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Enclosures Installation
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Sarel A Guide to Enclosure Selection & Installation
Selection of enclosures is generally regarded as a simple process,
determined by the requirement of size together with a passing, often
misguided reference to IP ratings. Enclosure technology, although
perceived as being relatively simple, is continually evolving to meet
the demands of new applications which not only raise new questions
concerning potentially adverse environmental conditions but which also
create the requirement for an increasing array of new features.
The materials of construction are in themselves a whole area of
technological involvement, with welded mild and stainless steels; hot
press moulded GRP and complex plastic mouldings in ABS, PVC,
polycarbonate, polystyrene etc.
Outdoor Sarel Enclosures Installation
In many instances the automatic choice for enclosures is mild steel
but the use of such enclosures outdoors is questionable but continues
for reasons which have little to do with the enclosure itself – cost,
convenience, habit and familiarity. All are valid reasons but each is
self-limiting, and still ignores the fact that steel rusts.
Despite the best in preparation, painting, plating and handling,
ultimately the corrosive propensity of the basic material may affect the
suitability of the application performance, which is, basically to
provide a protective envelope housing sensitive or potentially harmful
electrical equipment.
Mild steel enclosures therefore are not ideal, but they do offer
advantages and are apparently a cost-effective solution in many
instances. So what are the alternatives, and what can be done to improve
the chances of a successful installation with a mild steel enclosure
left alone to the mercy of the elements?
Use a corrosive resistant material instead; there is a wide range of
products, which Sarel can offer, principally glass fibre reinforced
polyester and stainless steel. Such materials drastically reduce or
completely eliminate problems of corrosion where conditions would be too
problematical for mild steel. One key additional advantage is that cost
differentials have narrowed over recent years. Moulding techniques and
material advances now ensure that GRP enclosures are of more than
adequate strength for most applications including street and trackside
furniture. They offer a measure of additional safety where vandalism is
concerned; a damaged steel enclosure can become live, a GRP one cannot.
For added strength, GRP enclosures such as root pillars are simply made
of thicker material with reinforcing ribs but without the weight
penalties of steel.
Consequently, in many cases where the capital cost is not the prime
consideration, use of a corrosion resistant product can be inherently
more satisfactory and can also work out cheaper by eliminating
maintenance costs.
Aspiration & Condensation
These two phenomena frequently combine to produce substantial
quantities of water within the enclosure. Aspiration occurs as a
consequence of rising and falling temperatures; when the daytime
temperature is high the air in the enclosure expands and some is
expelled – creating a partial vacuum; when the temperature falls, cool
moisture laden air is drawn in, and when it reaches its dewpoint the
moisture condenses and is deposited on components and the enclosure. The
whole process is cyclical and can eventually produce an incredible
amount of water.
The consequence, apart from the very real danger of electrical shorting,
is to cause internal corrosion in steel installations; correct use of
thermal management equipment can help prevent these problems.
Working On The Enclosure
The following are common sense tips, which can help to ensure a
successful installation:
- Inspect outer packaging on delivery as damaged wrapping may mean
the enclosure itself has been damaged in transit.
- Do not insert a knife into the packaging, e.g. to cut tape, as
there is a risk of scoring the paint finish.
- Do not drag the enclosure across workshop floors – use approved
lifting methods.
- Clear swarf from workbenches and make sure work surfaces are
free from debris.
- Empty the enclosure of any swarf or filings before installation
as condensation may corrode them.
- When marking out do not score paint surfaces.
- Repaint bared hole edges.
- Use sharp cutting tools to avoid cracking paint.
- Use punches in preference to drills.
- Seek manufacturer’s advice on care of seals and paint selection
before removing seals or overpainting.
- Remember all work should be such as to maintain the IP
integrity.
- Check the loading of equipment to be fitted, as distortions of
mountings or doors may affect the sealing.
- Final inspection should be conducted before transportation from
the workshop.
Site Installation
Ensure walls/floors are plumb and level and in good condition.
On external locations, site on the lee side of buildings where possible.
Canopies are recommended to deflect direct rainfall, as are pedestals to
raise enclosures from wet floors.
Floor standing enclosures which are not designed to be free standing
should be bolted back to a wall or stanchion for stability.
Cable entries must be supported outside the box, so that no stress is
caused to the enclosure, as deformation may degrade the sealing.
Earthing continuity should conform to relevant local standards.
The installation should comply with the relevant standards as specified
by the user. Selection of the enclosure should conform to the relevant
BS or equivalent standard.
A planned maintenance programme is advisable, checking gaskets,
paintwork, hinges, locks etc, for signs of physical damage, tampering or
corrosion.
Further Information
For further information on Sarel products, please contact us at:
Sarel, Unit C, Stirling Court, Stirling Road, South Marston Industrial
Estate, Swindon, Wiltshire SN3 4TQ.
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Sarel
Stirling Court
Stirling Road
South Marston Ind Estate
Swindon
Wiltshire
SN3 4TQ
Tel: 01793837430
Fax: 01793 837475 |