use of conduits reducesthe numberof supportsfor cables. Supports are potential
places for the build-up of productand soil.
Where multiple cablesdropfromthe ceilingserviceareainto the hygienic
productionarea, cable trunkingshouldbe considered.Individual cablesor
multiple cables of smalldiameter sharing the same routeshould be installed in
conduits. If cablesare to be installed in rigid conduit, thenfinalconnections to
plant thatis subjectto vibration(e.g.motors)shouldbe madevia flexible
conduit (havinga smooth outersurface) or by someother suitable means.
Individualcables that do not share a commonroutewithothercablesare as
hygienic as a singleconduit run. However, a cableis usually moredifficultto
support in a hygienicmannerthanconduit. A cableis also at morerisk of being
scuffed (whichwouldresultin it beingmore difficult to clean).Furthermore,
should futuremodificationsto the system requirethe additionof a cable, the
installer maybe tempted to supportthis new cablefromthe previously installed
cable. Sucha practice leadsto an uncleanable and hygienicallyunacceptable
cable bundle.The use of remoteI/O and/orbus systemsis advisableas these
decreasethe numberof cables to be installedand,consequently,decreasethe
number of potentialunhygienicsituations.
The numberof separate connectionsto a single itemor groupof itemsshould
be minimised as far as is reasonablypracticable.For example, most suppliers are
ableto designtheirhygienicplantand equipmentin sucha waythat onlyone
electricaland one air connection are required.A particular example is valvesand
all valve manufacturersshouldsupply valvesin sucha way that onlya singleair
and electricalconnection is required, regardless of the complexityof functionof
the valve.
15.5.2 Supports
Cable supportsystemsare potentialplacesfor the build-up of product and soil.
Therefore,supportsystems and constructionsshouldbe totallysealed,i.e. not
having openendswheresoil can accumulate. The use of cabletrunking and
conduits reduces the number of supports that would otherwise be neededfor
individualcables.
The material of construction for brackets should be of hygienicmaterialand
generally be the sameas the equipment beingsupported (typically,cabletrunk-
ingsand conduits are manufacturedfrom304 stainless steel,unless environ-
mental conditionsrequireotherwise, e.g. hightemperatures or potentialcontact
withchlorine).
Supportsshould be constructedin sucha waythatadequate cleaningis
guaranteedby ensuring that:
∑ sharp edges,recessedcorners, unevensurfaces, openhollows, unprotected
bolt threadsand screwsare avoided;
∑ inaccessiblespaces where product or soil mayaccumulate are not created;
∑ supports manufacturedfromrolledhollowsectionare totallysealed;
∑ brackets manufactured fromangleor channel are avoided.
252 Handbookof hygiene controlin the foodindustry