is prevented from loosening by means of a clamping disk 2. Iron bars 3a, 3b are e.g. the reinforcing rods of a concrete foundation.

For fixing purposes the two clamping plates 10, 20 are superimposed in such a way that clamping parts 11, 21 are at right angles to one another. According to Figures 2 and 3 two different positions for crossing reinforcing bars are possible. As a result of the corresponding short construction of clamping parts 11 and 21 at the crossing part iron bars 3a, 3b are not covered by the clamping plates, so that clamping is not impeded by any connecting wire fitted there for fixing the iron bars 3a, 3b.

On fixing a so-called "three-point contact" is formed in three areas A, B and C between the two clamping plates or between the clamping plates and the iron bars 3a, 3b.

Following the clamping of the clamping plates, an earthing cable 4 is fixed by means of a flange 7 and a locking screw 5 with locking disk 6 to the upper clamping plate 10, screw 5 being screwed into the threaded hole 16. Flange 7 is constructed in such a way that on one side of the locking screw it engages with a semi-circular recess 7a on earthing cable 4 and on the other side of the locking screw with two projections 7b on clamping plate 10.

According to Figures 4 and 5 the two clamping plates 10, 20 can be superimposed in such a way that the clamping parts are directed against one another and are parallel to one another. Thus, two superimposed iron bars 3c and 3d can be secured, so that there is also a three-point contact through areas D, E and F.

In all the assembly variants, this leads to a completely satisfactory clamping action with good metal contact for the shunting of electric currents, screw 1 always being accessible for tightening purposes.

Claims

1. An electrical terminal device for shunting earth currents of electrical installations in a building having metal reinforcing rods in the foundation thereof, the device comprising: two clamping plates; a threaded fastener coupling the plates together; means for fixing the device to at least one reinforcing rod; a flange provided on one of said clamping plates for fixing an earthing cable; and means for fixing the earthing cable to said flange.

2. An electrical terminal device according to Claim 1, in which each clamping plate has a clamping part shaped like a half-shell for receiving the respective reinforcing rod, and a plate part, and being provided with individual bearing surfaces by a shaped-on recess.

3. A terminal device according to Claim 1 or 2, in which the two clamping plates are fixable together with respective clamping parts extending either parallel or at right angles to one another, thereby to be fixable to parallel reinforcing rods or to transversely extending reinforcing rods.

4. A terminal device according to Claim 3, in which the two clamping plates are fixable to one of the four corners of transversely crossing reinforcing rods, and are fixable together by means of a freely accessible screw.

5. A terminal device according to any one of the preceding claims, in which the threaded fastener comprises a threaded bolt or screw, and said means for fixing the earthing cable comprises a locking bolt or screw, and in which one of said clamping plates has a through hole for receiving said threaded bolt or screw and a threaded hole for receiving said locking bolt or screw, and the other clamping plate has a threaded hole for receiving said threaded bolt or screw and at least one recess for said locking bolt or screw.

6. A terminal device according to any one of the preceding claims, in which the two clamping plates are clampable together engaging in three areas or points.

7. A terminal device according to any one of the preceding claims, in which said flange can be braced to engage in three areas.

8. A terminal device according to Claim 1 and substantially as hereinbefore described with reference to, and as shown in any one of the embodiments illustrated in the accompanying drawings.