When a customer encountered a problem with the removal of the restrained plug from the socket which posed a safety risk to underground mining personnel, Proof Mining Solutions, found an innovative solution. In collaboration with an end-user, Proof designed and developed a tamper proof spindle that prevents the restrained plug from being removed without first isolating the circuit.

Proof Mining Solutions is a customer-centric company that specialises in the design and manufacture of a range of flameproof, explosion proof and non-flameproof plugs, sockets, adaptors and cable couplers for the mining and tunneling industries.

“By listening to our customers and understanding their individual requirements, we are able to come up with bespoke solutions,” says Director, Donovan Marks.

Describing the previous plug design, Marks explains that it consisted of a standard lock that went through the end of the socket housing once the plug was inserted. “However, when it became evident that this design, which in effect stopped the plug from being removed without first isolating and removing the lock was not tamper proof, we simply had to find a better solution for our customer.”

“Following some research and consultations with our team of specialists, we, together with a large end user, engineered the perfect solution by developing a tamper proof spindle for our restrained plugs and sockets.” According to Marks, the design is similar to what is used on wheel nuts. “We have fitted the female section in the spindle and the male sprocket on the handle which is now loose. Thanks to this ingenious design, the plug can only be removed once the circuit has been isolated.”                       

“We have given each handle its own unique serial number to ensure that the handle supply is strictly controlled; the end user is able to log and issue these handles only to authorised personnel.”

Powermite’s restrained plugs and sockets, available in 300A-425A 1.1kV, 200A 1.1kV and 120A 1.1 kV are flameproof certified to SANS IEC60079-0-1 & SANS 1489 making them ideally suited for power supply to underground as well as surface-to-underground machines. The products feature copper grub screw or crimp type connectors, individually screened insulators and complete phase segregation.

The restrained plugs and socket range is also available in ProAlloy anti-theft material. In addition to being lighter in weight, the patented non-theft ProAlloy material is a mix of zinc, copper and aluminium which holds no resale value, thereby reducing the risk of theft.

Proof Mining Solutions supports its products with a complete after-market solution that includes coupler repair services, locally manufactured spares (ex-stock), product training as well as country-wide technical back-up and support 24/7 from certified Proof technicians. Services also extend to the terminating of plugs and couplers onto cables.