Hygienic cabling

Author: Ir. W.N.A. Burggraaf, Burggraaf & Partners B.V.
chairman of the National Working Group on Hygienic Cabling

Status 2024-08-05

The general regulation on the hygiene of foodstuffs (EU/ 852/2004) states that food premises must be clean and maintained well. The layout, design, and construction of these areas must be arranged so that cleaning and/or disinfection can be carried out appropriately.

In addition, in the preparation areas, surfaces in places where food is handled must be easy to clean. This means that smooth, washable, corrosion resistant, and non-toxic materials must be used, unless the operator can demonstrate that other materials are used are appropriate.

The surfaces that food comes into contact with are of primary importance, but the government has explicitly set additional requirements for all surfaces in preparation areas where products may be contaminated by the environment.

Cabling is used for each machine for the supply of electrical and/or pneumatic energy, but also for receiving and/or sending electromagnetic signals. Although this type of cabling does not come into direct contact with the food, it is subject to the same regulations, unless the operator can explicitly demonstrate that the currently chosen solution is sufficient.

To meet the minimum requirements, the working group on Hygienic Cabling, together with Dutch industry, has drawn up a practical guideline (only accessible when access has been ordered or granted). In this editorial there is an overview of the Guideline content.

The main rule is:

• avoid cabling in preparation areas,
• however, if this is not possible, only use hygienic cabling.

Hygienic cabling is possible through:

• minimizing the number of cables (by combining cables in a fully enclosed cable protection tube, also called conduit)
• application of a simple and completely cleanable system

In the past, various systems have appeared on the market, which ultimately turned out not to meet the minimum hygiene requirements:

• protective tubing (conduit) snapped and broke as a result;
• cable glands damaged by cleaning agent;
• vertical cable support systems with too many cross connections, which could not be cleaned adequately;
• cable ties that were difficult or impossible to clean at the back.

State of the art

The new generation of protective tubing, cable glands, cable fixings, and cable support systems, which were developed during and after the writing of the practical guideline, have completely eliminated the hygiene problems of the past.

Protective tubing and fittings

For hygienically wet, controlled wet, and dry cleaning of the field and machine cabling, a complete package is now available on the market thanks to various suppliers.

The IEC standard 61386 Conduit systems for cable management: Flexible conduit systems describes the following classifications of the conduit systems in 12 digits (in bold preferred value):

Digit	Subject	Value
1.	Compression	125 – 320 – 750 – 1250 – 4000 N
2.	Impact	0.5 – 1.0 – 2.0 kg from 100 mm height; 2.0 and 6.8 kg from 300 mm height
3.	Temperature lowest	1 = +5; 2 = -5; 3 = -15; 4 = -25; 5 = -45 °C
4.	- highest	1 = 60; 2 = 90; 3 = 105; 4 = 120; 5 = 150; 6 = 250; 7 = 400 °C
5.	Bending	1 = rigid; 2 = pliable; 3 = pliable/self-recovering; 4= flexible
6.	Electrical characteristics	0 = n.d.; 1 = bonding test; 2 = insulation test; 3 = both
	a. Bonding test	(no load voltage ≤ 12 V) resistance ≤ 0.1 Ohm
	b. Insulation test	(insulation in salt water) resistance > 5 MegaOhm
7.	Ingress solid objects	3 = < 2.5 mm; 4 = < 1.0 mm; 5 = dust; 6 = dust tight
8.	Ingress water	IP-class 2nd number (0-7) (wet cleaning: 7)
9.	Corrosion resistance	1 = low; 2 = medium; 3 = high inside; 4 = high
10.	Tensile strength	100 – 250 – 500 – 1000 – 2500 N no visible change in 2 minutes
11.	Flame propagation	1 = not; 2 = flame propagating
12.	Suspension	0 = n.d.; 20-30-150-450-850 N no visible change in 48 hours

Possible to test also:
- Flexing test
- Collapse test
- Electromagnetic compatibility: passive

The new protective tubes (conduits) are smooth, washable, and can no longer snap – even when they are empty – due to the special spiral wound inside. So, the tubes no longer leak, are chemically resistant, and are equipped with stainless steel fittings with hygienic sealing to the plug or box. The discussion regarding hollow spaces can now be closed (see section at the end).

Anamet has complemented its program of the hygienic Anaconda Sealtite FG protective tube (conduit) with all kinds of modular cable solutions. The Anaconda FG fitting is rated IP69K (protects against 40 bar water at 100 mm distance).

