PVC-U CONDUIT SYSTEMS

• 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.

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Code ColourWH WhiteBK Black

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Plastic PlugsProd Code Size PackMPP2 20mm H.G. 100MPP3 25mm H.G. 100MPP4 32mm H.G. 50MPP5 38mm H.G. 50MPP6 50mm H.G. 50

Straight CouplersProd Code Size PackMC2WH 20mm 100MC3WH 25mm 50MC4WH 32mm 25MC5WH 38mm 10MC6WH 50mm 10

Plain BendsProd Code Size PackMNB2WH 20mm 25MNB3WH 25mm 10MNB4WH* 32mm 20MNB5WH* 38mm 5MNB6WH* 50mm 2*Couplers required.

Expansion CouplersProd Code Size PackMEC2WH 20mm 25MEC3WH 25mm 10MEC4WH 32mm 10MEC5WH 38mm 10MEC6WH 50mm 5Should be fitted over a clear gapbetween two round rigid conduits. Uselubricant sealant in expansion side.

Inspection ElbowsProd Code Size PackMIE2WH 20mm 20For 25mm size use Inspection Bend

Inspection TeesProd Code Size PackMIT2WH 20mm 20MIT3WH 25mm 20

Inspection BendsProd Code Size PackMIB2WH 20mm 20MIB3WH 25mm 20

ReducersProd Code Size PackMR1WH 20 x 16mm 50MR2WH 25 x 20mm 50

ROUND CONDUIT FITTINGS

CONDUIT FITTINGS

Available in white (WH) or black (BK).

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Spacer Bar SaddlesProd Code Size PackMSB2WH 20mm 100MSB3WH 25mm 100MSB4WH 32mm 50MSB5WH 38mm 10MSB6WH 50mm 10

Spacer Bar Snap SaddleProd Code Size PackMSBS2WH 20mm 100

Locknuts (for use with Cable Glands)Prod Code Size PackMLN2WH 20mm 100MLN3WH 25mm 25MLN4WH 32mm 10

Threaded LockringsProd Code Size PackMLR2WH 20mm 100MLR3WH 25mm 50

Male BushesProd Code Size PackMMB2WH 20mm 100MMB3WH 25mm 100MMB4WH 32mm 25MMB5WH 38mm 10MMB6WH 50mm 10

Cable GlandsProd Code Conduit Size Cable Size PackMCG2WH 20mm ø7-10.5mm 100MCG2AWH 20mm ø4-7mm 25MCGP2WH 20mm (plain body) ø7-10.5mm 25MCGP2AWH 20mm (plain body) ø4-7mm 25MCG3WH 25mm ø8-13mm 25MCG3AWH 25mm ø12-18mm 25MCG4WH 32mm ø18-24mm 10

Round ‘U’ ClipsProd Code Size PackMMC2WH 20mm 100MMC3WH 25mm 50MMC4WH 32mm 25

Strap SaddlesProd Code Size PackMSS2WH 20mm 100MSS3WH 25mm 100MSS4WH 32mm 50MSS5WH 38mm 25MSS6WH 50mm 25

Adaptors (Female Thread)Prod Code Size PackMAB2WH 20mm 100MAB3WH 25mm 50MAB4WH 32mm 25MAB5WH 38mm 15MAB6WH 50mm 10

Adaptors (Male Thread)Prod Code Size PackMA7WH 20mm 100MA8WH 25mm 50

Adaptors (Clip-in Spout)Prod Code Size PackMCA2WH 20mm 100MCA3WH 25mm 50

ROUND CONDUIT FITTINGS continuedAvailable in white (WH) or black (BK).

