Connectors

It is often necessary to join cables together . In the wiring of buildings this is rarely done by soldering . Good soldered joints can be made in factory conditions , but thew conditions existing on a building site , and the quality of work that can be done under such conditions , are such that joints may not be sufficiently reliable . Also , the time takien to make them would put up the cost of the electrical service considerably . Crimping the cables is a more cost-effective method of jointing cables ; this is achieved by squeezing special lugs onto the cable conductor by means of a special tool . It is also common practice to join cables by means of connector blocks , which require olny mechanical terminations to the cables . A connector nlocks is illustrated in Figure 1.21 . It consists of two screw-down-type terminals solidly connected to each other , mounted in an insulated casing . The end of each cable is pushed into one of the terminals , with the insualtion taken up to the connector , with no bare conductor visible , and the screw is tightened on to it . The screw grips the conductor , holding it firmly in place and at the same time making a good electrical contact . As the two terminals are solidily connected within the insulated case , the result is that there is a good electrical path between the two cables . Joints and terminals made in this way must be available for inspection . In addition to this , all joints and terminations must be enclosed within a non-combustible material . Therefore , any accessory without an appropriate back plate must not be fixed to a combustible surface such as wooden partition , without the use of a pattress . A joints or termination made by welding , brazing , soldering , crimping , or encapsulating need not be available for inspection .
  With such connector blocks , it is possible to join cables neatly within the boxes which have already been described . In general , joints should be avoided and single length of cable run from one piece of equipment to another , but when an occasion arises when this cannot be done , connector blocks may be used .
  The author has tried in this chapter to give a survey of the more important accessories and to give an idea of the wide range available . It is not possible to descrie every accessory made ; a full knowledfer can be obtained olny by a study of many accessory made ; a full knowledge can be obtained olny by a study of many manufacturers's catalogues  and , preferably , by the use of the accessories on actual sites