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ELECTRICAL CABLES AND

JOINTING Pratley-Glands and junction boxes

(LVJ)

Learner Guide

TABLE OF CONTENTS CABLE JOINTS (LOW VOLTAGE) PAGE 1

RESIN CAST JOINTS (LVJ-l )

RESOURCE NOTES PAGE 3

REVIEW BREAK NO. 1 PAGE 5

HEAT SHRINK JOINTS (LVJ-2)

RESOURCE NOTES PAGE 6

REVIEW BREAK NO. 2 PAGE 8 CABLE GLANDS (LVJ-3) AIMS & OBJECTIVES PAGE 9 LEARNING PROCEDURES PAGE 10 PART 1 : OVERVIEW OF CABLE GLANDS PAGE 11 REVIEW BREAK NO. 1 PAGE 14 PART 2 : COMPRESSION GLANDS PAGE 16 REVIEW BREAK NO. 2 PAGE 19 PART 3 : ARMOUR GRIPPING GLANDS PAGE 20 REVIEW BREAK NO. 3 PAGE 23 PART 4 : ADJUSTABLE GLANDS PAGE 24 REVIEW BREAK NO. 4 PAGE 26 PART 5 : EARTHING PAGE 27 REVIEW BREAK NO. 5 PAGE 28 PART 6 : USEFUL GLAND ACCESSORIES PAGE 29 ADDITIONAL NOTES PAGE 32 REVIEW BREAK NO. 6 PAGE 38 JUNCTION BOXES (LVJ-4) PART 1 : OVERVIEW OF JUNCTION BOXES PAGE 39 REVIEW BREAK NO. 1 PAGE 43 PART 2 : OVERVIEW CONVERSION KITS PAGE 44 REVIEW BREAK NO. 2 PAGE 45 PART 3 : BOX APPLICATIONS PAGE 46 REVIEW BREAK NO. 3 PAGE 49

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Back to Table of Contents 1

CABLE JOINTS (LOW VOLTAGE) INTRODUCTION Typical methods and procedures employed to create safe S.W.A. cable joints on low voltage cables are described and demonstrated in the following programmes: LVJ-1 Resin Cast. LVJ-2 Heat Shrink. This workbook (study guide) provides the basic instructional detail for performing the various joint types. PROCEDURE o Select the joint type that you wish to study before turning to the relevant page. o Select the video programme that accompanies the selected programme. o Follow the study guide suggestions as you learn about the selected joint by viewing the video. o Practice the creation of joints, as demonstrated, in your own training area under the supervision of your Instructor or Course Controller.


RESIN CAST JOINTS (LVJ-1 ) LEARNING PROCEDURES o Obtain Tech AV programme No. LVJ-1. o Read the resource notes beginning over page. o Perform any suggested practical exercises in your training centre or designated work area. SAFETY o On no account may you work on live or potentially live apparatus, supply or feed lines. You must ensure that your Instructor, Supervisor or Plant Safety Officer is aware of any work intended to be carried out on potentially live apparatus. A responsible person must verify that it has been isolated and where applicable de- energised, in accordance with standard factory and building regulations applicable in your area I plant. o During your initial practical exercises we strongly recommend that you practice creating joints using "off-cut" cable lengths.


RESOURCE NOTES (LVJ-1) RESIN CAST JOINTS INTRODUCTION

o Resin cast joints are popularly used owing to their relative ease of creation and efficiency especially with under surface installation or in areas where the use of heating apparatus (e.g. gas torch) may be an inhibiting factor.

o Joint Kits are available from most electrical accessory suppliers and the type demonstrated in the video is typical of most.

o Both armoured and unarmoured low voltage cables may be jointed using Resin Cast methods.

GENERAL INFORMATION Although the video demonstrates a typical procedure for creating or effecting a joint it should be well noted that the dimensions and some procedures may vary with other kit manufacturers. It follows therefore that you should read and implement the procedures outlined in the INSTRUCTIONS supplied by the kit manufacturer. GENERAL PROCEDURES The following steps are "usual" in creating a resin cast joint:

1. Isolation and de-energisation of existing line. 2. Selection of appropriate kit. 3. Preparation of cable ends. 4. Mechanical connection of conductors. 5. Preparation and installation of mould. 6. Preparation and application of resin filler compound.

1. ISOLATION

As per your standard safety procedures. 2. SELECTION OF KIT

A jointing kit is selected according to the outside diameter of the cable. o Measure the outside diameter of the cable and select the appropriate Kit number. o Check that contents of the kit are complete, including the instructions pamphlet.

3. PREPARATION OF CABLE ENDS

o Ensure cable ends are cleanly cut off and not damaged. o Ensure ends are dry (no water moisture present). o Abut! both cable ends and mark-off mould area. o Strip off the prescribed dimensions of sheath, armouring, bedding layer and


conductor tails on both ends.

(NB: On ECC cable -do not remove copper conductors in armouring.) 4. MECHANICAL CONNECTION OF CONDUCTORS

o Connect conductors using appropriate devises (e.g. crimped ferrules). o Ensure colour (phasing) coding is maintained.

NOTE: We recommend that ferrules are not bunched together, rather staggered.

On ECC types, twist conductors, trim to length and then join with an appropriate ferrule.