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Terminal/Back OutletProd Code Size Pack2MRB7WH 20mm 203MRB7WH 25mm 10

Back OutletProd Code Size Pack2MRB1WH 20mm 203MRB1WH 25mm 10

TerminalProd Code Size Pack2MRB2WH 20mm 203MRB2WH 25mm 20

ThroughProd Code Size Pack2MRB3WH 20mm 203MRB3WH 25mm 20

AngleProd Code Size Pack2MRB4WH 20mm 203MRB4WH 25mm 20

TeeProd Code Size Pack2MRB5WH 20mm 203MRB5WH 25mm 20

4-WayProd Code Size Pack2MRB6WH 20mm 203MRB6WH 25mm 10

Through/Back OutletProd Code Size Pack2MRB8WH 20mm 203MRB8WH 25mm 10

Angle/Back OutletProd Code Size Pack2MRB9WH 20mm 203MRB9WH 25mm 10

Tee/Back OutletProd Code Size Pack2MRB10WH 20mm 203MRB10WH 25mm 10

4-Way/Back OutletProd Code Size Pack2MRB11WH 20mm 203MRB11WH 25mm 10

Loop-in BoxesProd Code Size Pack0MRB12WH Plain 202MRB12WH 4 x ø20mm KO 203MRB12WH 2 x ø25mm KO 20

Branch 2-Way or UProd Code Size Pack2MRB13WH 20mm 203MRB13WH 25mm 20

Branch 3-Way or YProd Code Size Pack2MRB14WH 20mm 203MRB14WH 25mm 20

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.

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Colour CodeSuffix




Circular Rubber Gasket (Black only)

Prod Code Size PackMRG1BK 66mm diam 100

Circular Lids Prod Code Size PackMCL1WH Flush fitting

(65mm diam) 100 MCL2WH Overlapping

(85mm diam) 100

Brass Earthing TerminalsProd Code Rating PackMET1 15 Amp 100

Circular Extension RingsProd Code Size PackMER1WH 12mm 20MER2WH 20mm 20MER3WH 25mm 20MER4WH 32mm 20MER5WH 38mm 10Circular Extension Rings have twolugs fitted with M4 brass inserts andtwo plain bored lugs.

CIRCULAR BOXFITTINGS



Colour CodeSuffix




SQUARE ADAPTABLECONDUIT BOXES

Available in white or black 32mm and38mm entries – internal box size 75 x75 x 60mm.

TerminalProd Code Size Pack4SJB1WH 32mm 15SJB1WH 38mm 1

ThroughProd Code Size Pack4SJB2WH 32mm 15SJB2WH 38mm 1

AngleProd Code Size Pack4SJB3WH 32mm 15SJB3WH 38mm 1

TeeProd Code Size Pack4SJB4WH 32mm 15SJB4WH 38mm 1

Four-wayProd Code Size Pack4SJB5WH 32mm 15SJB5WH 38mm 1


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Spacer Bar SaddlesProd Code Size PackMSB2WH 20mm 100MSB3WH 25mm 100MSB4WH 32mm 50MSB5WH 38mm 10MSB6WH 50mm 10

Spacer Bar Snap SaddleProd Code Size PackMSBS2WH 20mm 100

Locknuts (for use with Cable Glands)Prod Code Size PackMLN2WH 20mm 100MLN3WH 25mm 25MLN4WH 32mm 10

Threaded LockringsProd Code Size PackMLR2WH 20mm 100MLR3WH 25mm 50

Male BushesProd Code Size PackMMB2WH 20mm 100MMB3WH 25mm 100MMB4WH 32mm 25MMB5WH 38mm 10MMB6WH 50mm 10

Cable GlandsProd Code Conduit Size Cable Size PackMCG2WH 20mm ø7-10.5mm 100MCG2AWH 20mm ø4-7mm 25MCGP2WH 20mm (plain body) ø7-10.5mm 25MCGP2AWH 20mm (plain body) ø4-7mm 25MCG3WH 25mm ø8-13mm 25MCG3AWH 25mm ø12-18mm 25MCG4WH 32mm ø18-24mm 10

