joints and accessories IEE regulations on joints and terminations Types of terminals Types of joints Cable soldering methods

1. 1
CABLES AND CONDUCTORS
joints and terminations

2.  joints and accessories
 IEE regulations on joints and terminations
 Types of terminals
 Types of joints
 Cable soldering methods
2
CONTENT

3.  Joint
 The connection of two lengths of conductors by a method which ensures a
continuous path for the unimpeded flow of an electrical current
 Termination
 Applied t o the end of a conductor prepared in such a way that it is suitable for
connection to the terminal to which it is to be connected by mechanical means
 Basic electrical and mechanical requirements for joints and terminations
I. There must be sufficient contact area between the two current carrying surfaces
(e.g. between wire and terminal) this is ensures that heat is not generated on such
surfaces on account of increased resistance
II. There must be adequate mechanical strength this will avoid cables form being pulled
apart
III. Should be easy to connect and disconnect electrical joints are made permanent by
crimping or soldering
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JOINTS AND TERMINATION

4. IEE REGULATIONS ON JOINTS &TERMINATIONS
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 1. - All joints must be durable, adequate for their purpose, and
mechanically strong.
 2. - They must be constructed to take account of the conductor
material and insulation, as well as temperature: e.g., a soldered
joint must not be used where the temperature may cause the
solder to melt or to weaken. Very large expansion forces are not
uncommon in terminal boxes situated at the end of straight runs
of large cables when subjected to overload or to fault currents.
 3. - All joints and connections must be made in an enclosure
complying with the appropriate British Standard.
 4. - Where sheathed cables are used, the sheath must be
continuous into the joint enclosure
 5. - All joints must be accessible for inspection and testing unless
they are buried in compound or encapsulated, are between the
cold tail and element of a heater such as a pipe tracer or under
floor heating system, or are made by soldering, welding, brazing
or compression.

5. JOINTS AND TERMINATION
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 Joint Making Methods
 The many methods use to join conductors may be reduced to two
definite groups
 The first group involves the use of heat to fuse together the surfaces
o the joints (e.g. soldering and welding)
 The second group uses pressure and mechanical means to hold the
surfaces together (e.g. soldering and welding )
 Soldering
 soldering is defined as "the joining of metals by a fusion of alloys
which have relatively low melting points. Consider that soldering is
more like gluing with molten metal
 The metal used for joining copper surfaces is Solder, which is an
alloy of tin and lead. It melts at comparatively low temperatures.
 The disadvantage of soldering joints it makes them non separable
 Soldered joints in bus bars must be reinforced by bolts and clamps

6. JOINTS AND TERMINATION
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 WELDING
 Welding is the joining of two metal surfaces by melting adjacent
portions so that their is definite fusion between them to an
appropriate depth. The heat supplied is from an electric arc or a
gas torch
 The welded joint is a non separable contact
 This process is sometimes used for large sections conductors such
as busbars .
 CLAMPING
 A clamped joint is easy to make no particular preparation being
required. The effective cross-sectional area of the conductor is
not affected though the extra mass of metal round the joint of
termination makes a larger bulk. However the joint or
termination is cooler in operation. This method provides a
separable contact. Surfaces must be clean and in definite
mechanical contact. Precautions must be taken to make sure that
the bolts and nuts are locked tight.

7. JOINTS AND TERMINATION
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 BOLTING
 This method involves drilling or punching holes in materials and
more suitable for busbars. The holes tend to reduce the effective
area of the material. Contact pressure also tends be less
uniformly distributed in a bolted joint than in one held together
by clamps. Bolted joints can be dismantled easily.
 RIVETING
 If well-made riveted joints make good connection. There is the
disadvantage that they cannot be easily be undone or tightened
in service
 CRIMPING
 Joints his is a mechanical method for conductor joints, a closely
fitting sleeve is placed over the conductors to be joined together
and crimped together or squeezed together by a hydraulic or
pneumatically – operated crimping tool. Crimped lugs are also
available for conductor terminations

8. TYPES OF TERMINALS
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 There is a wide variety of
conductor terminals typical
methods include
 1. Pillar terminal
 a pillar terminal is a brass pillar
with a hole through its side which
the conductor is inserted and
secured with a screw
 If the conductor is small in
relation to the hole it should be
doubled back
 When two or more conductors
are to to go through the same
hole they should be twisted
together
 Care should be taken not to
damage the conductor by
excessive tightening

9. TYPES OF TERMINALS
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 2. Eyelet terminal
 Using round nosed pliers form
conductors end into an eye
slightly larger than the screw
shank but smaller than the outer
diameter of the screw head nut or
washer.
 The eye should be placed in such a
way that rotation of the screw
head or nut tends to close the
joint in the eye
 Claw washers
 Claw washers are used to get a
better connection. Lay the looped
conductor in the pressing
 Place a plain washer on top of the
loop and squeeze the metal flat
using the right tool

