• Large range of compatible fittings. • All boxes have brass inserts. • Withstands the most hazardous site conditions. • Non-flame propagating. • Lightweight. • Exceeds stringent British and European Standard requirements. For LSOH Conduit see MT Supertube on pages 136-139. Conduit and fittings are manufactured from Super High Impact PVC-U. PVC-U CONDUIT SYSTEMS Section Contents Pages Round Conduit 119 Round Conduit Fittings 120-124 Round Conduit Accessories 125 Round Conduit Accessory Boxes 126-127 Oval Conduit 128 Flexible Conduit 129 Corrugated Conduit 129 Cable Covers 129 118
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• Large range of compatiblefittings.
• All boxes have brassinserts.
• Withstands the mosthazardous site conditions.
• Non-flame propagating.
• Lightweight.
• Exceeds stringent Britishand European Standardrequirements.
For LSOH Conduit see
MT Supertube on pages 136-139.
Conduit and fittings are manufactured from
Super High Impact PVC-U.
PVC-U CONDUIT SYSTEMS
Section Contents PagesRound Conduit 119
Round Conduit Fittings 120-124
Round ConduitAccessories 125
Round Conduit Accessory Boxes 126-127
Oval Conduit 128
Flexible Conduit 129
Corrugated Conduit 129
Cable Covers 129
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ROUND CONDUIT
Light Gauge – White or blackProd Code O.D. PackCR2WH 20mm 30 x 3mCR3WH 25mm 30 x 3mCR4WH 32mm 10 x 3mCR9WH 38mm 10 x 3mCR10WH 50mm 10 x 3mFor black replace the last two lettersof the code with BK.
Heavy Gauge – White or blackProd Code O.D. PackCR6WH 20mm 30 x 3mCR7WH 25mm 30 x 3mCR8WH 32mm 10 x 3mCR11WH 38mm 10 x 3mCR12WH 50mm 10 x 3mFor black replace the last two lettersof the code with BK.
Twin Through Way or HProd Code Size Pack2MRB15WH 20mm 203MRB15WH 25mm 10
ROUND CONDUIT FITTINGS continued
PLAIN BOREDCIRCULAR BOXES
Available in white or black. Fixingcentres 50.8mm fitted with M4 brassinserts. Provision for brass earthingterminals. Boxes meet requirementsof BS EN 50086 and BS4607 whereapplicable and the requirements ofthe BS7671 Wiring Regulations. Theyare suitable for suspending a loadof up to 3kg centrally at 60ºCmaximum.
Twin Through Way or HProd Code Size Pack2MRB15WH 20mm 203MRB15WH 25mm 10
ROUND CONDUIT FITTINGS continued
PLAIN BOREDCIRCULAR BOXES
Available in white or black. Fixingcentres 50.8mm fitted with M4 brassinserts. Provision for brass earthingterminals. Boxes meet requirementsof BS EN 50086 and BS4607 whereapplicable and the requirements ofthe BS7671 Wiring Regulations. Theyare suitable for suspending a loadof up to 3kg centrally at 60ºCmaximum.
Nylon Draw TapeProd Code PackMDT10 1 x 10mMDT20 1 x 20mMDT30 1 x 30m
Cheese Head ScrewsProd Code PackM4 x 8mm 200M4 x 12mm 200M4 x 20mm 100M4 x 25mm 100
Lubricant SealantProd Code PackMSC1 1 x 100gm
*Conduit Solvent CementProd Code PackMSC20 1 x 250ml*Child resistant lid
*Trunking Solvent AdhesiveProd Code PackMSC3 1 x 250ml*Child resistant lid
ROUND CONDUIT ACCESSORIES
CONDUITACCESSORIES
IN ACCORDANCE WITH COSHH REGULATIONS DETAILS OF OURSOLVENTS ARE ENTERED IN THE NATIONAL POISON CENTRE
COMPUTER RECORDS. HEALTH AND SAFETY DATA SHEETS AREALSO AVAILABLE ON THE MARSHALL-TUFFLEX WEB SITE,
www.marshall-tufflex.com
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Single Gang – SquareProd Code Depth PackMSSB10KWH 32mm 20
Twin Gang – SquareProd Code Depth PackMSSB11KWH 32mm 10
Single Gang – SquareProd Code Depth PackMSSB17KWH 44mm 10
Single Gang – RadiusProd Code Depth PackMSSB40KWH 44mm 10
Twin Gang – RadiusProd Code Depth PackMSSB21KWH 32mm 10
Single Gang – RadiusProd Code Depth PackMSSB4WH 35mm 20
Twin Gang – RadiusProd Code Depth PackMSSB48KWH 28mm 10
ROUND CONDUIT ACCESSORY BOXES
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Twin Gang – RadiusProd Code Depth PackMSSB41KWH 44mm 5
All boxes have brass inserts andprovision for earth terminal which isseparately available.