5. PREPARING THE MOULD (INCLUDING INSTALLATION)

NB: Most moulds have "stepped" diameters at either end which must be "trimmed off" to match the cable diameter.

o Measure the cable 0.0. with a vernier calliper. o Clip two halves of the mould together. o Check (compare) this 0.0. to the "step" which most closely approximates this

dimension. o Cut off the "surplus" core section at each end of the mould. o Roughen the cable sheath at the area where the mould will contact (i.e. abrade

area using emery tape). o Apply one or two layers of stretched rubber tape at the mould contact area (inner

seal). o Clip the mould into position over the joint and onto the tape. o Apply highly stretched rubber tape at ends of mould (outer seal). o Remove the pouring lid/cover. o Mix contents of "twin-pack" resin as per label instructions. o Pour resin into mould ... tapping the mould during this process will assist in removal

of trapped air bubbles. o When full -refit the moulds pouring lid/cover. o Allow approximately 30 to 40 minutes for the resin to set before moving the joint or

before energising the line.


REVIEW BREAK NO. 1 Having now read the resource notes, view the video (LVJ-1) after which you should attempt the exercise below. EXERCISE Using cable off-cuts perform a joint using a resin-cast jointing kit. NOTE: Follow the manufacturer's instructions which may, depending upon the kit manufacturer, differ slightly in detail or dimensions from that demonstrated in the video. Have your Course Controller I Instructor check you work at the following stages: 1. Upon completion of cable end preparation. 2. Upon completion of connecting phase conductors. 3. Upon assembly of mould over the joint (i.e. before you fill it with resin). 4. Upon completion of the joint.



RESOURCE NOTES (LVJ-2) HEAT SHRINK JOINT INTRODUCTION Modern heat shrinking materials, i.e. compounds that shrink when heat is applied to them, are commonly used to create an isolative layer around conductive cores. Together with S.F.T.S. tape (mastic) heat shrinking "tubes or sleeves" create a very efficient insulation and moisture seal. A typical heat shrinking "kit" is supplied with the necessary shrink tubes. S.F.T.S. tape and an earthing conductor, usually in the form of a woven strand copper-sock. Filler putty (butyl) is also provided to create a bedding and moisture protective layer between conductor cores. GENERAL PROCEDURE

o When creating a cable joint using a heat shrink kit you will require a butane torch (Handygas) which of course requires that you are familiar with the safety procedures relevant to gas apparatus.

o Cables are stripped back and prepared in similar fashion to that described in the previous programmes (Resin joint).

o The procedures for assembling and shrinking the insulation are adequately described in the notes and well demonstrated in the video programme (LVJ-2).

SPECIAL NOTE When applying heat use only a soft (blue/yellow) flame and keep the flame moving over the shrink material in order to avoid "scorching". PROCEDURES FOR KIT INSTALLATION The following steps are required for performing a heat shrink joint on a P.V.C. insulated cable. 1. SELECT THE CORRECT KIT Kits are usually selected according to cable size (i.e. core cross sectional area) and number of cores. Check the kit assembly instruction or box label for compatibility with your particular cable. 2. PREPARATION OF CABLE ENDS

o Whenever practically possible support the two cable ends on trestles (as demonstrated in video).

o NB: Slide both the short inner-tube and the copper earthing-sock onto the cables prior to connecting.

o Strip back the sheath, armouring and bedding according to specification in kit assembly instruction.


3. CONNECT PHASE CONDUCTORS o Slide steel support bushes beneath armours. o Slide ferrule sleeves over conductor cores. o Connect cores, and crimp the ferrules. o Apply S.F.T.S. tape onto either side of ferrules; overlap ± 10mm onto core insulation.

4. CREATE PRIMARY INSULATION AND CORE BEDDING

o Slide ferrule sleeves over ferrules and "centre" each upon the S.F.T.S. tape. o Shrink the ferrule sleeves, using a "soft" blue I yellow flame. o Fill gaps between conductor cores with "filler-putty". o Apply a layer of S.F.T.S. tape, to act as a seal, over inner bedding.

5. INSTAL INNER COVERING LAYER o Slide the inner tube (or sleeve) over the joint to overlap the tape seals (centre the

sleeve). o Shrink the sleeve, starting at the centre, working around the sleeve and outward to

either end. (Again use soft flame). 6. ATTACH THE EARTHING COPPER SOCK

o Slide sock over the joint and strap each end firmly onto the cables armour wires. NB: If straps not included in kit use proprietary stainless steel strapping).

o Trim off surplus copper strands beyond the straps. o Abrade (roughen with emery tape) cable outer sheath. o Wrap a layer of S.F.T.S. tape at each end, on abraded area, to form moisture seals.

7. FIT OUTER SLEEVE OR TUBE

o Slide outer sleeve over the joint and "centre" it over the 2 moisture seals. o Shrink the sleeve beginning at the centre and working outward toward either end. o The joint is complete and can be energised when required.


REVIEW BREAK NO.2 Having now read the resource notes, watch video (LVJ-2) to see the practical demonstration. Perform the suggested practical exercise. EXERCISE Using off-cut cables -perform a "heat shrink" jointing operation and have your Course Controller inspect at each stage of assembly:

1. After preparation of cable ends. 2. After crimping conductor ferrules and fitting support bushes. 3. After shrinking ferrule sleeves and fitting gaps with filler putty. 4. After shrinking inner sleeve and placing moisture seals. 5. After fitting the earth sock. 6. After shrinking the outer sleeve.



AIMS AND OBJECTIVES

The main purpose of the two programmes, glands and junction boxes, is to provide trainee electricians, millwrights or other relevant personnel, with the basics of the procedures and skills required in maintaining and fitting such devices. It must be noted that all procedures and tasks illustrated are typical, but not necessarily preferred by every regulatory authority or organisation. However, we stress that every effort has been made in the research of this subject to ensure that all facts and data conform to recognised international standards. When you have successfully completed this series you will be able to:

o Prepare cable end for the fitment of compression type glands or armour gripping glands. o Install or assemble typical glands. o Describe various safety features. o Make terminations in junction boxes.