Round ‘U’ ClipsProd Code Size PackMMC2WH 20mm 100MMC3WH 25mm 50MMC4WH 32mm 25

Strap SaddlesProd Code Size PackMSS2WH 20mm 100MSS3WH 25mm 100MSS4WH 32mm 50MSS5WH 38mm 25MSS6WH 50mm 25

Adaptors (Female Thread)Prod Code Size PackMAB2WH 20mm 100MAB3WH 25mm 50MAB4WH 32mm 25MAB5WH 38mm 15MAB6WH 50mm 10

Adaptors (Male Thread)Prod Code Size PackMA7WH 20mm 100MA8WH 25mm 50

Adaptors (Clip-in Spout)Prod Code Size PackMCA2WH 20mm 100MCA3WH 25mm 50

ROUND CONDUIT FITTINGS continuedAvailable in white (WH) or black (BK).

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Terminal/Back OutletProd Code Size Pack2MRB7WH 20mm 203MRB7WH 25mm 10

Back OutletProd Code Size Pack2MRB1WH 20mm 203MRB1WH 25mm 10

TerminalProd Code Size Pack2MRB2WH 20mm 203MRB2WH 25mm 20

ThroughProd Code Size Pack2MRB3WH 20mm 203MRB3WH 25mm 20

AngleProd Code Size Pack2MRB4WH 20mm 203MRB4WH 25mm 20

TeeProd Code Size Pack2MRB5WH 20mm 203MRB5WH 25mm 20

4-WayProd Code Size Pack2MRB6WH 20mm 203MRB6WH 25mm 10

Through/Back OutletProd Code Size Pack2MRB8WH 20mm 203MRB8WH 25mm 10

Angle/Back OutletProd Code Size Pack2MRB9WH 20mm 203MRB9WH 25mm 10

Tee/Back OutletProd Code Size Pack2MRB10WH 20mm 203MRB10WH 25mm 10

4-Way/Back OutletProd Code Size Pack2MRB11WH 20mm 203MRB11WH 25mm 10

Loop-in BoxesProd Code Size Pack0MRB12WH Plain 202MRB12WH 4 x ø20mm KO 203MRB12WH 2 x ø25mm KO 20

Branch 2-Way or UProd Code Size Pack2MRB13WH 20mm 203MRB13WH 25mm 20

Branch 3-Way or YProd Code Size Pack2MRB14WH 20mm 203MRB14WH 25mm 20

Twin Through Way or HProd Code Size Pack2MRB15WH 20mm 203MRB15WH 25mm 10


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.

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Circular Rubber Gasket (Black only)

Prod Code Size PackMRG1BK 66mm diam 100

Circular Lids Prod Code Size PackMCL1WH Flush fitting

(65mm diam) 100 MCL2WH Overlapping

(85mm diam) 100


Circular Extension RingsProd Code Size PackMER1WH 12mm 20MER2WH 20mm 20MER3WH 25mm 20MER4WH 32mm 20MER5WH 38mm 10Circular Extension Rings have twolugs fitted with M4 brass inserts andtwo plain bored lugs.

CIRCULAR BOXFITTINGS



Colour CodeSuffix




SQUARE ADAPTABLECONDUIT BOXES

Available in white or black 32mm and38mm entries – internal box size 75 x75 x 60mm.

TerminalProd Code Size Pack4SJB1WH 32mm 15SJB1WH 38mm 1

ThroughProd Code Size Pack4SJB2WH 32mm 15SJB2WH 38mm 1

AngleProd Code Size Pack4SJB3WH 32mm 15SJB3WH 38mm 1

TeeProd Code Size Pack4SJB4WH 32mm 15SJB4WH 38mm 1

Four-wayProd Code Size Pack4SJB5WH 32mm 15SJB5WH 38mm 1


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Bending SpringsProd Code: Heavy Gauge Light Gauge Conduit

(Green end) (White end) Size PackMBSH2 MBSL2 20mm 1MBSH3 MBSL3 25mm 1MBSH4 MBSL4 32mm 1MBSH5 MBSL5 38mm 1MBSH6 MBSL6 50mm 1

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


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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 – 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 – 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



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.