10. TYPES OF TERMINALS
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 3. Strip Connectors
 Conductors are clamped by brass
grab screws in the connectors
mounted in a molded insulated
block.
 The conductors should be inserted as
far as possible into connector so that
pinch screw clamps the conductor.
 A good clean, tight termination is
essential in order to avoid high
resistance contacts resulting in
overheating of the joint.
 4. Lugs
 Lugs are made from tinned solid
copper or aluminum. Used
extensively in electrical contracting
industry for terminating cables
 They are fastened to cable ends by
crimping

11. TYPES OF JOINTS
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 Scarf joint
 This is one of the simplest joints to make and is used where the wires
are not under any tensile stress and also where the joint is to be small as
possible. Though generally used with solid conductors, it can be used on
stranded conductors provided they are soldered solid before hand
 Method
I. The end of each conductor is chamfered by carefully filling for 40mm
II. Clean the ends tin them and fit them together so that the joint length
diameter is the same as the un cut conductor
III. Hold the conductors together and bind the joint with tinned binding
wire over a distance of 65mm
IV. Solder the joint. Wipe off any excess solder with a fluxed cloth pad

12. DIAGRAM OF SCARF JOINT
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13. TYPES OF JOINTS
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 Britannia joint
 This joint is used for single overhead copper conductors which are
not under tension
 Method
I. Thoroughly clean the ends of the conductors
II. Tin the ends for a distance of about 75mm
III. Bend 6mm of each end over at right angles. This prevents the
joint from pulling out when in use
IV. Bring the two wires together side by side over a distance of
about 50mm. the ends should face opposite directions
V. Hold the joints in a small vice or with pliers
VI. Bind both conductors together 1.00mm2 tinned copper binding
wire the binding should be carried about 6mm (about five turns
past each conductor end)
VII.Solder the joint (the whole length of the binding) Wipe off any
excess solder with a fluxed cloth pad

14. BRITANNIA JOINT
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15. TYPES OF JOINTS
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 Bell hangers joint / western union
 This joint at times is also called straight twist joint it is not a strong type
and so it is used where more tensile stress is placed on the conductors
which are usually solid core and insulated
 Method
I. Remove the insulation from each conductor and for a distance of
about 75mm
II. Clean the ends
III. If VRI cable strip off the braiding and tape for a further 12mm on each
conductor
IV. Lay the conductors together about 50mm from the ends. Twist them
tightly round each other in opposite directions. Each turn of a
conductor should fit closely to the next turn. Pliers can be used to grip
the crossed the conductors. Each twist should contain about six turns
V. Cut off surplus conductor ends on the bevel with side cutters smooth
over with pliers
VI. Wipe off any excess solder with a fluxed cloth pad make good the
removed insulation

16. TYPES OF JOINTS
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 Bell hangers/
straight twist joint

17. TELEGRAPH JOINT
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 Telegraph joint
 This joint is not strong and is generally used for single core insulated
conductors
 Method
I. Remove the insulation from each end for a distance of about 100mm
II. Clean and tin the ends
III. If VRI cable, strip off the braiding and a tape for a further 12mm on each
conductor
IV. Cross the conductors about 30mm from the insulation keeping the left-hand
conductor in front
V. Using pliers grip the crossed conductors together
VI. Twist the left hand end and the right hand main portion together. This turns
need not to be sharp
VII. Twist the right-hand end and the left hand main portion together
VIII.Cut off surplus conductor ends on the bevel with side cutter smooth over
with pliers
IX. Solder the joint. Wipe off any excess solder with a fluxed cloth pad
X. Make good the insulation removed

18. TYPES OF JOINTS
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 Telegraph / American twist joint

19. TEE TWIST JOINT
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 Tee Twist Joint
 This is a branch or TEE joint made with single core conductors
 Method
I. Remove insulation from through piece a distance of 50mm in the center.
This wire must not be cut
II. If VRI cable, strip off the braiding and tape for a further 12mm at each side
III. Remove the insulation from the tee piece for a distance of about 75mm
from the end
IV. If VRI cable strip off the braiding and tape for a further 12mm
V. Clean the bare conductors if necessary
VI. Place the tee piece at right angles to the left hand side of the bared
through piece and tightly bind round the through conductor from left to
right
VII. Cut off surplus conductor end on the bevel with side cutters and smooth
over with pliers
VIII.Solder the joint leaving two or three turns free for flexibility
IX. Wipe off any excess solder with a fluxed cloth pad
X. Make good the insulation removed

20. TEE TWIST JOINT
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 Tee Twist Joint / Aerial Tap

21. TYPES OF JOINTS
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 Straight Married joint
 The married joint is made with stranded conductors
 When made correctly it forms a very strong and satisfactory joint
 Method (three stranded conductors )
I. Remove insulation for about 75mm from each conductor
II. If VRI strip of and tape a further 12mm on each conductor
III. Twist the strands of each conductor firmly in the direction of lay for 25mm leaving
50mm splayed out
IV. Untwist the splayed strands and straighten them
V. Interleave the strands and butt the twisted portions together. Each strand of the
conductor should lie should lie between two conductors of the other conductor
VI. Hold down the strands of the right hand conductor over the left hand conductor
neatly around the right hand conductor half a turn at a time keep the strands tight
and close together
VII. Wrap the strands of the right hand conductor round the left hand conductor as in
step VI
VIII. Cut off surplus strands on the bevel with side cutters smooth over with pliers
IX. Solder the joint. Wipe off any excess solder with a fluxed cloth pad
X. Make good the insulation removed