Dimensions Fixing CentreSingle Gang 87 x 87mm 60.3mm TwinGang 147 x 87mm 120.6mmTo the requirements of BS 4662.
Standard colour – white.Coloured boxes, including red for FireAlarm Installations, are available toorder in production quantities.Boxes with suffix ‘K’ have ø20mm K.O. in centre top for surfaceentry. MSSB10KWH and MSSB11KWHhave a moulded ø 20mm hole.Alternative K.O. configurations areavailable to order.
SURFACE MOUNTED ACCESSORY BOXES – RADIUS CORNERS
SURFACE MOUNTEDACCESSORY BOXES –SQUARE CORNERS
FOR PLAINACCESSORY BOXES
SEE PAGES 131 TO 132
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Twin Gang – SquareProd Code Depth PackMSSB23KWH 44mm 5
Single Gang – RadiusProd Code Depth PackMSSB19KWH 32mm 20
Single Gang – RadiusProd Code Depth PackMSSB46KWH 28mm 20
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Single Gang – Adjustable LugProd Code Depth PackMSSB47WH 47mm 10Entries: 2 x ø20mm on each of 4sides.
Twin Gang – Adjustable LugProd Code Depth PackMSSB3WH 35mm 6Entries: 4 x ø20mm on horizontalsides, 2 x ø20mm on vertical sides.
Single Gang – RadiusProd Code Depth PackMSCP2WH 2mm 20Size: 86 x 86mm O/A.
Single Gang – Adjustable LugProd Code Depth PackMSSB25WH 25mm 20Entries: 2 x ø20mm on each of 3 sides.
Single Gang – Adjustable LugProd Code Depth PackMSSB1WH 35mm 12Entries: 2 x ø20mm on each of 4 sides.
Single Gang – Fixed LugProd Code Depth PackMSSB2WH 35mm 12Entries: 2 x ø20mm on each of 4 sides.
ROUND CONDUIT ACCESSORY BOXES continued
COVER PLATES
FLUSH MOUNTEDACCESSORY BOXESWITH RADIUSCORNERS
All boxes have brass inserts andprovision for earth terminal which isseparately available.
Dimensions Fixing CentreSingle Gang 74 x 74mm 60.3mm TwinGang 134 x 74mm 120.6mmTo the requirements of BS 4662.
Twin Gang – RadiusProd Code Depth PackMSCP3WH 2mm 10Size: 86 x 146mm O/A.
Single Gang – Raised Prod Code Depth PackMSSP10WH 9mm 10Size: 85 x 85mm O/A.
Twin Gang – Raised Prod Code Depth PackMSSP20WH 9mm 2Size: 85 x 145mm O/A.
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Flush Mounted Single GangCover – Clip-onProd Code Depth PackMSCP1WH 5.3mm 20Size: 78 x 78mm O/A.
Single Gang – Radius CornersProd Code Depth PackMSSB7WH 19mm 20Entries: 1 x 16mm oval in topfor surface entry.Size: 87 x 87mm O/A.
Single Gang – Square CornersProd Code Depth PackMSSB12WH 25mm 20Entries: 2 x 16mm oval in topfor surface entry.Size: 87 x 87mm O/A.
Single Gang – Adjustable LugProd Code Depth PackMSSB6WH 16mm 20Entries: 2 x 16mm oval for EC017,1 x 20mm oval for EC018.Size: 74 x 74mm O/A.
Single Gang – Adjustable LugProd Code Depth PackMSSB1SOWH 35mm 12Entries: 1 x 20mm oval for EC018, 1 x 25mm oval for EC019.Size: 74 x 74mm O/A.
Twin Gang – Adjustable LugProd Code Depth PackMSSB3SOWH 35mm 6Entries: 1 x 20mm oval for EC018,1 x 25mm oval for EC019.Size: 74 x 134.3mm O/A.
