GB2431012A

GB2431012A - Electrical test lead

Info

Publication number: GB2431012A
Application number: GB0520300A
Authority: GB
Inventors: David Harris
Original assignee: KEW TECHNIK Ltd
Current assignee: KEW TECHNIK Ltd
Priority date: 2005-10-06
Filing date: 2005-10-06
Publication date: 2007-04-11
Also published as: GB0520300D0

Abstract

The invention relates to an electrical lead 1. Lead 1 comprises a cable having an earth, live (positive) and neutral (negative) wire (20,40,30), means to connect one end of the cable to a tester X, and a tail body (41,31) on each of said live and neutral wires at the other end of the cable, each tail body having a connector (42,32) to engage and disengage with a head, the tail body on the live and/or neutral wire incorporating a fuse (45,35) between the connector and the wire. A plurality interchangeable heads (43,44 and 33,34) are provided for the tails. A tail body 21 with a head 23 is provided on the earth wire 20. In use connection to either side of a fuse being unbroken when a head is engaged or disengaged from a tail body. Also, the neutral and earth tail bodies may be readily releasably connected. Also, the tail bodies may connect to a mains plug adaptor for mains socket testing. The electrical test lead can be used to perform Earth Loop Impedance, Ze or PFC tests at electricity mains sockets, light fittings and/or distribution boards.

Description

Title: Electrical Lead The present invention relates to an electrical

lead, and especially to a lead which can be used in "Earth Loop Impedance" tests through ring main sockets and lighting ring fittings, PFC tests and Ze tests through a distribution board.

It is known to provide a tester which plugs into a socket to check the earth loop impedance in a ring main.

It is also known to provide a tester which has a lead extending therefrom with Earth, Positive and Negative wires. The ends of the wires remote from the tester each include a tail which can receive a head either in the form of a crocodile clip or probe. The probes are used to test earth loop impedance in lighting rings, and the crocodile clips are used to clip onto a distribution board to do PFC tests and Ze tests.

To do all these tests, two testers are required.

Also when doing the PFC test, the jaws of the "earth" crocodile clip needs to be clamped onto the jaws of the negative" crocodile clip or vice versa, and one of the jaws then needs to clamp onto a bar on the distribution board. This can lead to poor connections and false readings.

Also a fuse is usually present between the head and tail, and when a head is changed over (e.g. a crocodile clip head is replaced with a probe head) the fuse can fall out arid frequent changing of the heads can cause the contacts across the fuse to form a bad connection giving a false reading on the tester.

The invention seeks to provide an electrical lead for use with a tester which allows a singe tester to be used for all the above mentioned tests and avoids the problems with known heads and fuses.

According to a first aspect of the present invention there is provided an electrical lead comprising: a) a cable having an earth, positive and negative wire, b) means to connect one end of the cable to a tester, c) a tail body on each of said positive and negative wires at the other end of the cable, each tail body having a connector to engage and disengage with a head, the tail body on the positive and/or negative wire incorporating a fuse between the connector and the wire, and d) a plurality interchangeable heads for the tails, and e) a tail body with a head on the earth wire, in use connection to either side of a fuse being unbroken when a head is engaged or disengaged from a tail body.

Preferably probe heads and crocodile clip heads are provided for the tail body on each of said positive and negative wires.

The tails body on the earth wire may have an integral or removable head. The earth wire tail body head may be a crocodile clip.

The earth wire tail body may be adapted to releasably connect with the negative wire tail body or vice versa. Preferably the negative wire tail body connector engages and disengages with the earth wire tail body.

Preferably a housing is further provided with earth negative and positive fingers to engage into a plug socket, said housing having connector means to releasably engage with the earth positive and negative tail connectors to connect the earth positive and negative wires to the earth negative and positive fingers.

Connectors between heads and tails and tails and tails may be 4mm plugs and sockets. The plugs may be provided on the tails to insert into sockets on the heads.

