∑ sharp edges,recessedcorners, unevensurfaces, openhollows, unprotected
bolt threadsand screwsare minimised or avoided;
∑ inaccessiblespaces where product or soil mayaccumulate are not created;
∑ supports manufacturedfromrolledhollowsectionare totallysealed;
∑ brackets manufactured fromangleor channel are minimisedor avoided.
15.4.3 Cableladders and wire trays
Where practicableand material availabilityallows, as a generalprincipleit is
recommended thatfor hygienic installations the installer should preferably
standardiseon 304 stainlesssteelcableladdersor wiretraysand accessories.
The layoutof the cablerouteinginstallationshouldbe organisedin sucha
manner that allowsadequate cleaning. Where cable ladders or wire traysare
installed vertically,the cable or cables withinshouldbe supported by a suitable
means at appropriateintervals in sucha mannerthat the conductor or cabledoes
not sufferdamage throughits own weight. For shorter vertical distances conduits
maybe used.In the caseof horizontal mounting,specialattention should be
given to ensureadequate cleaning is practicable because, being horizontal, they
offer a flat surfacefor accumulation of soil.Horizontalcablewayscan be
installed vertically (on its side) to minimise the horizontal surface.
Where cableladdersor wiretraysenter the mediumhygieneproductionarea,
the openingremaining afterthe passage of the trunking shouldbe made good
withfire-resistantmaterial so as to maintainthe degreeof fire resistance as well
as the hygienicstandard of the respective element (e.g.wall,ceiling) (Fig. 15.3).
Cable laddersor wire traysshouldnot be mountedaboveareaswherethe
product is exposed to the environment.This requirementis equally applicableto
all elements forming an electricalor control installation.
15.4.4 Conduits
Where practicableand material availabilityallows, as a generalprincipleit is
recommended for hygienic installations that the installer should preferably
standardiseon 304 stainlesssteelelectrical conduitand accessories. Further-
more, the number of differentsized conduits shouldbe minimisedso far as
reasonablypracticable. The conduit's exteriorshould havea smoothfinishand
be easyto clean.
It is possible to run more thanone cablethrougha singleconduit.Whentwo
or morecables partlysharea commonroute, but go to differenttermination
points, the creation of unsealableopenings allowingthe cable(s) to enteror exit
the conduit is possible. For long,verticalwiringroutes,cableladders or wire
traysshould be used instead of conduit to preventthe conductor or cable
sufferingdamage by its ownweight. Conduitsystemsshouldprovide adequate
means of accessfor drawing in cables.The bending radiusof everybendin a
wiring systemshould be suchthat conductors and cablesdo not sufferdamage.
The conduit should be usedoversizedto allowfor wet cleaning. Openconduit
246 Handbookof hygiene controlin the foodindustry