15.5.3 Cable trunking
Wherepracticableand material availabilityallows,as a general principle it is
recommendedthat for hygienicinstallationsthat the installershouldstandardise
on 304 stainlesssteeltrunkingand accessories.Cable trunking shouldbe of a
closedtypeand preferably haveno screws.Lidsshould be fittedwithclampsor
quickfittingsand should preferablyhavegaskets. Additionally, a proprietary
coverplate should be fixedovereachlid jointto reducethe ingressof soil.
Trunking should be keptout of wet areassinceit is difficultto maintain a high
degreeof protection fromwateringress.Theexteriorshouldhavea smooth
finishand be easyto clean.
The layout of the trunking installation shouldbe organised in sucha manner
that adequatecleaningwill be possible. Wheretrunkings are installedvertically,
the cableor cables withinshouldbe supported by a suitablemeansat appropriate
intervals in sucha manner that the conductor or cable doesnot sufferdamageby
its ownweight. For shortervertical distances conduits maybe used.In caseof
horizontal mounting specialattention should be given to ensure adequate
cleaning is practicable. Horizontaltrunking runsshould be keptto a minimum
because, being horizontal, theyoffera flat surfacefor accumulationof soil.
Horizontaltrunkingmounted hardup to the underside of a flat surface(e.g.a
ceiling)and sealedto it is an acceptable methodof installation.However,as the
trunking lid will be on the underside,cableretainers will haveto be employedto
retaincablesin the trunking withthe lid removed.
Wherea trunkingenters the hygienicproduction area,the openingremaining
after the passageof the trunking should be madegood withfire-resistant
material so as to maintain the degreeof fire resistanceas wellas the hygienic
standard of the respective element(wall, ceiling, etc.).Furthermore, the trunking
shouldbe internallysealedso as to maintain the degreeof fire resistanceof the
respective element.Trunkingshouldnot be mounted aboveareaswherethe
product is exposedopenlyto the environment. Thisrequirementis equally
applicable to all elements formingan electricalor control installation.
15.5.4 Conduits
Wherepracticableand material availabilityallows,as a general principle, it is
recommendedfor hygienicinstallationsthat the installershouldstandardiseon
304 stainlesssteel electricalconduitand accessories. Furthermore, the number
of differentsizedconduits shouldbe minimisedso far as reasonably practicable.
The conduit's exterior should havea smoothfinishand be easyto clean.The use
of pipe rather than conduit is discouraged because of the difficulties in
maintainingthe integrityof the pipingsystemat cableentries and exits(non-
availabilityof fittingsexacerbates this problem). Also,as pipetends to the thin-
walled,less physical/mechanical protectionis affordedby pipe.Furthermore,
sincelargerborepipes are generally selected, these,when usedfor vertical
drops, may lead to unsupported conductors or cables within sufferingdamage by
theirown weight. In short,whilethe use of pipe appearsto offeran aesthetically
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