According to a second embodiment of the invention there is provided an electrical lead comprising: a) a cable having an earth, positive and negative wire, b) means to connect one end of the cable to a tester, c) a tail body on each of said positive and negative wires at the other end of the cable, each tail body having a connector to engage and disengage with a head, e) a tail body with head on the earth wire, the earth wire tail body being adapted to releasably connect with the negative wire tail body or vice versa.

Features of the second embodiment may be combined with any one or more of the features of the aforementioned first embodiment.

An embodiment of the invention will now be described with reference to the accompanying drawing showing a schematic perspective view.

Referring to the drawing there is shown an electrical lead I. Lead I includes a cable 10 having an "earth" wire 20, "negative" wire 30, and a "positive" wire 40. One end IOA of cable 10 is connected to a circuit tester "X" of a type well known in the art and need not be described herein.

The other end lOB of cable 10 exposes the three wires 20,30,40.

A tail body 41 is provided on the end of positive wire 40 having a male connector in the form of a shrouded 4mm plug 42 to engage with the female 4mm socket of either a crocodile clip head 43 or probe head 44. An internal fuse 45 is provided in the tail body 4! between the plug 42 and the wire 40 so that connection to either side of the fuse remains unbroken when a head 43 or 44 is engaged or disengaged from a tail body 41.

A tail body 31 is provided on the end of negative wire 30 having a male connector in the form of a shrouded 4mm plug 32 to engage with the female 4mm socket of either a crocodile clip head 33 or probe 34. An internal fuse 35 is provided in the tail body 31 between the plug 32 and the wire 30 so that connection to either side of the fuse remains unbroken when a head 33 or 34 is engaged or disengaged from a tail body 31.

A tail body 21 is provided on the end of earth wire 20 having a male connector in the form of a shrouded 4mm plug 22 to engage with the female 4mm socket of a crocodile clip head 23. If desired head 23 could be integral with tail body 21. Tail body 2! further includes a female 4mm socket 25 to receive 4mm plug 32.

A housing 50 is further provided with an earth finger 51, negative finger 52 and positive finger 53 to engage into a plug socket. Connector means in the form of female sockets 54, 55 and 56 releasably engage with the earth positive and negative male plugs 22,32, and 42 respectively to connect the earth positive and negative wires 20,30,40 to the earth negative and positive fingers 51,52,53.

In use tester "X" can be used to perform an earth loop impedance test on a ring main by inserting the housing 50 fingers into an electrical socket and connecting the female sockets 54, 55 and 56 to releasably engage with the earth positive and negative male plugs 22,32, and 42 respectively to connect the earth positive and negative wires 20,30,40 to the earth negative and positive fingers 5 1,52,53.

Tester "X" can be used to perform an earth loop impedance test on a lighting ring by connecting the females sockets of probe heads 34,44 with plugs 32,42 and holding the probe heads onto negative and positive lighting terminals and crocodile clip 23 onto any suitable metal light casing or other "earth" point.

Tester "X" can be used to perform a Ze test by connecting female sockets of crocodile heads 33,43 with plugs 32,42, and clamping the crocodile heads 23,33,43 onto earth, negative and positive contacts on a distribution board.

Tester "X" can be used to perform a PFC test by connecting females socket of crocodile head 43 with plug 42, connecting tail body female socket 25 with plug 32, and clamping the crocodile heads 23,43 onto negative and positive contacts on a distribution board.

It will be appreciated that by using the lead of invention, the tester "X" can be used for different tests.

The invention may take a form different to that specifically described above. For example the negative wire tail body 31 could have a female socket to receive the earth wire tail body plug 22 to join the earth and negative wires for PFC tests.

The invention could also comprise in a broad aspect of a lead without the fuses, but with the the earth wire tail body being adapted to receive the negative wire tail body or vice versa.