Oval Bush (White)Prod Code Size PackMOCB20WH 20mm 25MOCB25WH 25mm 25
Oval Conduit Extra Super High Impact (White)Prod Code O.D. Dimensions PackEC016WH 13mm 13 x 8mm 50 x 3mEC017WH 16mm 16 x 10mm 50 x 3mEC018WH 20mm 23 x 11mm 50 x 3mEC019WH 25mm 29 x 11mm 20 x 3mEC020WH 32mm 32 x 11mm 20 x 3m
Straight Adaptors (in Nylon above, Black or white)Prod Code Size PackTFSA2WH 20mm 25TFSA3WH 25mm 25
PVC Corrugated Conduit (White)Prod Code O.D. PackMCC2WH 20mm 1 x 50mMCC3WH 25mm 1 x 50m
FLEXIBLE CONDUIT
CORRUGATED CONDUIT
Flexible Conduit (Black)Prod Code Size mm PackTF25BK 20 OD x 15.4 ID 1 x 5mTF225BK 20 OD x 15.4 ID 1 x 25mTF35BK 25 OD x 20.1 ID 1 x 5mTF325BK 25 OD x 20.1 ID 1 x 25m
Straight Adaptors (Black)Prod Code Size Thread Size PackTFSA2BK 20mm M20 x 1.5 25TFSA3BK 25mm M25 x 1.5 25Elbows (Black)TFEA2BK 20mm M20 x 1.5 10TFEA3BK 25mm M25 x 1.5 10
FLAME RETARDANTNYLON FLEXIBLECONDUIT
Manufactured from Flame RetardantNylon UL 94 VO-Rated. WorkingTemperature: -10°C to +120°C.Colour : Black
Channels (White)Prod Code Size PackECC21WH 13 x 8mm 50 x 2mECC22WH 25 x 9mm 50 x 2mECC23WH 38 x 9mm 50 x 2m
CABLE COVERS
Self Fixing Cable Cover (White)Prod Code Size Pack14000SFWH 29.5 x 10mm 10 x 3m14010SFWH 41.5 x 12.5mm 10 x 3mFor improved appearance andsecurity to surface cables.
Standard adaptors, couplers and saddles as listed on pages 120 and 121 may beused with corrugated conduit.
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The following notes are intended to be aguide to the installation of Marshall-TufflexPVC-U conduit and fittings. For further advicecontact our Technical Hotline 01424 856688.
CHOICE CONDUIT/CHANNELThe choice is dependent on the type of work beingundertaken and the specification. Heavy gaugeround conduit is normally used in surface work andfor casting in-situ. Light gauge round conduit issuitable for concealed work and in screeds. Ovalconduit is normally chosen for use in plasteredwalls and can be used as switch drops in surfacework. The channel sections are frequently used asan inexpensive method of installing cables indomestic installations beneath plaster. SeeMaterial Data page 208 for Thermal Properties.
SURFACE INSTALLATIONAll horizontal runs of conduit should be secured ata maximum distance of 0.9m and vertical runsshould be secured at a maximum of 1.2m. For highambient temperatures or where rapid changes intemperature are likely to be encountered thisdistance should be reduced. At fittings or wheredirectional changes takes place the conduit shouldbe fastened approximately 150mm either side tomaintain support. The fastenings should not beover tightened to permit thermal movement of theconduit.
JOINTS AND COUPLERSTo accommodate for thermal movement due totemperature change (Materials Data) on surfaceinstallations, it is recommended that expansioncouplings be used at a maximum distance of 6mintervals. Where high ambient temperatures orfrequent variations in temperature are likely tooccur this distance should be reduced.
Expansion couplers are installed with the short sidecoated with solvent cement and the couplerpushed firmly over the conduit down to theshoulder. The slip side coated inside with lubricantsealant receives the conduit to a midpoint to thenib. This will then permit expansion or contractionproviding the conduit is free to move in thesaddles.
Conduit fittings are installed in the system usingsolvent cement (MSC20) for permanentinstallations and lubricant sealant (MSC1) wherethe installation is subject to frequent changes.
CONDUIT
CONDUIT
CONDUIT
CONDUIT
EXPANSIONCOUPLER
EXPANSIONCOUPLER
LUBRICANTSEALANT – MSC1
CONDUITSOLVENTCEMENT – MSC20
BENDSNote: Care should be taken not to make too tight abend and attention is drawn to BS 7671:2001(Wiring Regulations) 522-08-03. The radius ofevery bend in a wiring system shall be such thatconductors and cables shall not suffer damage.
