Earthing: SANS versus the Electrical Machinery Regulation

July 31st, 2014, Published in Articles: Vector

 

It has became apparent over the last few years that we as contractors run the risk of not doing proper testing. This often leads to fatalities, yet we overlook the need to address the problem.

As though this were not enough, we can’t even align the SANS 10142-1 with the Electrical Machinery Regulation Act 2011.

Say, for instance, we look at earthing under regulation 6.12, Earthing (SANS 10142-1), and then at Regulation 18, Earthing (Electrical Machinery Regulation Act 2011):

6.12.3.2 The following conductive parts do not need to be earthed:

  • Short unexposed lengths of metallic wireway used to protect wiring as it passes through a building element.
  • Exposed conductive parts of fixed electrical equipment out of arm’s reach from the floor or walking level, out of arm’s reach from structures bonded to earth, and not exposed to the weather or to the condensation, dripping, splashing or accumulation of water, and not touching a conductive surface.
  • Conductive parts that cannot be touched by the standard test finger.
  • Fixings such as cleats, clips, saddles and clamps.
  • Equipment and appliances permanently connected to safety supplies.
  • Small parts such as screws or nameplates that are isolated by insulating material.
  • Structural steelwork, including items such as fire escapes and cat ladders.
  • Metallic fittings in bathrooms if they are isolated from earth (see 7.1.5).

Let us us consider “arm’s reach”, which is determined by the following distances measured from a surface to be occupied by people:

  • 2,5 m vertically upwards.
  • 1,25 m vertically downwards from the outer edge of the surface.
  • 1,25 m horizontally outwards from the outer edges of the surface.
  • 0,75 m horizontally inwards from the outer edges of the surface and underneath the surface.

This does not necessarily mean actually from floor-level as the annex states “surface expected to be occupied by persons”. This can be a cherry picker or it can mean “from the surface-up” from were the crane control box is.

Regulation 18: Earthing, Electrical Machinery Regulation 2011

Employers or users shall cause roofs, gutters, downpipes and waste pipes on premises to which electrical energy is supplied to be earthed, except:

Where the operating voltage does not exceed 50 V.

Roofs made of non-conductive material or metal roofs covered by non-conductive material.

Gutters, downpipes and waste pipes made of non-conductive material or gutters and downpipes attached to metal roofs covered by non-conductive material.

Roofs, gutters, downpipes and waste pipes on premises which receive electricity by means of underground service connections, provided that the connection is to the conductive structures.
All accessible metallic parts of electrical machinery which, although not normally part of electrical circuits, may become live accidentally. These are to be protected by insulating coverings or enclosed or earthed, and the resistance of the earth continuity path shall not exceed 0,2 OHM, except:

  • Metal in earth-free situations, other than runs of metal wireway and the close-fitting metal sheathing and armouring of cables.
  • Short, separate lengths of heavy-gauge metal wireway used for the mechanical protection of cables not used in the secondary circuits of discharge luminaire installations.
  • Short, unexposed separate lengths of metal wireway used for the mechanical protection of insulated wiring passing through walls, floors, partitions or ceilings.
  • Metalwork on fixed electrical machinery more than 2,4 m above the floor. This exception shall not apply where such metalwork is situated in any position likely to become damp; in elevator shafts; near rotating machinery, or in contact with walls, ceilings or other support constructed of or covered with conducting material.
  • Metal parts of electrical machinery enclosed or shrouded by insulating material so that they cannot be touched.
  • Cleats, clips, saddles or clamps of other devices for fixing wireways and cables.
  • Shades, reflectors and guards supported on lamp holders or discharge luminaires.
  • Lamp caps.
  • Metal parts of or screws in or through non-conducting materials which are separated by these materials from energised parts and from earthed, non-energised parts in such a way that they cannot become live that or come into contact with earthed parts in normal use.

Should the power supplier or inspector find, through a test of the electrical machinery on a premises, that exposed metallic parts of the installations are not earthed, the supplier or inspector shall require the occupier or owner of the premises to effect the necessary earthing within 30 days. Should the occupier or owner fail to comply, the power supplier may disconnect the electrical energy to the premises and will not reconnect the power until the earthing has been done.

Which would be used in a court of law in the case of a fatality? SANS 10142-1 or the Electrical Machinery Regulation Act? Both will we used but the decisive legislation will be applicable. This is clear in sections 43 and 44 of the Occupational Health and Safety Act 85 of 1993.

This is a problem I come across in 80% of my inspections. We can use a simple tool to test for earth problems when we conduct an inspection and test for compliance: we must do what is needed to keep safe and also to keep others safe.

Contact Nico van den Berg, Independent Electrical Inspection Services, Tel 079 986-4647, info@independent-inspectors.co.za

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