8/12/2019 Tailings Electrical Standard - Earthing - 16-05-2013

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VENETIA MINE1 NATIONAL ROAD MUSINA 0900

P O BOX 668 MUSINA 0900 TEL: +27 (0)15 534 9000 FAX: +27 (0)15 534 2019

www.debeersgroup.com

SUBJECT STANDARD ON ELECTRICAL INSTALLATIONS FOR THE TAILINGS

CURRENT OPERATING PRINCIPLE

There are two tailings streams namely DT1 and DT2.

On the end of the DT1 and DT2 streams are mobile sections (spreaders) which advancewhen the distributed area of operation is filled up. During advancing, additional stringersections are installed, conveyor belt lengths are increased and the electrical supply isextended. Due to the required advancing, a flexible trailing cable is utilized on the front end.

MINERALS REGULATIONS CHAPTER 21

21.14.1 Any cable other than a trailing cable, a cable of an intrinsically safe circuit or aflexible cable for moveable electric apparatus or portable electric apparatus shall beprotected by armoring if -(a) The cable is buried directly in the ground;(b) The cable is installed in such a position that mechanical damage may occur; or(c) There may be risk of igniting gas, coal dust or other flammable material.21.14.2 A flexible cable or trailing cable may be used only in connection with the operation of-

(a) Any self-propelled mobile machine which requires electric power to operate suchmachine;(b) Movable electric apparatus; or(c) Portable electric apparatus.21.14.3 Any flexible cable or trailing cable used in or on a mine or at a work shall bescreened either individually or collectively and such screens shall be earthed: Provided that acable used in a hazardous area shall be screened individually.21.14.4 No flexible cable or trailing cable shall have more than fifteen joint repairs, includingsheath patches over a length of 200 meters and no joint repair or patch shall be closer than 5meters to an adjacent joint, repair or patch and no joint, repair or patch shall be closer than 3meters to the cable plug or its terminal connection at the machine or apparatus.21.14.5 Any cable reel used in connection with a self-propelled mobile machine shall beprovided with a device which shall interrupt the power supply to the cable before thecomplete cable is unreeled so that at least one complete turn of the cable shall remain on thereel when the interruption of the power supply has been effected, unless the machinesmaximum range of travel is limited to less than that permitted by the cable on the reel forreasons other than the length of the cable.21.14.6 Any flexible trailing cable used in a hazardous area shall be -

TO All MTP Electrical Personnel

FROM Section Engineer Ore ProcessingDATE

16-05-2013

8/12/2019 Tailings Electrical Standard - Earthing - 16-05-2013

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VENETIA MINE1 NATIONAL ROAD MUSINA 0900

P O BOX 668 MUSINA 0900 TEL: +27 (0)15 534 9000 FAX: +27 (0)15 534 2019

www.debeersgroup.com

(a) Provided with an intrinsically safe pilot circuit which will prevent power from beingsupplied to the cable unless the earth conductor is in good working condition; and(b) provided with a means (system) to prevent arcing of power contacts of any plug used inconjunction with the cable while such plug is being inserted or withdrawn; and

(c) Connected to a supply on which the earth fault current is limited to prevent danger topersons.

STANDARD

1. Only individually screened flexible trailing cable with provision for a pilot wire systemshall be used on the spreader and advancing section of the conveyor belt installationFrom the mcc the installation shall have a separate 70mm2 bare copper earth wirewhich will be strapped to the cable racking.

2. The connection between the armoured cable and trailing cable shall be a 3 poleisolator. The earth shall be directly connected.

3. Flexible trailing cable next to fixed stringer installations shall not exceed 100m and bestrapped on cable racking on the stringers with temporary cable ties.

4. Between the fixed stringer sections and the mobile spreader unit a minimum length of12m 70mm2 flexible welding cable shall be connected to the structure and earthShould it reach the 100m mark, it shall be replaced with an armoured cable and theisolator of the armored cable be brought forward.

5. Only flexible cable jointing shall be used on the flexible trailing cable when extendingthe cable during advancement.

6. 1.2m electrodes shall be placed into the tailings and connected to the stringer verticalstructural member.. These electrodes shall be installed between 20 and 25m apart onthe vertical members with 25m distances between them being the absolute maximum.

7. Earth leakage protection shall be registered on the planned maintenance system andtested on a quarterly basis.

8. A victor plug with a pilot wire system to continuously monitor earth shall be in place.

CONCLUSION

It is recommended that as a long term solution this standard be put into practice and adheredto at all time in order to support our principle that safety is a core value.