COLD BENDING 20-25MM CONDUITThis may be carried out on all conduit sizes up to25mm in diameter using the correct size and gaugeof bending spring. It should be noted that theheavy gauge spring is colour banded green and thelight gauge spring colour banded white near the tipof the spring. These springs are notinterchangeable under any circumstances. Makesure they are not damaged in any way as this cancause the conduit to kink and fracture makingremoval of the spring difficult.(In cold weather theConduit should be warmed by rubbing with a rag orsome other suitable means before bending.)
To bend the conduit insert the spring to the desiredposition, grip the conduit on either side of thebend and bring slowly together to form the bend.The bend should be made more acute thannecessary because of the tendency of the PVC-U to‘recover’ after bending. To remove the spring twistin an anti-clockwise direction which will reduce itsdiameter. At the same time turn the conduit in aclockwise direction gently pulling the spring andconduit apart. If the spring fails to release duringthis operation do not pull too hard otherwisedamage to the spring may occur. Repeat theremoval procedure turning the spring again in ananti-clockwise direction and rotating the conduitclockwise slowly pulling them apart. The conduitshould then be fastened into position to preventfurther ‘recovering’ of the bend.
HOT BENDINGThis should be carried out on all conduit above25mm diameter using the correct size and gauge ofbending spring. Insert the bending spring into theconduit as previously described, gently heating theconduit with a hot air torch, hot water or by othersuitable means, with care being taken to avoid thedirect application of a flame to the conduit. Whenthe conduit is in a pliable state, slowly bendaround a suitable former, holding in position forabout one minute until set when the bendingspring may then be removed by twisting in an anti-clockwise direction and gently withdrawing fromthe conduit.
If the conduit is bent too fast or, particularly in thecase of light gauge across the knee, there is a riskof damage to both the conduit and spring. Similarlyonce the bend has been made it should not beforced backwards but allowed to recover naturally.
EARTHINGThe properties of PVC-U make it an all insulatedsystem and the use of a separate earth cable isessential which greatly reduces the risk of poorearth continuity that can result from anybreakdown of joints which may occur in a steelsystem.
JOINT SEALANTSLubricant Sealant MSC1. For use with expansioncouplers or installations subject to frequentchange. Water resistant. Solvent Cement MSC20. A slow acting solventcement especially formulated for watertightconduit fittings.Solvent Adhesive MSC3. A watertight fast actingsolvent adhesive mainly for trunking systems withgood take-up properties.
In accordance with COSHH Regulations details ofour solvents are entered in The National PoisonCentre computer records. Health and Safety DataSheets are available from our Technical Departmentand are on the Marshall-Tufflex web site:www.marshall-tufflex.com
SPACER BAR SNAP SADDLEASSEMBLYSlide Saddle into groove until Saddle locks into the SpacerBar.
DISMANTLEInsert 4mm blade screwdriver into slot on side. Twistscrewdriver which releases the Saddle in the Spacer Barand slide Saddle out of the Spacer Bar groove.
LLSS
SSLL
SADDLE
SPACERBAR
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INTRODUCTIONThis appendix describes a method which can beused to determine the size of conduit necessary toaccommodate cables of the same size, or differentsizes, and provides a means of compliance withRegulations, which states ‘The number of cablesdrawn into conduit of a wiring system shall be suchthat no damage is caused to the cables or to theconduit during their installation.’
The method employs a ‘unit system’ each cable sizebeing allocated a factor. The sum of all factors forthe cables intended to be run in the same conduitis compared against the factors given for conduitin order to determine the size of conduit necessaryto accommodate those cables.
It has been found necessary, for conduit, todistinguish between –1. Straight runs not exceeding 3 metres in length,
and2. Straight runs exceeding 3 metres, or runs of any
length incorporating bends or sets.The term ‘bend’ signifies a British Standard 90ºbend and one double set is equivalent to one bend.
For the case 1, each conduit size is represented byonly one factor. For the case 2, each conduit sizehas a variable factor which is dependent on thelength of run and the number of bends or sets. Fora particular size of cable the factor allocated to itfor case 1 is not the same as for case 2.
Because of certain aspects, such as the assessmentof reasonable care of pulling-in, acceptableutilisation of the space available and thedimensional tolerance of cables and conduit, anymethod of standardising the cable capacities ofsuch enclosures can only give guidance on thenumber of cables which can be accommodated.
Thus the sizes of conduit determined by themethod given in this appendix are those which canbe reasonably expected to accommodate thedesired number of cables in a particular run usingan acceptable pulling force and with the minimumprobability of damage to cable insulation.
Only mechanical considerations have been takeninto account in determining the factors given inthe following tables.