Because of its reducing width, the Anaconda fitting connects perfectly to the Harting F&B and HAN multi-connector without losing any of the throughput size.

And also offers maximum flexibility when connecting or disconnecting cable routes - especially during installation and maintenance.

The 90° elbow offers the possibility for tight linking to the cabinet or connection.

Special T pieces allow a smaller protective tube to branch off to another device. This makes it possible to combine water cooling for a video camera in a spray drying tower with the power supply and signal cable in a protective tube. Just before the camera, the water cooling is split off from the large protective tube.

It is possible to go from protective tube (UL certified food grade) to a fitting and to split off one or more cables.

The Anaconda food-grade blind plug is a hygienic seal of cable gland holes for future expansion in an electrical cabinet.

Products, see:
Anaconda flexible conduits
Hygienic conduits and multi-connectors
Hygienic conduit systems
Hygienic conduit - field connections 

Cable fixing and cable support systems

The fully stainless-steel cable support system lies flat or perpendicular to the wall, making it easily accessible from all sides and it can be easily wet-, controlled wet- and dry cleaned by using round rungs and round springs for the cable attachment.

The streamline HD ladder from the Niedax Group has been further refined. In addition to good hygiene, it also has the advantages of quick installation and assembly, and of quickly installing or replacing cables or protective tubes. This is possible by means of a spring and a removable rung. Thanks to the fixation by means of a spring, cable ties are no longer necessary. This means no more risk of plastic particles.

The standard width is 150, 300 or 500 mm. There is no point in being wider, because then the ladder is no longer easily accessible for manual cleaning even from the free side.

The standard spring is available in AISI 301 and in 50, 100, 150, 300 or 500 mm and is suitable for 4-16 mm (Ø33-5,5) or 6-32 mm (Ø48-8,0) diameter cables.

The streamline HD cable support system is designed for cabling within a device where fewer cables need to be routed. This system also eliminates the need for cable ties that are difficult to clean. Re-routing when replacing a cable to a field instrument can be realised quickly.

The length of the strip is 2 m. The cable holder and strip are available in 50, 75 and 150 mm height for 4-16 mm cable diameter (Ø33-5.5).

Products, see:
Streamline HD.
Streamline HD cable holder.

An alternative to the above options, which is only suitable for wet cleaning, are mounting brackets on the frame, which can hold the cables or protective tubes. The plate thickness must not exceed 3 mm and the diameter of the hole must be at least 4 mm larger than the diameter of the cable or protective tube. The supports, connecting the mounting brackets to the machine, are welded to the brackets, so there is a closed connection.

Section: Discussion hollow spaces

Discussion hollow spaces
Some companies have a strict policy to avoid all hollow spaces. For example, all frames must be solid and protective tubes are not allowed.
The reasoning is as follows: if the integrity of the outside of, for example, a tubular frame or protective hose is compromised, dirt will enter the hollow space uncontrollably and create an uncleanable space, which can potentially contaminate the environment. The contamination can be vermin or microbial.
The Machinery Directive explicitly states that non-cleanable areas must be hermetically sealed. This must be considered in the design, construction, cleaning and maintenance, and throughout the operating life of the equipment.
In its guideline 13 Hygienic Design of Open Process Equipment for Food, the EHEDG allows both systems: hollow and solid frame (figures 22.1 and 22.2). The welding technique at the time and the lack of discipline in the Technical Service sometimes showed that a hermetically sealed frame would nevertheless open due to cracks or drill holes. As a result, some food manufacturers have decided to stop using hollow parts. This reasoning fails to consider that solid parts can have surfaces that are not always easily accessible and therefore cannot be easily cleaned and visually inspected.
Other studies of the tubular frame show that, except in the case of snaps (visible), the tube will only tear on the weld seam if it is not sufficiently strong. New techniques with 3-D pre-lasering ensure that the forces on the inside of the pipe are supported and are no longer exerted on the weld. This means that the frame will never crack at the welds and will never leak again. The advantage of easy cleaning and visual inspection of pipe or box parts after cleaning now outperforms the solid parts.
However, if desired, a hollow frame can be provided with an approved brightly coloured red, green, or blue dye (with E number), dissolved in a food-grade lubricant. As soon as the frame fills up, especially with (cleaning) water, this dye is released.
The same rules apply to the new type of protective tube with hygienic fitting, which can no longer snap. It offers the same IP rating as the (hollow) junction box on the electric motor on one side and the (hollow) electrical box on the other side.