Local manufacturer Pratley offers complete electrical termination solutions for the mining industry. Marketing Director Eldon Kruger highlights that, as well as individual products, Pratley can supply entire lighting circuits for mines. A typical mine has light fittings every seven metres, and Pratley can provide all the terminals and cable glands pre-fitted for any circuit length.
“This 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, which are now used for their energy efficiency. The cable glands are adaptable, and everything is integrated with the junction box,” Kruger says.
A circuit breaker can be included to allow the lights to be switched off quickly if a new fitting needs to be installed. The mine can then return the light fitting to its workshop for repair so it can be used again. “The system offers mines a convenient and adaptable lighting solution,” Kruger adds.
For the junction boxes, Pratley’s Flameproof Ex d Envirobox®, which last year received the ‘Technical Product Innovation’ award from the South African Flameproof Association (SAFA), is ideal for hazardous mining environments.
Whereas 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 completely corrosion resistant.
The material has exceptional mechanical properties such as strength, stiffness, creep, and dimensional stability and the junction box, consequently, can withstand 2 x 20-joule impact tests in a -40°C environment.
It has also been third-party tested to withstand an internal pressure of up to 4 000 kilopascals, and it is IP66/68 certified for continuous underwater depths of up to 300 m, confirming it is water- dust- and gastight. The lid and base incorporate an accurately machined flamepath.
The flameproof Ex d Envirobox® can be supplied with either 4 x M20 or M25 entries or smaller, on request. It can accommodate Pratley Ex d flameproof cable glands and accessories and is therefore particularly 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 is available 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 in surface and underground mining applications (Ex db I/IIB+H2 T6..T5 Mb Gb, Ex tb IIIC T85..T100 Db) in Zones 1, 2, 21 and 22 and an ambient temperature range of -40°C to +55°C.
For more information visit: www.pratleyelectrical.com