Thus according to a second embodiment of the invention there is provided an electrical lead comprising: a) a cable having an earth, positive and negative wire, b) means to connect one end of the cable to a tester, c) a tail body on each of said positive and negative wires at the other end of the cable, each tail body having a connector to engage and disengage with a head, e) a tail body with head on the earth wire, the earth wire tail body being adapted to releasably connect with the negative wire tail body or vice versa.

Further modifications will be apparent to those skilled in the art without departing from the scope of the present invention.

Claims

1. An electrical lead comprising: a) a cable having an earth, positive and negative wire, b) means to connect one end of the cable to a tester, c) a tail body on each of said positive and negative wires at the other end of the cable, each tail body having a connector to engage and disengage with a head, the tail body on the positive andlor negative wire incorporating a fuse between the connector and the wire, and d) a plurality interchangeable heads for the tails, and e) a tail body with a head on the earth wire, in use connection to either side of a fuse being unbroken when a head is engaged or disengaged from a tail body.

2. An electrical lead according to claim I, wherein probe heads and crocodile clip heads are provided for the tail body on each of said positive and negative wires.

3. An electrical lead according to claim I or 2, wherein the tail body on the earth wire may have an integral or removable head.

4. An electrical lead according to claim 1, 2 or 3, wherein the earth wire tail body head is a crocodile clip.

5. An electrical lead according to any preceding claim, wherein the earth wire tail body may be adapted to releasably connect with the negative wire tail body or vice versa.

6. An electrical lead according to any preceding claim, wherein the negative wire tail body connector engages and disengages with the earth wire tail body.

7. An electrical lead according to any preceding claim, wherein a housing is further provided with earth negative and positive fingers to engage into a plug socket, said housing having connector means to releasably engage with the earth positive and negative tail connectors to connect the earth positive and negative wires to the earth negative and positive fingers.

8. An electrical lead according to any preceding claim, wherein connectors between heads and tails and tails and tails may be 4mm plugs and sockets.

9. An electrical lead according to claim 8, wherein the plugs may be provided on the tails to insert into sockets on the heads.

10. An electrical lead comprising: a) a cable having an earth, positive and negative wire, b) means to connect one end of the cable to a tester, c) a tail body on each of said positive and negative wires at the other end of the cable, each tail body having a connector to engage and disengage with a head, e) a tail body with head on the earth wire, the earth wire tail body being adapted to releasably connect with the negative wire tail body or vice versa.

11. An electrical lead according to claim 10, wherein the tail body on the positive and/or negative wire incorporates a fuse between the connector and the wire.

12. An electrical lead according to claim 11, wherein in use connection to either side of a fuse is unbroken when a head is engaged or disengaged from a tail body.

13. An electrical lead according to claim 10,11 or 12, further comprising a plurality of interchangeable heads for the tails.

14. An electrical lead according to any of claims 10 to 13, wherein probe heads and crocodile clip heads are provided for the tail body on each of said positive and negative wires.

15. An electrical lead according to any of claims 10 to 14, wherein the tail body on the earth wire may have an integral or removable head.

16. An electrical lead according to any of claims 10 to 15, wherein the earth wire tail body head is a crocodile clip.

17. An electrical lead according to any of claims 10 to 16, wherein the earth wire tail body may be adapted to releasably connect with the negative wire tail body or vice versa.

18. An electrical lead according to any of claims 10 to 17, wherein the negative wire tail body connector engages and disengages with the earth wire tail body.

19. An electrical lead according to any of claims JO to 18, wherein a housing is further provided with earth negative and positive fingers to engage into a plug socket, said housing having connector means to releasably engage with the earth positive and negative tail connectors to connect the earth positive and negative wires to the earth negative and positive fingers.

20. An electrical lead according to any of claims 10 to 19, wherein connectors between heads and tails and tails and tails may be 4mm plugs and sockets.

21. An electrical lead according to claim 20, wherein the plugs may be provided on the tails to insert into sockets on the heads.

22. An electrical lead substantially as hereinbefore described with reference to and as shown in the accompanying drawings.