Sparks Electrical News

What constitutes a hazardous location? In some contexts it could be a badly lit step, however, we consider it an area in which a flammable material, gas or vapour must be mixed in the correct proportion with air, and within this mixture, a spark or heat is present, sufficient to ignite the mixture.

When light fittings and other electrical apparatus are to be installed in a hazardous area it is essential that the decision maker takes measures to reduce the likelihood of an explosion by the correct selection of the equipment to be installed in that area. As the gases and vapours liable to be present are rated according to ignition temperature, flash point and lower explosive limit, this information must be on hand when making your light fitting selection.

Installing equipment in hazardous lighting locations

Mineral insulated cables should be used to feed equipment installed in areas where vibration occurs. Rubber seals on gland assemblies should be checked to ensure correct seating and periodically to check for brittleness or deterioration. It is important at the design stage to anticipate what effect the chemicals present at the hazardous location will have upon the component parts of the installation. PVC, for example, will harden and crack when exposed to most solvents such as petrol, whilst general-purpose rubbers will soften when exposed to oils as well as solvents.

Damage to equipment can invalidate explosion proof qualities of cables and terminations, hence leading to a potentially dangerous situation especially in the case of flameproof equipment. Drilling holes in protected equipment to facilitate ease of mounting is definitely not permitted. Automatic electrical protection, earthing and the provision of effective means for complete circuit isolation, including the neutral, must be incorporated in the installation. Suitable wiring systems should be chosen and particular care must be taken in the connecting of cables to protected equipment. Unused entries in apparatus must be stopped off with suitable plugs according to the type of protection used.

Once the installation is complete, it has to be tested and this can be a problem because of the danger of creating a spark and igniting the inflammable atmosphere, thus any tests should be carried out when the location has been made safe i.e. by halting production.

Light fittings being only one of the electrical items used within the hazardous environment also need to be checked and serviced regularly and special care must be taken when relamping to see that machine faces are not corrosion pitted or gaskets damaged, that glands are still tight and not corroded, and finally, that the sealing screws and devices are all tightly replaced and none missing.



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Title: Editor
Name: Gregg Cocking
Phone: +27 11 622-4770
Fax: +27 11 615-6108

Title: Advertising Manager
Name: Carin Hannay
Phone: +27 11 622-4770
Fax: +27 11 615-6108