As the number of circuits in a conduit increases,the current-carrying capacities of the cables mustbe reduced according to the appropriate groupingfactors. It may therefore be more attractiveeconomically to divide the circuits concernedbetween two or more enclosures.
Single-core PVC-insulated cables in straightruns of conduit not exceeding 3 metres inlength.For each cable it is intended to use, obtain theappropriate factor from Table A.Add all the cable factors so obtained and comparewith the conduit factors given in Table B.The conduit size which will satisfactorilyaccommodate the cables is that size having afactor equal to or exceeding the sum of the cablefactors.
TABLE ACable factors for short straight runs
TABLE BConduit factors for short straight runs
Conduit diam mm Factor20 46025 80032 1400
Type of Conductorconductor cross-sectional Factor
area mm2
1 22Solid 1.5 27
2.5 391.5 312.5 43
Stranded 4 586 8810 146
Single-core PVC-insulated cables in straightruns of conduit exceeding 3 metres in length, orin runs of any length incorporating bends orsets.For each cable it is intended to use, obtain theappropriate factor from Table C.Add all the cable factors so obtained and comparewith the conduit factors given in Table D, takinginto account the length of the run it is intended touse and the number of bends and sets in that run.The conduit size which will satisfactorilyaccommodate the cables is that size having afactor equal to or exceeding the sum of the cablefactors.
TABLE CCable factors for long straight runs or runsincorporating bends
TABLE DConduit factors for runs incorporating bends
Covered byTables A and B
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INTRODUCTIONThis appendix describes a method which can beused to determine the size of conduit necessary toaccommodate cables of the same size, or differentsizes, and provides a means of compliance withRegulations, which states ‘The number of cablesdrawn into conduit of a wiring system shall be suchthat no damage is caused to the cables or to theconduit during their installation.’
The method employs a ‘unit system’ each cable sizebeing allocated a factor. The sum of all factors forthe cables intended to be run in the same conduitis compared against the factors given for conduitin order to determine the size of conduit necessaryto accommodate those cables.
It has been found necessary, for conduit, todistinguish between –1. Straight runs not exceeding 3 metres in length,
and2. Straight runs exceeding 3 metres, or runs of any
length incorporating bends or sets.The term ‘bend’ signifies a British Standard 90ºbend and one double set is equivalent to one bend.
For the case 1, each conduit size is represented byonly one factor. For the case 2, each conduit sizehas a variable factor which is dependent on thelength of run and the number of bends or sets. Fora particular size of cable the factor allocated to itfor case 1 is not the same as for case 2.
Because of certain aspects, such as the assessmentof reasonable care of pulling-in, acceptableutilisation of the space available and thedimensional tolerance of cables and conduit, anymethod of standardising the cable capacities ofsuch enclosures can only give guidance on thenumber of cables which can be accommodated.
Thus the sizes of conduit determined by themethod given in this appendix are those which canbe reasonably expected to accommodate thedesired number of cables in a particular run usingan acceptable pulling force and with the minimumprobability of damage to cable insulation.
Only mechanical considerations have been takeninto account in determining the factors given inthe following tables.
As the number of circuits in a conduit increases,the current-carrying capacities of the cables mustbe reduced according to the appropriate groupingfactors. It may therefore be more attractiveeconomically to divide the circuits concernedbetween two or more enclosures.
Single-core PVC-insulated cables in straightruns of conduit not exceeding 3 metres inlength.For each cable it is intended to use, obtain theappropriate factor from Table A.Add all the cable factors so obtained and comparewith the conduit factors given in Table B.The conduit size which will satisfactorilyaccommodate the cables is that size having afactor equal to or exceeding the sum of the cablefactors.
TABLE ACable factors for short straight runs
TABLE BConduit factors for short straight runs
Conduit diam mm Factor20 46025 80032 1400
Type of Conductorconductor cross-sectional Factor
area mm2
1 22Solid 1.5 27
2.5 391.5 312.5 43
Stranded 4 586 8810 146
Single-core PVC-insulated cables in straightruns of conduit exceeding 3 metres in length, orin runs of any length incorporating bends orsets.For each cable it is intended to use, obtain theappropriate factor from Table C.Add all the cable factors so obtained and comparewith the conduit factors given in Table D, takinginto account the length of the run it is intended touse and the number of bends and sets in that run.The conduit size which will satisfactorilyaccommodate the cables is that size having afactor equal to or exceeding the sum of the cablefactors.
TABLE CCable factors for long straight runs or runsincorporating bends