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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 – 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



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.

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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

Oval to Round Adaptors (White)Prod Code Size PackMOR2WH 20mm oval/ 50

ø20mm

Oval Strap Saddle (White)Prod Code Size PackMOCSS20WH 20mm 50MOCSS25WH 25mm 50

Oval Connector (White)Prod Code Size PackMOCC20WH 20mm 25MOCC25WH 25mm 25

Oval Clips (White)Prod Code Size PackMOC1WH 13mm 100MOC2WH 16mm 100MOC3WH 20mm 100MOC4WH 25mm 100MOC5WH 32mm 100

OVAL CONDUIT

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FLUSH MOUNTED ACCESSORY BOXES

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Tees (Black)Prod Code Size PackTFIT2BK 20mm 5TFIT3BK 25mm 5

Sealing Washers (Black)Prod Code Size PackTFS2BK 20mm 50TFS3BK 25mm 50For straight Adaptors and Elbowsgiving the connection an IP66 rating.

Threaded Lockrings (PVC-U)(Black)Prod Code Size PackMLR2BK ø20mm 100MLR3BK ø25mm 50

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.

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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

For MT Supertube increase cable factor by 15%.


area mm2

1 16Solid or 1.5 22Stranded 2.5 30

4 436 5810 105

Length Conduit diameter, mmof run 20 25 32 20 25 32 20 25 32 20 25 32 20 25 32m Straight One bend Two bends Three bends Four bends1 303 543 947 286 514 900 256 463 818 213 388 6921.5 294 528 923 270 487 857 233 422 750 182 333 6002 286 514 900 256 463 818 213 388 692 159 292 5292.5 278 500 878 244 442 783 196 358 643 141 260 4743 270 487 857 233 422 750 182 333 6003.5 290 521 911 263 475 837 222 404 720 169 311 5634 286 514 900 256 463 818 213 388 692 159 292 5294.5 282 507 889 250 452 800 204 373 667 149 275 5005 278 500 878 244 442 783 196 358 643 141 260 4746 270 487 857 233 422 750 182 333 6007 263 475 837 222 404 720 169 311 5638 256 463 818 213 388 692 159 292 5299 250 452 800 204 373 667 149 275 50010 244 442 783 196 358 643 141 260 474

TABLE DConduit factors for runs incorporating bends

Covered byTables A and B

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PVC-U CONDUIT CABLE CAPACITIES

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


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

For MT Supertube increase cable factor by 15%.


area mm2

1 16Solid or 1.5 22Stranded 2.5 30

4 436 5810 105

Length Conduit diameter, mmof run 20 25 32 20 25 32 20 25 32 20 25 32 20 25 32m Straight One bend Two bends Three bends Four bends1 303 543 947 286 514 900 256 463 818 213 388 6921.5 294 528 923 270 487 857 233 422 750 182 333 6002 286 514 900 256 463 818 213 388 692 159 292 5292.5 278 500 878 244 442 783 196 358 643 141 260 4743 270 487 857 233 422 750 182 333 6003.5 290 521 911 263 475 837 222 404 720 169 311 5634 286 514 900 256 463 818 213 388 692 159 292 5294.5 282 507 889 250 452 800 204 373 667 149 275 5005 278 500 878 244 442 783 196 358 643 141 260 4746 270 487 857 233 422 750 182 333 6007 263 475 837 222 404 720 169 311 5638 256 463 818 213 388 692 159 292 5299 250 452 800 204 373 667 149 275 50010 244 442 783 196 358 643 141 260 474

TABLE DConduit factors for runs incorporating bends

Covered byTables A and B

20 Tech 9/6/04 5:21 pm Page 17

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PVC-U CONDUIT SYSTEMS