Regulation Part 5 - Electricity in Mines Flashcards
Cables installed in certain parts of a mine are required to be protected in a specific fashion.
What are the conditions that apply to the covering of the cable?
All cables are protected by a metallic covering & encloses all conductors.
Metallic covering must be:
- Electrically continuous
- Connected to earth
- Protected against corrosion
- Securely attached to equipment at each end
Cables installed in a mine are required to be protected by a metallic covering.
What are the five exceptions to this requirement?
- Trailing cable
- Extra low voltage cable
- Flexible cord less than 3m, permanently fixed to a portable apparatus.
- A cable used in float treatment as part of dredging.
- Telephone or signal cables.
List the specific matters which Regulations require each responsible person at a mine to ensure in relation to high voltage installations and operations.
- Before HV is installed, provide details of proposed installation to Electrical Inspector.
- Isolation of HV equipment is only carried out by a HV operator.
- Appointment of any HV operator is recorded in the record book.
- Correct safety equipment & PPE/C is used.
- Correct methods of work under electricity regulations are followed.
- No nearby plant is operated nearby without permit by an HV operator & required safety steps are done.
What do the Regulations require with regard to
(a) Earth continuity protection and monitoring?
(b) To what equipment does this Regulation apply?
(a) Each responsible person at the mine must ensure that for any piece of equipment, a system of monitoring the earth continuity automatically disconnects the electricity supply to a cable in the event of a break in the earth conductor.
(b) - Mobile equipment with trailing / reeling cables
- Any other equipment where the supply cable may be at risk.
- Any equipment connected by restrained plugs & receptacles.
The Regulations require that an electrical maintenance system is in place at the mine to ensure that electrical equipment and installations are maintained in safe working order.
What must be included in this maintenance system?
The maintenance system must include:
- Periodic examination and testing of all equipment and cables.
- Quarterly examination, testing & tagging of any portable apparatus.
- Routine testing of the effectiveness of earthing systems.
- Monthly testing of earth leakage protection devices.
- Tags used to identify the date of examination, testing and person who tested.
(a) The regulations require fire extinguishers to be provided near electrical installations. What are these places?
(b) The regulations require main switches to be provided in readily accessible places to control the supply of electricity. List three of these places.
(a) Fire extinguishers of appropriate type and size are kept:
- Near main switchboards and substations.
- At any other place an inspector requires.
(b) Main switches must be provided in readily accessible positions in; a quarry, dredge, construction site and an underground mine.
What do the Regulations pertaining to electricity require with regard to:
(a) Unauthorised access?
(b) Interference or damage?
(c) Size and type of fire extinguisher?
(a) Any room, enclosure or place used principally for electrical equipment is designed to restrict access by unauthorised persons.
(b) A person must not wilfully or negligently damage and without the authority of the manager, render any electrical cable, appliance or equipment.
(c) Fire extinguishers are of an appropriate type and size kept ready for use.
Each responsible person on a mine must ensure that an earth leakage protection device is provided for prescribed alternating current circuits.
What are the operating requirements for the device?
The earth leakage protection device must:
- Be set to operate immediately.
- Be readily accessible for testing the operation.
- Operate at a leakage current not exceeding:
- 30 milliamperes for circuits supplying portable apparatus
- 1 amperes for low voltage circuits
- 2 amperes for high voltage circuits
