Complete electrical termination solutions for the mining industry are available from local manufacturer Pratley. Apart from individual products, Pratley can supply entire lighting circuits for mines, highlights Marketing Director Eldon Kruger. A typical mine has light fittings every 7 m, with Pratley being able to provide all the terminals and cable glands pre-fitted for any circuit length.
“It is a systematic way to connect lighting on-site in a mining environment. It is done quite efficiently by installing a catenary cable and then attaching LED lights that are now used due to energy efficiency requirements. The cable glands are adaptable, and everything is integrated with the junction box itself,” explains Eldon.
A circuit breaker can be included to allow the lights to be switched off quickly if a new fitting needs to be installed on-site. The mine can then return the light fitting to its workshop for repair so it can be used again. “It is a highly convenient and adaptable lighting solution for mines,” adds Eldon.
On the junction box side, Pratley’s Flameproof Ex d Envirobox®, which received the prestigious ‘Technical Product Innovation’ award from the South African Flameproof Association (SAFA), is ideal for hazardous mining environments.
Whereas, all traditional direct-entry flameproof junction boxes are made from steel, cast iron or aluminium, the Envirobox® is made from a specially formulated, robust engineering polymer unique to Pratley and is completely corrosion resistant.
The material has exceptional mechanical properties such as strength, stiffness, creep, and dimensional stability. As a result, the junction box can withstand 2 x 20-joule impact tests in a staggering -40°C environment.
It has also been third-party tested to a massive 4 000-kilopascal internal pressure. Additionally, it is IP66/68 certified for continuous underwater depths of up to 300 m, making it water, dust, and gastight. The lid and base have an accurately machined flamepath.
The flameproof Ex d Envirobox® can be supplied with either 4 x M20 or M25 entries or smaller upon request. It can accommodate Pratley Ex d flameproof cable glands and accessories and is therefore exceptionally versatile. Each box is supplied as a standard four-way box with two flameproof blanking plugs.
The internal bosses are drilled and tapped to provide an earthing point for terminal mounting rails or earth lugs. These are electrically connected to the box entries providing complete earthing continuity.
Boxes can be fitted with an N35 terminal rail, a Pratley patented Cranked rail, an inverted Cranked rail, or Piggyback rails. Pratley Kwikblok® terminals and pre-cut lengths of cable with glands can also be factory fitted to customer requirements.
An optional external earthing point and is supplied with 4 x M6 Nuts and washers as well as a M6 Spring washer. The junction box has threaded mounting M5 holes and can accommodate an indexable mounting plate that can be purchased separately if required.
The flameproof Ex d Envirobox® is fully certified to SANS, EN and IECEx Standards, including ATEX for use on surface and underground mining applications (Ex db I/IIB+H2 T6..T5 Mb Gb, Ex tb IIIC T85..T100 Db) in Zone 1, 2, 21 and 22 and an ambient temperature range of –40°C to +55°C.
“Our goal was to produce the only direct entry junction box that is corrosion resistant. The Pratley Flameproof Ex d Envirobox® marks yet another world-first product for Pratley,” concludes Eldon.