The main aims of LVJ-3 and LVJ-4 is to provide trainees with the basic and essential information, by way of explanation and demonstration, in the selection and fitment of commonly available low voltage cable accessories namely, cable glands and junction boxes. Both programmes have been produced with the assistance of Pratley Manufacturing & Engineering Co. (Pty) Ltd which is Southern Africa's leading manufacturer of cable accessories. All procedures demonstrated refer to Pratley products which may not be identical to other brands, although the basic principles will be typical. When you have successfully completed these programmes you will be able to:

1. Identify and select appropriate components for cable-ends. 2. Prepare cable-ends and install compression and armour gripping glands. 3. Describe the requirements of "hazardous locations" in respect of glands and junctions. 4. Practice safe maintenance procedures.


LEARNING PROCEDURES It is strongly recommended that you begin with programme No. LVJ-3 (Glands) as many principles covered in this programme relate to programme No. LVJ-4 (Junction boxes) and are therefore assumed. GENERAL PROCEDURES

1. Read the resource notes before viewing the video. 2. Perform the suggested practical exercises after viewing the video. 3. Always inform your Course Controller when you are intending to perform a practical

exercise. SPECIFIC PROCEDURE

1. Read through these notes first, then when prompted in the "Review" section watch the relevant video section. You may view the video as many times as you deem necessary.

2. Stop the video when a "Review" break is seen on screen and perform the suggested exercise.

3. Continue with reading the next section and then viewing the video as in steps 1 & 2 above. 4. At the end of each programme your Course Controller may instruct you to perform a full

exercise on a suitable work-piece in your training environment. SAFETY All local and national regulations regarding safety permits, isolation and responsibility must be fully adhered to at all times.


PART 1 : OVERVIEW OF CABLE GLANDS

o The main purpose of a cable gland is to provide a safe mechanical means of securing, or anchoring, a cable at the point of entry into electrical apparatus.

o A secondary but very important function is that many glands are designed to provide a seal against accidental ignition in hazardous areas.

o Cable glands are categorised into two main groups, namely: 1. Compression glands -used on non-armoured cables. 2. Armour gripping glands -used on armoured cables.

A. COMPRESSION GLANDS

A rubber (or synthetic rubber) "bush" is used to create a "gripping" effect upon the cable sheath or bedding. The bush also acts as a seal to exclude water and dust.

Compression glands are available in plated brass or in "Tufflon" (plastic) materials.

Brass Glands for Unarmoured Cables Heavy

Duty range of Brass Glands for cables up to

44,0 mm OD

Also conversion kits up to 73,7 mm

Tufnol Compression Glands

Light Duty range of Glands for cables up

to 19,2 mm OD


GLAND COMPONENTS AND STANDARD SIZES

Compression Gland Dimensions

GLAND SIZE 0 1 2 3 4 5

Catalogue No's

Brass

Compression Gland

12068

12069

12070

12071

12072

12074

Type 'e'

Compression Gland

22090

22091

22092

22093

22094

22096

Dimensions Body 20.8 24.5 32 40.0 52 63

Compression Nut 19 22 30 37.5 50 60

Locknut 24 27 36 41 55 65

D Nipple Thread 20 20 25 32 40 50

E Nipple Bore 11.1 14.7 19.9 27.3 35.5 44

F Nipple Length 8 9.6 12.8 12.8 16 16

G Max Protrusion 28.3 30 34.5 39.1 48.2 56.4

F+G Overall Length 36.3 39.6 47.3 51.9 64.2 72.4

H Overall Diameter 28 31 42 49 64 76

Compression Gland Selection Table

Compressor

Gland

SIZE

No.

00 0 1 2 3 4

Cable Dia. Min 6.5 8.0 9.0 14.0 18.0 24.0

Range in mm. Max 9.2 11.1 14.7 19.9 27.3 35.0

Pratley Compression Glands use one

size of Compression Bush for each

gland size with one set of retaining

washers. The metal retaining washers

are only fitted when the cable diameter

is small enough to fit through them.

Where the cable diameter is too large,

only the supplied plastic skid washer is

used, placed between the Compression

Bush and the Compression Nut. This

simple method provides a way of

making one gland size accommodate a

wide range of cable diameters.

By the nature of their operation, Pratley

Compression Glands automatically seal

the bore of the gland against ingress of

moisture. Shrouds are not necessary.


B. ARMOUR GRIPPING GLANDS As the name suggests this type of gland is designed to grip and secure the cable via the steel wire armours.

The principle is that a tapered "cone-bush" is pressed between the armours and the bedding. The cone traps the armour wires against the gland body as it is compressed by tightening the cone-nut.

Adjustable and non-adjustable types are available.

Schematic showing typical construction of an armour gripping gland (Pratley designed adjustable type).


REVIEW BREAK NO. 1 Having now read the resource notes, view the first part of the video programme LVJ3 up to the first Review Break. SUGGESTED EXERCISE o In your training area take a look at the various cable glands. o Study manufacturers catalogues that are available and get familiar with gland types, designs and terminology.




PART 2 : COMPRESSION GLANDS

FITTING PROCEDURES (NON-ARMOURED CABLES) Our first consideration is to establish which size gland we require to suit the cable. The Pratley SIZE

selection chart is used to do this.

READING THE CHART (FOR UN ARMOURED CABLES)

(NOTE: Please refer to Pratley size selection chart).

STEP 1

o Measure the diameter of cable (across outer sheath).

o Refer to section "D" for un-armoured cables.

o Look at the table for Brass Compression Glands.

o Look at the "Diameter" column (Min I Max.) for round cable (as we are working with round

type cable in this example).

o Find the diameter of your cable e.g. if your cable is say 1 0,2 mm then use the row indicated

as 9.0 min -14.7 max.

o Trace across to the "gland size" column. Obtain gland size (in our example we require a No.