22. STRAIGHT MARRIED JOINT
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 Method seven stranded conductors
I. Remove insulation for about 75mm from each conductor
II. If VRI strip of and tape a further 12mm on each conductor
III. Twist the strands of each conductor firmly in the direction of lay for 25mm leaving
50mm splayed out
IV. Untwist the splayed strands and straighten them
V. Cut off the center strand from each conductor
VI. Inter leave the strands and butt the twisted portions together. Each strand of one
conductor should lie between two strands of the other conductor
VII. Lightly bind the strands on the right hand side round the twisted strands
VIII. Tightly bind the strands on the left hand side round twisted strands against the lay
of the conductor
IX. Untwist and straighten the strands on the right-hand side. Bind tightly round the
twisted strands
X. Cut off surplus strands on the bevel with side cutters smooth over with pliers
XI. Solder the joint. Wipe off any excess solder with a fluxed cloth pad
XII. Make good the insulation removed

23. STRAIGHT MARRIED JOINT
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24. TYPES OF JOINTS
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 Tee married joint Method (three stranded conductor)
I. Remove the insulation from the through piece for a distance of about
50mm in the center this wire must first be cut
II. If VRI cable strip off the braiding 12mm at each side
III. Remove the insulation of the tee piece a distance of about 75mm from
the end
IV. If VRI strip off the braiding and tape a further 12mm
V. Twist the strands of the through piece
VI. Twist the tee piece in the direction of lay for about 25mm from the
insulation
VII. Untwist the remainder of the length of the piece and straighten
strands
VIII.Offer the tee piece to the through conductor so that so the strands
are made to go round the left hand side of the through piece and the
strand round the right hand side of through piece
IX. Tighten the stands in their respective direction
X. Cut off surplus strands on the bevel with side cutters smooth over
with pliers
XI. Solder the joint. Wipe off any excess solder with a fluxed cloth pad
XII. Make good the insulation removed

25. TYPES OF JOINTS
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 Method (seven stranded conductor)
I. Remove the insulation from the through piece for a distance of about 50mm in
the center this wire must first be cut
II. If VRI cable strip off the braiding 12mm at each side
III. Remove the insulation of the tee piece a distance of about 75mm from the end
IV. If VRI strip off the braiding and tape a further 12mm
V. Twist the strands of the through piece
VI. Twist the tee piece in the direction of lay for about 25mm from the insulation
VII. Untwist the remainder of the length of the piece and straighten strands divide
into 4 & 3
VIII.Offer tee piece to through conductor so that four strands are on one side and
three on the other side of the through conductor
IX. Tighten the stands in their respective direction
X. Cut off surplus strands on the bevel with side cutters smooth over with pliers
XI. Solder the joint. Wipe off any excess solder with a fluxed cloth pad
XII. Make good the insulation removed

26. TYPES OF JOINTS
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27. TYPES OF JOINTS
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 Rat tail joint / Pig Tail.
 This kind of joint is commonly used to join two or more conductors
inside the junction box. It is suitable for service where there is no
mechanical stress when wires are to be connected in an outlet box,
switch, or conduit fitting
 Method
I. Strip the wire insulator at the ends of the conductor to be joined at
about 50 mm.
II. Clean both wires to be joined place the two ends of bare wire in
crossed position
III. Then, twist the bare conductors about five to seven times.

28. CABLE SOLDERING METHODS
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 solder
 There are two types of solder used in electrical work
Fine solder(tin mans solder)
Plumbers metal
I. Tin mans solder
 It has 60% tin and 40% lead
 Has a low melting point due to high amount of tin
 Commonly used in electrical joints
I. Plumbers metal
 It has 30% tin and 70% lead
 Is used for plumbing joints in armored cables as it remains
in a plastic shape allowing it to be shaped longer than fine
solder

29. SOLDERING BIT
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 Soldering Bit
 In this method the
conductors to be joined are
first smeared with resinous
flux. The tinned bit is then
applied under the joint until
the heat penetrates it The
stick of solder is then
applied to the joint until
solder flows through it
freely

30. BLOW LAMP
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 Stick Method(blow Lamp)
 In this method the joint is
first heated with a blow
lamp, flux being applied.
The solder is then applied
by pressing the stick of
solder against the heated
joint until it penetrates the
joint . Care should be taken
to protect insulation against
blow lamp flame

31. POT AND LADLE
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 Pot And Ladle
 This method is commonly used by
jointers when jointing heavy
conductors. A solder pot is
heated until the solder is running
freely. The solder should not be
overheated as this will burn the
tin and form a dross on the
surface of the solder. When the
solder has reached working
temperature it is taken from the
pot with a ladle. The solder is
then poured over the prepared
joint and is caught with another
ladle placed under the joint. This
action is repeated until the solder
penetrates the joint

32. THANK YOU
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