havingseveralcables terminatedto it, the enclosure shouldbe installedat least
30 mmfromthe wall, to prevent a soil trap beingcreated at the rear of the
enclosure.
It is importantthat cablinginstallations in mediumhygieneproduction areas
are given special attention and are well laid out, avoiding tangled cable
arrangements which may become breedinggrounds for vermin and pests.
Horizontalsurfacesshouldbe minimised. Furthermore, the installationshould
lookneatand be easyto clean. Joints between dissimilar metals (galvanic
action)should be avoided. Support equipmentand constructionsshouldavoid
any dead-ends. The use of conduitsreducesthe number of supports for cables.
Supportsare potentialplaces for the build-up of productand soil.
Individual cablesor multiplecablesof smalldiametersharing the sameroute
shouldbe installed in conduits or on wiretrays.Individualcablesthat do not
sharea commonroutewithother cables, are as hygienic as a single conduitrun.
However, a cableis usuallymore difficult to support in a hygienicmanner than
conduit.A cableis also at morerisk of being scuffed (whichwould resultin it
beingmore difficultto clean). Furthermore, should futuremodificationsto the
systemrequirethe addition of a cable,the installer maybe tempted to support
this newcablefromthe previouslyinstalledcable. Sucha practiceleadsto an
uncleanable and hygienicallyunacceptablecable bundle.The use of remote
input/output (I/O)and/or bus systemsis advisableas thesedecreasethe number
of cablesto be installed and,consequently, decreasethe number of potential
unhygienicsituations.
The number of separate connectionsto a singleitemor groupof itemsshould
be minimisedas far as is reasonably practicable. For example, mostsuppliers are
ableto design theirhygienic plant and equipment in sucha waythat onlyone
electricaland one air connection are required. A particular example is valves and
all valvemanufacturers should supplyvalves in sucha way that onlya singleair
and electrical connection is required, regardlessof the complexity of function of
the valve.
15.4.2 Supports
Cablesupport systems are potentialplacesfor the build-up of product and soil.
Therefore,support systems and constructionsshould be totally sealed,i.e. not
havingopenendswhere soil can accumulate. The use of wiretraysand conduits
reducesthe number of supportsthat wouldotherwisebe needed for individual
cables.
The material of constructionfor brackets shouldbe of hygienic material and
generally be the same as the equipment beingsupported (typically,cable
trunkings and conduits are preferably manufacturedfrom304 stainlesssteel,
unlessenvironmentalconditions requireotherwise,e.g. hightemperaturesor
potentialcontact withchlorine).
Supportsshouldbe constructed in sucha waythatadequate cleaning is
guaranteed by ensuringthat:
Improvingthe hygienicdesignof electricalequipment 245