1 gland).

STEP 2 o Assess where on the cable you need to place the gland by: 1. Measuring the required "tail" length in the apparatus (e.g. distribution board). 2. Mark off the gland position with tape on the cable. STEP 3 o Assemble the gland onto the cable according to the manufacturers fitting instructions (see

Brass Compression Glands

Round Cable Flat twin & Earth Cable

Diameter mm Min Diameter mm Max Cable Size Gland Size Nipple thread

6.5 9.2 - No 00 16mm

8.0 11 .1 Ripcord & 5A x2 core No 0 20mm

9.0 14.7 1.5mm² 2.5mm² 4.0mm² No 1 20mm

14.0 19.9 6.0mm² 10.0mm² No 2 25mm

18.0 27.3 16.0mm² No 3 32mm

24.0 35 .0 - N0 4 40mm

32.0 44.0 - No 5 50mm


sample below -courtesy Pratley Manufacturing & Engineering (Pty) Ltd). Table "A" Box / Gland Size

Dimens mm 0 1 2 3 4

A 235 242 280 314 339

B 22.0 27.0 35.0 38.0 43.0

C 13.0 15.0 15.0 16.0 16.0

D 200 200 230 260 280

FITTING TUFFLON GLANDS In principle the procedures for a Tufflon gland installation is virtually identical to the brass type. Note that only one retainer washer is required ... namely the plastic "skid" washer. This must be fitted between the compression nut and compression bush. ADAPTER BUSHES To "convert" a gland in order to accommodate "flat-twin and earth" type cable we need only replace the conventional compression bush with an "oval adapter bush". Refer to the Pratley size selection chart, section D, under the Tufflon Compression gland section to select the required gland size to suit the cable size or use chart below.

Turn rubber Water-proofing shroud inside

out, pull over cable, large end first.

Prepare cable end, exposing armouring, bedding

and conductor "tails" as per lengths in table "A".

Stretch rubber sealing bush over bedding &

push into position against face of cone bush.

Once assembled, all components

will be in this position. CABLE READY

TO BE FITTED

TO CABLE BOX


Notes: ▪ When fitting, use plastic skid

washer. □ When fitting, use both metal retaining washers.

* These glands are supplied complete with correct adapter bush & washers. ± When fitting use plastic skid washer only.

Cable Size Gland Type & Size

Gland Cat No.

Notes Use Oval Size

Adapter Bush Cat No.

Ripcord 2

core 5A

No. 00 Tufflon

No. 0s Tufflon

75101

75101

▪

▪

5

5

12100

12100

1.5 mm²

No. 0L Tufflon

No. 1 Tufflon

No. 1 Brass

75105

75106

12069

*

*

□

*

*

6

*

*

12101

2.5 mm²

No. 1 Tufflon

No. 1 Brass

75106

12069

*

□

*

6

*

1210

4 mm²

No. 2 Tufflon

No. 2 Brass

75109

12069

*

±

*

6

*

12101

6 mm²

No. 2 Tufflon

No. 2 Brass

75109

12070

*

□

*

7

*

12102

10 mm²

No. 2 Tufflon

No. 2 Brass

75109

12070

*

±

*

8

*

12102

16 mm² No. 3 Brass 12071 □ 8 12103


REVIEW BREAK NO.2 Having now read the resource notes continue viewing the video and perform the suggested exercise. EXERCISE Practice the fitting of compression type glands on suitable cable off-cuts in your work area.



PART 3 : ARMOUR GRIPPING GLANDS NON-ADJUSTABLE FITTING PROCEDURES (ZED GLAND)

o Again our selection of a suitable gland size is made using the Pratley Size Selection Chart. This time we would refer to Chart A.

o If you happen to know the cable size (i.e. the cross sectional core diameter) then refer to the column headed "cable size".

o Alternatively measure the bedding diameter of your selected cable and use the column headed "Max. Bedding Dia. mm".

o Select appropriate gland size from column headed "Gland or Box Size". CABLE PREPARATION

o Positioning of Gland on cable is assessed by measuring required tail lengths at the apparatus.

o Allow a little surplus for final trimming purposes. o Mark cable with a wrap of insulation tape at the measured position.

NOTE: Add the length of the assembled gland to your measurement off the apparatus. o Slide rubber shroud onto cable before stripping.


Fig 5. Typical Distribution Board application.

Gland Size 0 1 2 3 4 5 6 7 8

Dimension A

(min)

11

mm

13

mm

16

mm

20

mm

20

mm

23

mm

25

mm

29

mm

29

mm

Fig 6. Stripping dimensions for armoured cables.

o Strip back cable end to the specifications provided on gland instruction pamphlet. (Typical example shown -courtesy of Pratley Manufacturing & Engineering (Pty) Ltd).

ASSEMBLING

o Slide compression nut onto armour section. o "Splay" the armouring to open it for access of cone-bush.

Furthermost

terminal point

Measure

the required

tail length

Allow excess

Allow

gland

length Gland entry

position


o Slip cone-bush between armouring and bedding. NOTE: Make sure that no wires end up inside the cone-bush bore.

o Fit gland body over armour and mate with compression nut threads. o Secure compression nut firmly into gland body. o Check, by pulling, that the gland is locked onto the cable. o Install the whole assembly into apparatus and firmly tighten the lock-nut. o Slide shroud over gland body and engage the lip into the annular recess around the gland

body.


REVIEW BREAK NO.3 Having now read the resource notes continue viewing the video, then perform the suggested exercise below. SUGGESTED EXERCISE Obtain off-cuts of S.W.A cables and practice the fitting of armour gripping glands of the non-adjustable type.



