GB2466941A

GB2466941A - Consumer unit for housing residual current devices and miniature circuit breakers

Info

Publication number: GB2466941A
Application number: GB0823595A
Authority: GB
Inventors: Keith John Whitman
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-12-29
Filing date: 2008-12-29
Publication date: 2010-07-21
Also published as: GB0823595D0

Abstract

A consumer unit or distribution board for an electrical power supply, comprises a housing 10, including an inlet means to enable a live 10a and a neutral 10b electric cable to enter the unit, and live 22 and neutral 23 busbars connected to the live and neutral cables. A mounting means e.g. DIN rail 18, is provided to retain safety switching elements 15-17, where the safety elements are connectable, when mounted to the mounting means, to the live and neutral busbars. Each safety elements may be a MCB (Miniature Circuit Breaker) and may also include a Residual Current Device (RCD), e.g a RCBO (Residual Current Breaker with Overload). Each busbar may have a connection socket 24, 25 to enable the connection of the safety elements. A main switch 11 may be provided. The DIN rail may be earthed 19.

Description

AN IMPROVED ELECTRICAL CONSUMER UNIT

Field of the Invention

The present invention relates to a consumer unit, applicable for use in a domestic environment, said consumer unit housing residual current devices and miniature circuit breakers.

Background to the Invention

The electrical wiring within buildings is subject to increasingly stringent regulations pertaining to safety. Previously little attention was paid to this area beyond the provision of fuses, often in the form of a simple wire element, which fuses reacted to a too high flow of current. This not only made fuses a relatively blunt instrument but often caused problems in replacing "blown" fuses; for example in ensuring that the right fuse was, correctly fitted, often in cramped conditions. Moreover, fuses do not always provide sufficient protection or an indication of where current leakage to earth is occurring.

Physical fuses as described above have been largely replaced by, especially in domestic environments, miniature circuit breakers (MCBs). MCBs are designed to operate when the current flowing in a particular circuit exceeds a predetermined value. On said value being breached, the MCB acts to break the circuit and prevent flow of current. By this means a wiring circuit will not be subjected to a damaging current.

In addition, modern circuits are protected by residual current devices (RCDs).

RCDs act to measure any leakage of current to earth. Such leakage can simply indicate a fault in the equipment being supplied. However, of greater importance is the protection of an individual from being electrocuted. In the event of a person touching a live wire to a device such that a current can flow through that person to earth, then an imbalance is caused in the current flowing into a device compared with that flowing out of the device. This results in the RCD breaking the circuit to that device.

As a further type of protection should be mentioned an RCBO, which combines the overcurrent and the earth leakage facility in one unit. This is often achieved simply through combining together an MCB with an RCD.

The above alternatives and improvements to fuses bring not only advantages in respect of increased functionality but also ease of restoration of power supply, as with the latter devices this usually requires simply a switch to be set back to the "on" position.

As indicated above, new regulations on safety are regularly brought into effect.

Recently in the United Kingdom, the 17th edition of BS7671 has come into force which requires, amongst other things, for RCD protection to be applied to virtually all circuits.

To reach this target two methods have so far been employed. The first method is to employ a dual RCD board containing two RCDs together with a number of MCBs. The second method is to employ a mains' switch Consumer Unit consisting of RCBOs.

The problem with the first method is that if an earth leakage fault develops in any of the outgoing circuits, the RCD trips and removes power from all the circuits into which that particular RCD is linked. In the event that the lighting circuits are linked to the RCD then an additional hazard is brought about for anyone trying to determine the origin of the fault and repair. Moreover, the boards on which the elements of the RCDsJMCBs are mounted, are usually much bigger than conventional fuse boxes, which leads to problems of installation.

The second method, utilising RCBOs in all outgoing circuits suffers from the disadvantages of the RCBOs being expensive and also from a congestion of wires within the Consumer Unit.

It is therefore an object of the present invention to provide a consumer unit which seeks to address the above difficulties.

Summary of the Invention

According to a first aspect of the invention there is provided a consumer unit for an electrical supply, the unit comprising a housing, the housing being adaptable to be mounted on a wall or other such surface and including inlet means to enable a live and a neutral electric wire or cable to enter the unit, retaining means to hold the wires firmly in position, a first elongate conducting element connectable to the live wire, a second elongate element connectable to the neutral wire; a mounting means to receive one or more safety elements and retain said safety elements in the required position, the or each safety elements being incorporated into and monitoring current within a circuit and adapted to break the circuit if the current exceeds a preset level or on earth leakage, the safety elements being connectable, when mounted to the mounting means, to the first and second elongate element.

The invention allows a circuit to be reinstated after repair in the event of a problem and also for easy replacement of a safety element when required.

Preferably, the or each safety element includes a circuit breaker, said circuit breaker being especially preferably a miniature circuit breaker.

Optionally, the or each safety element includes a residual current device to determine cunent leakage in a circuit.

Advantageously, the safety element includes a residual current breaker with overcurrent protection.

The unit advantageously comprises two or more second elongate elements enabling the unit to serve separate but related electrical areas.

