possible and preferablylimitthe number of connectionsto themto a practical
minimum. All connections(e.g.cableladdersor wiretrays, conduit, cable,air
tubes) to cabinetsor fieldboxesshould be made via the bottomsideof the
cabinet or fieldbox. The best way to makethe connection between the cabinet
or fieldbox and cableis to use a cablegland, completewithearthingtag (if
required, mountedinsidethe enclosure), locknutand shroud.
15.4.7 Cabinets
In general,cabinets shouldbe located outsidethe mediumhygienicproduction
area. For cabinetslocatedin hygienicproduction areas the requirements detailed
below apply.Where practicable and material availabilityallows, as a general
principleit is recommended for hygienicinstallationsthat the installershould
preferablystandardise on 304 stainlesssteelcabinets. However, coated mild
steel or plastic may be acceptable providedits exterior has a smooth finish that is
easyto clean.
Cabinetsshouldhavea minimumindexof protection of IP 55, allowing dust
to be removedfromthe enclosures'exteriors by watercleaning.Horizontal
surfacesshould be minimisedor avoided,by installinga sloperoofwitha
minimum of 30Î. The distancebetween the cabinetbaseand the floorshouldbe
no less than 100 mm (Fig.15.4).Where cabinets are wall mounted, the enclosure
should be installed at least 30 mm fromthe wall,to preventa soil trap being
created at the rear of the enclosure.
Temperature controlin cabinetsrequirespecialattention.Within hygienic
productionareasit is not advisable to vent the enclosure or to createan
additionalairflow sincethese can lead to microorganismsbeing transported
fromone pointto another in the area wherethey can infectthe equipment.Also,
an uncontrolledairflow froma non-hygienic environment(cabinet internals)
into a hygienicarea shouldbe avoided.For thesereasons the use of ventilators in
cabinetsshouldbe avoided,especially wherethe cabinet is located in close
proximity(within2 m) of the product.
The recommended alternativeis to make effective use of the self-cooling
capabilitiesof a cabinet by meansof creating an internal air circulation and
achievingtemperaturereduction throughthe cabinetsurface. If this does not
provide sufficient cooling, thenadditional coolingcould be providedby fixing
an air to watertypeheatexchangeto the cabinet.
15.4.8 Fieldboxes
Fieldboxesare frequentlylocated in hygienicproduction areas,and in such
circumstancesthe requirements statedbelowshould be strictly followed.Where
practicable and material availability allows, as a general principle it is
recommended for hygienic installations thatthe installer should preferably
standardise on 304 stainless steel field boxes. However, plastic may be
acceptableprovidedits exteriorhas a smoothfinish that can be cleanedeasily. A
248 Handbookof hygiene controlin the foodindustry