PART 4: ADJUSTABLE GLANDS PURPOSE Adjustable glands are designed in such a way that they can be used over a range of diverse cable sizes, with "non-standard" cables, with varying S.W.A. thicknesses or with poorly prepared armour. These glands are simple to install and the "adjustable" feature ensures a positive grip onto a cable even when only "hand" tightened. BASIC CONSTRUCTION

FITTING PROCEDURE o Select gland size according to bedding diameter from Pratley Chart Section A. o Fit rubber shroud onto cable (inverted). o Cut (strip) back the cable end in accordance with the fitting instruction pamphlet for

bedding diameter. o Ensure that the required armour length is exposed. o Fit the cone-nut onto armours.

(A) The HEAVY PATTERN PLATED STEEL LOCKNUT and (B) HIGH TENSILE BRASS NIPPLE permits very

generous tightening of the cable gland to the apparatus without fear of the Gland snapping off.

(C) The SPIGOT on the face of the DIFFERENTIAL NUT enables each Gland size to centre in two different sizes of knockout hole ensuring a quality fit, neatness and good earthing. (D) The threads of different pitch in the DIFFERENTIAL NUT provide a self-locking action that locks all parts of the Gland in the! adjusted position. (E) The CONE BUSH is self-centring which ensures an even grip on each wire of the armouring. It is also made of high tensile brass, permitting generous tightening without fear of distortion. (F) The "long" skirted Pratley Waterproofing Shroud seals on the cable sheath, the gland differential nut and against the apparatus, for absolute protection.

This total exclusion of moisture and corrosive atmospheres, together with the gland's nonreturnable valve action ensures a safe and permanent earth. Made from a unique space age rubber, specially developed in our laboratory over many years, Pratley shrouds revolutionised the obsolete, expensive and ineffective outer seal designs prevalent in the sixties. "Short" (unskirted) shrouds are also available.


o Splay armours to accommodate cone-bush. o Slip the cone-bush between armours and bedding. o Assemble the nipple into the differential nut so that it catches approximately on 2 threads

(i.e. it is virtually screwed all the way out). o Mate the differential nut with the compression nut, then screw them together leaving

about 2 to 3 threads loose (i.e. before the gap closes between deferential nut and compression nut).

o Turn the adjusting nipple, by hand, into the differential nut until it is tight. o Tighten up the differential nut fully against the compression nut. o Assemble the gland into the apparatus -locking it up with the lock nut. o Fit the rubber shroud.


REVIEW BREAK NO.4 Having now read the resource notes, watch the video to the next review break, then perform the exercise. EXERCISE Practice the fitment of adjustable glands on various cable off-cuts in your work area. Have your Course Controller check your work.



PART 5: EARTHING 1. E.C.C. EARTHING ON ARMOUR GRIPPING GLANDS

o When preparing the cable end of E.C.C. type cable you should not remove the copper conductors in the armouring layer.

o Bend the copper earth conductors back prior to removing the galvanised steel wires. o On assembly of the gland position the E.C.C. conductors through the cone bush bore. o Position the cone-bush between the bedding and the steel wires. o Assemble the gland in the manner previously described. o Install the cable into the apparatus in the usual way. o Twist the E.C.C. strands into a "core" before termination at the earthing position.

2. EARTHING TAGS

o Where a separate earth return is required (on S.W.A. cable) at the gland then we must install earth tags.

o Earth tags are installed on the nipple end and secured with the normal locknut. NOTE: 1. Scrape or file off any paint, dirt etc. on apparatus to create a clean metal to metal

contact between the earth tag and the apparatus. 2. As a rule the cross sectional area or 'rated area' of the earth tag must be equal to (at

least) 1/2 cross sectional area of the phase conductor. For example, a 50mm2

cable

size must have 25mm2

tag.


REVIEW BREAK NO.5 Having now read the resource notes, continue watching the video up to the next review, then perform the exercise. EXERCISE In your training area, practice the installation of earthed connections, both E.C.C. and separate earth, using adjustable glands into a O.B. unit. Have your Course Controller check your work.



PART 6 USEFUL GLAND ACCESSORIES Cable glands, terminal housings and junction boxes are often situated in areas where they are exposed to rain, water spray, corrosive chemicals and many other potentially harmful or dangerous products. Glands and terminal devices, especially those found on plant equipment, should be protected from all harmful elements which could result in:

o Corrosion to metal components. o Short circuits at terminal blocks.

The minimum protective device is a rubber shroud usually supplied with all nickel plated brass glands. NOTE: Armour gripping glands should always be fitted with at least a rubber shroud some require more protection which we'll discuss shortly. INNER SEALING KITS An inner sealing kit is available for creating a watertight seal within an armour gripping gland of the adjustable only. The kit comprises of an inner sealing bush and a cone-ring. The components are installed, as demonstrated in the video, within the gland and upon tightening the differential nut an effective seal is created by the "compression" of the sealing bush against the cable bedding. NOTE: With "compression glands" on un armoured cable a watertight seal is automatically created.

Inner seals are used to seal pressure tight against the cable bedding.

COMPRESSION CONVERSION KIT As may occur on site you are faced with a situation that requires the fitting of an nonarmoured cable but you only have armoured glands available. By installing a compression conversion kit the gland is able to fit, and seal, the cable.

PRATLEY INNER SEALS KITS FOR CABLE GLANDS


The kit comprises a rubber "compression bush" and two metal retainers. The original cone and bush is discarded and the kit components fitted to replace the removed parts (demonstration on video).

