ENCLOSURES FEATURE TOP TEN SPECIFICATION TIPS
Colin Newman, national sales manager for Legrand’s wiring devices business shares the company’s accredited CPD on industrial enclosures, and the top ten specification considerations
I
ndustrial enclosures, like so many electrical accessories for industrial
environments, are often viewed as generic, commodity items and specified largely on the basis of price. However, industrial enclosures are not installed merely to keep electrical equipment neatly tidied away, they must also support and protect electrical equipment. Inappropriate specification, therefore,
might not only reduce the service life of the enclosure itself but could also increase maintenance requirements or even compromise the integrity of the electrical installation and cause business interruption issues. Here are some key considerations that have to be taken into account in order to ensure correct specification for industrial enclosures.
LOCATION, LOCATION, LOCATION While all industrial installations call for a robust specification, the specific conditions of both the sector and the location of the enclosure must be considered when selecting the right product. The specification should consider whether there are any environmental chemicals present in the location and what these are, whether the enclosure will be located in a wash down area and whether it will be sited indoors or outdoors. If it’s outdoors, even factoring in whether the enclosure is in direct or indirect sunlight will have a bearing on the correct specification.
MATERIAL CONSIDERATIONS One of the reasons why understanding the specifics of the location is so important is that it will influence the
Above and below: inappropriate enclosure specification might not only reduce the service life of the enclosure itself but could also increase maintenance
requirements or even compromise the integrity of the electrical installation and cause business interruption issues
choice of enclosure material. In general terms, there are three options - mild steel, stainless steel or GRP. Mild steel is an ideal, cost effective option for non- corrosive commercial or industrial environments, offering good mechanical strength combined with ease of modification with cut outs. Stainless steel, meanwhile, is more suited to corrosive environments and facilities with rigorous hygiene regimes, such as the chemical and food processing industries, and it’s important to select the right grade of stainless steel (304 or 316) depending on the level of corrosion resistance required. For coastal and marine environments or locations exposed to intense direct sunlight, GRP is often the best choice, offering a lighter yet strong enclosure with excellent fire resistance and low thermal conductivity.
CORRECTLY CLASSIFIED Enclosures are classified with IP ratings to indicate the degree of protection provided against penetration of solid or liquid contaminants. IK ratings, meanwhile, indicate the level of protection against mechanical impact. Here, location must be part of the decision making process - if the enclosure is in a washdown area it will need an IP66 rating, for example, or in a heavy manufacturing environment, an IK10 rating may be required.
MOUNTING DECISIONS While most UK enclosures are delivered as standard with a plain ‘back’ mounting plate, European best practice favours perforated mounting plates. These enable quick mounting of DIN-rail, open slot panel trunking and transformers etc, whilst pre-drilled holes help to make installation more accurate and uniform, saving installation time, reducing the unit’s weight and exposure to corrosion risk and enhancing ventilation.
GOING MODULAR Modular chassis enclosures are a convenient option for easy mounting of DIN-rail equipment. Often supplied in kit form, the modular chassis can be custom assembled to meet a wide range of requirements, including retro-fit installations. A secure option for a safer and tidier installation, they feature a front cover that prevents exposure to live parts and can only be removed using a tool.
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PLINTHS AND ROOFS For some applications, it is advisable to specify an enclosure with a plinth and/or roof. A plinth can lift the installation off the floor to reduce the risk of rising water. It can also improve the working/access height for maintenance teams and may even avoid the need to build a concrete foundation. An enclosure roof, meanwhile, provides
pitched drainage for rainwater in exterior installations, protecting the enclosure gasket areas from contact with rainwater.
DOORWAY TO QUALITY Selection of the enclosure door will determine ease of maintenance and inspection. The wider the door, the easier it is to access the equipment inside for maintenance, and a glazed door enables a clear view of components without the need to open the enclosure. Specifiers should also consider whether the door is reversible, as this can be a useful feature in confined areas. Finally, they should check whether the product has doors with pre- installed section uprights as these can provide useful mounting holes for open slot panel trunking.
SPECIFYING IN SECURITY The enclosure’s locking system is important to protect the equipment from the elements and unauthorised access, so ensure that the lock maintains a weather- proof seal and, for larger enclosures, a dual lock may be advisable.
HEATING AND COOLING The temperature within the enclosure must be controlled by heating or cooling and the requirement should be based on the surface area of the enclosure, the maximum permissible temperature and the power dissipation of the equipment.
CERTIFIED SPECIFICATION The international certification and global approvals required will depend on the location of the installation but it’s important to ensure the chosen product has all mandatory approvals for the application. These could include UL, CSA, NEMA, Lloyds Register and Bureau Veritas.
Legrand
www.legrand.co.uk T: 0870 608 9000
Enter 209 ELECTRICAL ENGINEERING | MAY 2014 17
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