Marshall-Tufflex Cable Management Catalogue

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TECHNICAL INFORMATION

Technical information

308 |

Conduit systems

522-08-03. The radius of every bend

in a wiring system shall be such that

conductors and cables shall not suffer

damage.

Cold bending 20-25mm conduit

Cold bending may be carried out on all

conduit sizes up to 25mm in diameter

using the correct size and gauge of

bending spring.

• Heavy gauge spring is colour-banded

green at the tip.

• Light gauge spring is colour-banded

white at the tip. Springs are not

interchangeable.

• Make sure springs are not damaged

in any way as this can fracture or kink

the conduit making removal of the

spring difficult.

• In cold weather, warm the conduit by

rubbing with a rag before bending.

To bend the conduit:

• Insert the spring to the desired

position, grip the conduit on either

side of bend and bring slowly

together to form the bend.

• Cold bending of 20mm and 25mm

conduit should be done with

correct / undamaged spring inserted

and bent over knee to initiate bend.

Spring should remain inserted until

the desired angle is achieved. (Under

no circumstance should bends be

increased or decreased without

correct spring inserted)

Failure to follow above procedure

could increase possibility of product

failure

• Make the bend more acute than

necessary to allow for PVC-U to

‘recover’ after bending.

• To remove the spring, twist anti-

clockwise (to reduce its diameter)

whilst turning the conduit clockwise

and gently pulling the conduit and

the spring apart.

• If spring fails to release, do not pull

too hard or damage to the spring

may occur.

• Repeat the removal procedure until

they come apart.

• The conduit should then be fastened

into position to prevent further

‘recovery’ of the bend.

Hot bending

Hot bending should be carried out on

all conduit sizes over 25mm in

diameter using the correct size and

gauge of bending spring.

To bend the conduit:

• Insert the spring to the desired

position as described in ‘cold

bending’, gently heating conduit

with a hot air torch, hot water or by

other suitable means.

• Avoid direct application of flame to

the conduit. When the conduit is in

a pliable state, slowly bend around a

suitable former, holding in position

for about 1 minute until set.

• Remove the spring, twist anti-

clockwise (to reduce its diameter)

whilst turning the conduit clockwise

and gently pulling the conduit and

the spring apart.

• If the conduit is bent too fast or,

in the case of light gauge conduit,

across the knee, there is a risk of

damage to conduit and spring. Once

the bend has been made, it should

not be forced backwards but allowed

to ‘recover’ naturally.

Earthing

The properties of PVC-U make it an

all insulated system and the use of a

separate earth cable is essential.

Joint sealant

• Solvent cement MSC is a slow acting

solvent cement especially formulated

for watertight conduit fittings.

In accordance with COSHH

Regulations, details of our solvents are

entered in The National Poison Centre

computer records. Health & Safety data

sheets are available from our Technical

Team or on the technical page of

the Marshall-Tufflex website:

www.marshall-tufflex.com

Spacer bar snap saddle

• Slide saddle into groove until it locks

into the spacer bar.

• To dismantle, insert 4mm blade

screwdriver into slot on side. Twist

screwdriver to release the saddle in

the spacer bar groove.

If conduit is installed in a corner, ensure

that the spacer bar snap saddle is fitted

with release mechanism facing away

from corner.

Material

PVC-U is flame retardant and self-

extinguishing. It provides a 100%

recyclable material with good

sustainability.

Installation

Fitting

• Secure horizontal runs of conduit at a

maximum distance of 0.9m.

• Secure vertical runs of conduit at a

maximum of 1.2m.

• In areas of high ambient temperature

or where rapid changes in

temperature are likely, these

distances should be reduced.

• Where there are fittings or directional

changes, the conduit should be

secured approximately 150mm either

side to maintain support.

• Avoid over-tightening to permit

thermal movement.

Joints and couplers

• To accommodate thermal

movement on surface installations,

it is recommended that expansion

couplers be used at a maximum

distance of 6m intervals.

• In areas of high ambient temperature

or where rapid changes in

temperature are likely, this distance

should be reduced.

• To install an expansion coupler, coat

the inside of the short side with

solvent cement (MSC) and push

firmly over the conduit down to the

stop point.

• Slide the next length of conduit into

the long side of the coupler until

mid-way to the stop point. DO NOT

GLUE INTO PLACE. This will permit

expansion or contraction of the

conduit, providing it is free to move

in the saddles.

Bends

Care should be taken not to make too

tight a bend and attention is drawn

to BS 7671:2001 (Wiring Regulations)

CONDUIT

EXPANSION

COUPLER

EXPANSION

COUPLER

LUBRICANT

SEALANT –MSC1

CONDUIT

SOLVENT

CEMENT –MSC20

PVC–U Conduit

SADDLE

SPACER

BAR

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Information