THREAD ADAPTERS Many electrical junctions have threaded parts of entry which mean that the gland will have to be modified in order to screw in to the hole. This can be achieved, on adjustable glands, by replacing the adjustable nipple with an adapter. Adapters are available to suit all gland sizes and various international threads (e.g. DIN Standard and imperial). PRATLEY ADAPTERS

PRATLEY COMPRESSION CONVERSION KITS

For use with Pratley Adjustable Cable Glands.

Compression Conversion Kits replace the Cone

Bush in Glands so that they may be used with any

un armoured (circular) cable.

PG. ADAPTERS

Pg. Adapters replace the Standard Nipple in

the Pratley Adjustable Gland so that the

Gland may be screwed directly onto Pg.

threaded entries (DIN Standard).

IMPERIAL ADAPTERS

These Adapters replace the Standard Nipple

in the Pratley Adjustable Gland so that metric

Glands may be screwed directly into imperial

threaded holes.

EXTENDED LENGTH NIPPLES These nipples for Pratley adjustable Cable Glands replace the standard nipple when required for use with exceptionally thick gland plates. SHROUDS Two shroud length are available: Standard and Long.


SHORT SHROUD LONG SHROUD


ADDITIONAL NOTES NOT INCLUDED IN VIDEO HAZARDOUS LOCATIONS

Although this is the subject of a full training module we wish to include some important information regarding hazardous locations especially in respect of cable glands (and junction boxes). Certain industries are prone to the creation of conditions which could cause a fire or explosion should a spark occur, (e.g. from a "hot" electrical connection). Industries that create a "hazardous" condition have been classified into 3 general "classes". Listed below are the general classifications and the sub-divisions for purposes of general reference as supplied by the South African Bureau of Standards (S.A.B.S.).

THE CLASSIFICATION OF HAZARDOUS LOCATIONS A BRIEF SUMMARY (FOR DETAILS SEE S.A.B.S 0108)

FLAMMABLE GASES OR VAPOURS FLAMMABLE DUSTS FLAMMABLE FIBRES

CLASS 1 CLASS 11 CLASS 111

Division 0 - Division 1 - Division 1A - Division 2 -

Atmosphere continually explosive. Atmosphere likely to be explosive under normal operating conditions. Conditions same as in 1 but with added hazard of toxic or irritating gases. Atmosphere explosive only under abnormal conditions.

Division 1 - Division 2 -

Atmosphere likely to contain ignitable concentrations of flammable dusts in suspension under normal operating conditions. Atmosphere not likely to contain suspended dust but presence of ignitable dust may create a hazard.

Division 1 - Division 2 -

Atmosphere likely to be contaminated through manufacture or usage of fibrous materials. Atmosphere not likely to be contaminated as area is used only for storage of fibrous materials.

The point we want to stress is that one cannot fit any cable, to any gland or junction if the apparatus is situated in a classified "hazardous location". Electrical apparatus, which includes all accessories, connections, cables etc. used in hazardous locations must conform to stringent standards and be approved by regulating authorities (e.g. Chief Inspector of Machinery, Government Mining Engineer). Glands and Junction Boxes in hazardous locations must be "rated" according to the type of protection that they offer by way of their design, construction or features incorporated. For example, an EXE rated gland is designed to be safely used in Class I Division 2 locations (i.e. open air pipes and pumps which are pumping fuel but are some distance from Class I Division 1 areas).


This can become confusing, and as we said earlier is the subject of a full training module on hazardous locations. To assist you in the subject, for purposes of appreciating the importance of safety, we include 4 pages of reference material, which we suggest you study should you ever be required to work in a hazardous location. thereafter we strongly recommend that you familiarise yourself with Section 8 of the Machinery and Occupational Safety Act.

AN EXAMPLE OF EACH OF THE VARIOUS CLASSIFIED AREAS

CLASSIFICATION EXAMPLE

CLASS I DIVISION 0 - Space above certain fuels or solvents in storage tank.

CLASS I DIVISION 1 - Volatile paint spray booth.

CLASS I DIVISION 1A - Vent on a blast furnace gas pipe line. (the gas is poisonous even in concentrations below the explosive limit).

CLASS I DIVISION 2 - Open air pipes and pumps which are pumping fuel and which are some distance from the nearest CLASS I DIVISION 1 area.

CLASS II DIVISION 1 - Discharge bin in a grain silo.

CLASS II DIVISION 2 - Working areas in grain elevators.

CLASS III DIVISION 1 - Discharge pipe in a cotton gin.

CLASS III DIVISION 2 - Textile mill bulk store.

TERMINOLOGY: "EXPLOSION PROTECTED" The term "Explosion Protected" is a generic term for all electrical apparatus designed for use in hazardous area. It is not a term reserved specifically for Flameproof apparatus.


CHART OF S.A.B.S. 1222 (IP DESIGNATIONS)

FIRST

DIGIT

NUMERAL

DEGREE OF PROTECTION

(FOREIGH BODIES)

SECOND

DIGIT

NUMERAL

DEGREE OF PROTECTION

(LIQUIDS)

0 No protection of equipment

against ingress solid foreign

bodies.

0 No protection.

1 Protection against ingress of

large solid foreign bodies.

1 Protection against drops of

condensed water.


medium-size solid foreign

bodies greater in thickness than

1 mm.

2 Protection against drops of liquid

falling at any angle up to 15

degrees from the vertical.


small solid foreign bodies.

3 Protection against rain falling at

any angle up to 60 degrees from

the vertical.


small foreign bodies greater in

thickness than 1 mm.

4 Protection against splashing

liquid splashed from any direction

shall have no harmful effect.


dust in an amount sufficient to

interfere with satisfactory

operations of the equipment

used.

5 Protection against water

projected by a nozzle from any

direction.

6 Complete protection against

ingress of dust.

6 Protection against any conditions

on ships decks.

7 Protection against immersion in

water.