Brief DescrEption of the Drawings The invention will now be described with reference to the accompanying drawing which shows by way of example only one embodiment of a unit. In the drawing: Figure 1 illustrates an open consumer unit, a front cover having been removed from the unit.

Detailed Description of the Invention

The invention as herein described is suitable for use in both the domestic and the industrial environment and enables a safe and effective control of the electric supply to a given area to be maintained. In the event of a problem with an electrical item within a circuit, the offending item can be readily identified, repaired or replaced and the power supply resumed. The unit is suitable for use in confined spaces as the parts within the unit can be readily handled or replaced.

Moreover, the size of the enclosure can be smaller than conventionally required with a resultant cost and space saving.

In prior art units, the incorporation of both an RCD and a MCB would lead to a large amount of cabling which is both difficult to organise into a compact unit and which can also be complicated when repairs or replacements are required, during which a wire needs to be traced to its source.

In order to achieve the above, the Consumer unit according to the present invention includes a series of elements each corresponding to a particular electrical current being supplied, which in one embodiment can be simply plugged into position without the need for individual wires to be secured. This represents a time saving to the user.

Referring to Figure 1, this illustrates an opened consumer unit. The unit is designed to be fixed to a wall or other surface of a building in an accessible location. The elements of the unit are housed within a casing 10, the front cover of which has been removed in Figure 1 for illustrative purposes. In use, the cover ensures that accidental contact with the current carrying wires is precluded.

The cover does however have apertures to allow operation of the mains switch 11 and RCBO switches 12, 13, 14. Electric current is supplied to the unit by means of the mains' live and neutral wires lOa, lOb respectively.

In order to control the current in a circuit the unit includes a number of RCBOs, 15, 16, 17 which detect both overcurrent and current earth leakage. In the illustrated unit, the circuits of different ampage are grouped together with RCBOs 15, 16, 17 being rated for 30A, 16A and 6A respectively. The number and rating will of course depend on the usage and the circuit rating within the building. Each RCBO 15, 16, 17 has mounting means such as clips or lugs which enable the RCBO to be fixed or removed easily from a Din rail 18 which spans the width of the casing 10. For increased safety, the Din rail 18 is earthed by means of the earth wire 19 secured thereto.

In addition each RCBO has a live and a neutral wire 20, 21 which link into the particular circuit the RCBO is monitoring and protecting. Linkage is facilitated in the present invention by two bus bars 22, 23, held in parallel spaced relationship with the bus bar 22 being live and the bus bar 23 neutral. Insulating material can be provided between the two bus bars 22, 23.

Each bus bar 22, 23 has a series of connection sockets 24, 25 which enable an RCBO having the corresponding plug to be plugged into the bus bars 22, 23. In addition each RCBO has a fitment complementary in shape to that of the Din Rail 18 enabling the RCBO to be housed on the Din Rail 18 when so connected.

An individual RCI3O can therefore be easily removed or added simply by locating in position, and the need to connect wires individually is removed. As a consequence of the self containment of the system occasioned by the use of a neutral bus bar 23, the number of wires housed within the free space of the unit is reduced. Moreover due to the compact and tidy arrangement afforded on the inside of the unit, fault finding and repair time is minimised.

In use therefore, in the event of a fault occurring within a particular circuit, the RCBO associated with that circuit trips to the off position. If the fault is simple to rectify then the cause can be isolated or repaired and the circuit reinstated by moving the switch to the "on" position. In the event that the RCBO needs to be replaced due to its no longer functioning properly, then a mains' switch can be switched off, and the RCBO simply unplugged from the bus bar and removed from the Din rail. A replacement RCBO can be easily fitted into position and the mains' switch switched on again. Fitment and removal can be facilitated by means of conventional spring loaded clips known in the art. The time taken to perform this action is less than would normally be the case with a reduction in cost and inconvenient to the user.

It will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the invention.

Claims

CLAIMS1. A consumer unit for an electrical supply, the unit comprising a housing, the housing being adaptable to be mounted on a wall or other such surface and including inlet means to enable a live and a neutral electric wire or cable to enter the unit, retaining means to hold the wires firmly in position, a first elongate conducting element connectable to the live wire, a second elongate element connectable to the neutral wire; a mounting means to receive one or more safety elements and retain said safety elements in the required position, the or each safety elements being incorporated into and monitoring current.within a circuit and adapted to break the circuit if the current exceeds a preset level or on earth leakage, the safety elements being connectable, when mounted to the mounting means, to the first and second elongate element.
2. A consumer unit according to Claim 1, wherein the or each safety element includes a circuit breaker.-
3. A consumer unit according to Claim 2, wherein the circuit breaker is aS* miniature circuit breaker.*...*S * SSS
4. A consumer unit according to any preceding claim, wherein the or eachSSsafety element includes a residual current device to determine current leakage in a circuit.S S.

S
5. A consumer unit according to any preceding claim, wherein the safety element includes a residual current breaker with overcurrent protection.
6. A consumer unit according to any preceding claim, wherein the consumer unit comprises two or more second elongate elements.
7. A consumer unit substantially as herein described with reference to the accompanying drawings.S -S *SSS* * SS * * . 25 * ** * S * * **I *SI * I