8 Protection against indefinite

immersion in water.

E.G.: IP68 = Dust Proof and Waterproof when immersed in water over long periods.


APPLICABILITY OF TYPES OF PROTECTION

PROTECTION AREA NOTES

EXi Class I Division 0 Category ia only, not Category b.

EXd Class I Division 1 Check gas type and enclosure group.

EXp Class I Division 1 Provided certain interlocks fitted.

EXq Class I Division 1 Provided enclosure is suitable.

EXm Class I Division 1

EXe Class I Division 2

some cases

Class I Division 1

Some apparatus e.g. Junction Boxes and

Cable Glands - Class 1 Division 1 (Check

gas and temp rating and enclosure impact

rating).

EXN Class I Division 2 Check gas and temp rating.

DIP/HP Class II Division 1

And Division 2

Exe RATED CABLE GLANDS Cable glands suitable for installation in Exe rated locations must bear this:

In essence Exe glands are sealed both internally and externally, typically as illustrated below.

IMPORTANT NOTE: IF DURING FITTING, YOU FORGET TO FIT ANY OF THE ITEMS LABELLED IN THE DIAGRAM, THEN THE GLAND IN NO LONGER EXE RATED ASSEMBLY!


EXd (FLAMEPROOF) CABLE GLANDS Featured here is the Pratley designed flameproof gland, illustrating its construction and explaining its design features. Note that, when assembling such a gland it is of absolute importance to follow the fitting instructions "to the letter" in order to ensure safety.


CORROSION "PROOF" GLANDS In areas where corrosion of metal (e.g. the S.W.A. strands in a cable) is likely to happen then the use of an "Enviro-gland" or an "Enviro-seal" would be recommended. An "Enviro-gland" is an integral gland containing all the metal internal components of a normal armour gripping type gland but is totally encapsulated with corrosion proof material. An "Enviro-seal" is an "add on" component which effectively replaces the normal shroud on adjustable type glands. Extremely "tight" sealing is effected between the cable sheath and "labyrinth seal" within the unit -to positively exclude water, dust or other contaminants.

Modern flameproof ( Exd ) cable glands achieve safety by sealing onto the cable bedding & thereby preventing the escape of hot gas or flame under explosive conditions. If the gland & cable bedding sizes are not properly matched, the bedding may be too small for the gland bushes to seal onto. This is a dangerous condition! Pratley now supplies a patented go/not go safety gauge integral with the gland packaging. Use of the gauge is pictorially explained so that even illiterate persons can understand its use & ensure perfect cable size matching & safety.


REVIEW BREAK NO.6 Having now read the resource notes, view the video LVJ-3, to the end. When you have completed the viewing we suggest you attempt the exercise below. SUGGESTED EXERCISE Ask your Course Controller I Instructor I Supervisor to point out where, if applicable, any hazardous areas exist in or around your place of work I plant area. Obtain samples of various glands which your company uses and study their construction. Study the manufacturers fitting instructions for the types of glands used. Practice the installation or assembly of various glands on sample cables within your training area. (NB: Not, of course, on live equipment!)

PROCEED TO LVJ-4 (JUNCTION BOXES)



PART 1 OVERVIEW OF JUNCTION BOXES Having dealt in some detail with glands in the previous section you should have no difficulty at all here in this module as many of the facts and procedures are almost identical. A junction box, or if you prefer, a "cable-box" is simply a means of safely housing a terminal connection when two or more cables are joined. When a single incoming supply is "split" the connection is generally made within a junction box. A variety of different types, shapes, sizes and construction details are available, serving many and varied requirements in both domestic and industrial applications. We shall be concentrating primarily on "Pratley" boxes of the type mainly encountered within industrial environments, although the same types are often encountered in domestic situations too. THE "EZEE-FIT" TYPE NB: "Ezee-fit" is a registered trade name and the design is patented by Pratley Manufacturing &Engineering (Pty) Ltd. The principle feature of an ezee-fit box is that it is made from non-metallic material and has an integral gland situated in each cable entry. The gland is of the armour gripping type, but can be easily converted to accommodate non-armoured cables or conduit adapters. The box is constructed from reinforced plastic. material (or resin) and is particularly suitable for underground installation. Earthing continuity is achieved by encapsulated copper rods that inter-connect between the glands. The box is sealed via an inner sealing bush within each gland and by a cover (or lid) gasket. The selection of an appropriate sized box is made in the same way as you selected an appropriate sized cable gland i.e. by referring to the Pratley Size Selection Chart as you learned in the previous programme.


Cable Glands

CABLE INSTALLATION INTO BOX

o All Ezee-fit boxes are supplied with. detailed fitting instructions. Cable preparation is made according to the detail supplied on the pamphlet for armoured cable.

o Gland components are removed from the gland entry part and assembled onto the cable as described.

o Assembly and securing of the cable and gland is made simply by threading the compression nut into the box opening. Typical fitting instructions are given over the page (courtesy of Pratley Manufacturing and Engineering (Pty) Ltd).

A. Synthetic rubber

'O' Section gasket.

B. Synthetic rubber inner seal brush.

C. Synthetic rubber waterproofing

shroud seals tightly in shroud

groove.

D. Encapsulated copper earth rods.

E. Compression ring facilitates grip

on armour wires & prevents

distortion of cable when gland is

tightened.

F. Cable cores connected with end

connector & insulating sleeves.


FITTING INSTRUCTIONS FOR EEZE-FIT CABLE BOXES

CABLE PREPARATION

FITTING CABLES INTO CABLE BOX


FITTING INSTRUCTIONS FOR EEZE-FIT CABLE BOXES


REVIEW BREAK NO. 1 Having now read through the resource notes, watch the video programme No. LVJ-4 up to the first Review Break. Pay particular attention to the demonstrations and then re-Iook at the manufacturers fitting instructions to see how the demonstrations followed the written instructions. Perform the suggested exercise. SUGGESTED EXERCISE

o Using off-cuts of armoured cable and a suitably sized Ezee-fit junction box, make off and fit at least two cables, into the box.

o Make the internal terminations using suitable end-connectors. o Have your Course Controller inspect your completed work.




PART TWO: CONVERSION KITS 1. FOR UN ARMOURED CABLES

Ezee-fit boxes will accept un armoured cables but you will first need to obtain a "compression conversion kit" of suitable size. Reference to Chart B on the instruction pamphlet is made to decide which kit size to purchase in relation to the cables "outside diameter, and the box size being used. (Go back to the instruction pamphlet and see section 3 for "Cable entry Adaptions").

Note that kits marked with an "s" (e.g. 3s) include an additional retainer washer, which is necessary to the smaller diameter cables in the kit-range. Removal of the existing inner bush seal, compression-ring and cone-bush, from the box gland is necessary if you fit a "compression-conversion kit".

2. FOR SMALL DIAMETER CABLES

It may be necessary that you need to run an armoured cable out of a junction box that is

smaller than the feed or supply cable . For example, your incoming cable of 4mm2

may require a No. 3 box owing to its bedding diameter, but your outgoing cable may be only a

2,5mm2. In such a situation you will have to fit a "reducing gland and shroud". Refer to the

fitting instruction section 4 -which illustrates and explains the fitment of a reducing gland. 3. CONDUIT ADAPTERS

In order to fit black metal conduit into a junction box you will require a "conduit adapter". Various sized adapters are available to suit both the conduit thread size / pitch and the box gland size I pitch. Refer to Section 5 of the fitting instruction pamphlet for sizing details.

4. UNUSED ENTRY POSTS

All junction boxes, when fully installed, must be sealed to prevent ingress of undesired elements (e.g. dust, water, etc.). In the event that you have, for example, a 4 way box ... but you only used 3 entries ... the 4th entry or gland must be sealed off. This is achieved by removing all the inner gland components as well as the compression nut and "blanking off' the entry with a suitably sized I pitch "blanking plug and sealing washer". Always fit the washer otherwise the box will not be sealed.


REVIEW BREAK NO.2 Having now read the resource notes, watch the video up to the 2nd Review Break. when you have finished viewing .. perform the exercise suggested below. SUGGESTED EXERCISE

o Using off-cut un armoured cabling practice the fitment of compression glands to a junction box.

o Make off a connection involving different cable diameters within one box. o Have your Course Controller check your work.


PART 3: BOX APPLICATIONS 1. SURFACE APPLICATIONS

Boxes designed for surface (i.e. above ground level) applications and in "nonhazardous" environments may be constructed in aluminium alloy. These are usually resin coated making them suitable for exterior mounting where they are exposed to weather, water spray etc. Alloy boxes are not considered suitable for use in "corrosive environments" nor for under-surface installation. Being "conductive" ... alloy boxes require no special earth conductors between the glands, however an "earth boss" is provided within the box to serve as a common earthing point.

Cable fitment, adapters and other accessories used on Ezee-fit boxes apply with the alloy boxes.

2. FLAME PROOF BOXES AND MAINTENANCE KITS

Specially constructed boxes, known as "flame proof' cable boxes are available and suitable for use in certain hazardous locations (e.g. fiery mines).Flame proof boxes are constructed using cast-iron. They do not have integral glands and must be used in conjunction with "flame proof glands". Each entry port is threaded to accept the nipple of suitably sized glands. Sealing of a flame proof box is critical; gland nipple sealing washers and lid gaskets must always be in perfect order and always fitted. You will notice that the lid (or cover) facings are broad and machined with grooves (much like the grooves on a record). These grooves play a key role in retarding the passage of flame and heat in the event that a flame (i.e. explosion) should ever occur within the box. Cable end connections within the box must always be made with non-sparking connectors equipped with lock-nuts to minimise any chance of a loose or "hot" connection.


BASIC DETAILS FOR TYPICAL FLAMEPROOF BOX


MAINTENANCE Junction boxes and glands, once properly fitted and assembled actually require no maintenance. However at any time that a box is uncovered, or a new cable is run from the junction, then the gaskets and cable seals may be unavoidably disturbed. When re-assembling glands, or when replacing lids always make sure that: a. The gasket is in position. b. Gaskets are not damaged. c. The lid is tightened securely and that it is fitting "flush" to the body (i.e. there are no gaps). When dealing with Exe flame proof units make special care to ensure that: a. Gland seals and nipple gaskets are installed and ... b. ... that they are not damaged in any way. c. Facings on lid cover and body are not in any way damaged, badly scratched or covered in dirt which may cause any interference with sealing effect. d. Lid screws are firmly tightened. e. Shrouds are in perfect condition and properly attached. GENERAL TIP Whenever in doubt ... always follow the manufacturer's instructions or contact their consultants for professional advice.


REVIEW BREAK NO.3 Having now completed reading the resource notes, finish by viewing the video to its conclusion, then do the suggested exercise to complete this section. SUGGESTED EXERCISE

o Under the supervision of a competent person practice the installation of cable boxes on circuits in your place of work.

o Pay special attention to neatness and to detail according to specifications. SAFETY

o It is imperative that all work is carried out within the specifications and regulations set out in your countries ruling ordinances (E.g. The Occupational Safety and Health Act, Machinery and Occupational Safety Act, Mines and Works Act etc.).

o You should already be familiar with any Safety Acts; however, should you not be then read them and get to know them well ... before you attempt any work on potentially live circuits.


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