Interference and Hazards
Key Issues
118. The quality of telecommunications services can be adversely affected due to interference from power lines. The impact on the quality of a service provided by another was raised by telecommunication operators during the recent consultation on extending the access regime for electricity works above 110 kV and 100 MVA on roads and level crossings.
119. Key Issues:
Do the current legislation and regulations adequately ensure that the quality of a service provided by one utility is not adversely affected by the activities of another?
Do the current legislation and regulations adequately provide effective means of addressing safety issues related to the management of hazards to equipment and people?
Discussion
Interference between Electricity and Telecommunication Services
120. In a submission to the Local Government and Environment Select Committee on the Resource Management Act and Electricity Legislation Amendment Bill, concerns were raised over the interference caused by electricity works to telecommunications lines in the form of "hazardous induction" and "noise". It was suggested that the current utilities legislation and regulations do not adequately provide for managing these risks.
121. Both electricity operators and telecommunications operators share the road corridor to locate their network and nearly every road in New Zealand has both a telecommunications and electricity line located in its corridor - either aerial or buried. It has been suggested that where electricity works that carry an earth fault current run parallel to, or cross over (at any angle other than a right angle), a telecommunications line,17 a possibly hazardous voltage can be induced along the telecommunications cables' conductors. Earth fault currents can be limited on lower voltage lines (e.g. 11 kV, 22 kV, and 33 kV) by using neutral earthing resistors, however, it is suggested that these are impractical at voltages higher than 66 kV.
122. A serious safety hazard is also posed by failures at a concrete pole, steel pole, or steel pylon, predominantly from, but not limited to, high voltage works. It was submitted that "if such a failure results in a phase to pylon (or conductor to pole) fault, a very high earth potential rise could occur. In turn, this may cause very high voltages in the ground surrounding nearby telecommunications cables or ready access points." It is suggested that this could result in degradation of the telecommunications plant's insulation and allow hazardous fault voltages into the telecommunications network. Potentially, this could damage telecommunications equipment and electrocute utility workers or even people when they pick up a phone.
123. A further problem submitted was the issue of service quality affected by "noise" induced from harmonic currents from high voltage (110 kV and 220 kV) lines located along public roads, and the exacerbation from adding 66 kV and 100 kV lines along the same corridor. Noise problems experienced include: "audible noise so loud that customers have to shout to communicate; calls being cut off; reduced transmission speeds; intermittent or delayed faxes; and slow and/or unreliable internet access, severely limiting email and other internet based services". Both issues can also cause significant business costs through damage to utility networks and equipment.
124. The Electricity Regulations 1997 (regulation 58), provide for electrical interference with telecommunications lines and notes:
- Where any telecommunications lines, or any other structure, device, or thing, designed or intended for use for telecommunications purposes, is being constructed in the vicinity of any works or electrical installation, the person constructing the lines, structure, device, or thing must ensure that the lines, structure, device, or thing is constructed so as to ensure that electricity conveyed through the works or electrical installation does not cause any induced voltage, earth potential rise, or shock currents, that is or are likely to cause damage to the lines, structure, device, or thing or a hazard to persons.
- Where any works or electrical installation is being constructed in the vicinity of any telecommunications lines, or any other structure, device, or thing, designed or intended for use for telecommunications purposes, the person constructing the works or electrical installation must ensure that the works or electrical installation is constructed so as to ensure that electricity conveyed through the works or electrical installation does not cause any induced voltage, earth potential rise, or shock currents, that is or are likely to cause damage to the lines, structure, device, or thing or a hazard to persons.
125. While these regulations address the issue of interference in terms of the hazards of induced voltage, earth potential rise, and shock currents, there is no provision for interference affecting service quality, such as "noise" interference. The terms "interference" or "service quality" are not mentioned specifically in the regulations.
126. The Transit New Zealand Act 1989 (section 53 Poles, etc., on roads to be adjacent to boundaries) notes that a pole or tower cannot be erected or re-erected without having regard to ….(b) The necessity of ensuring that any telecommunications line or electricity transmission line is not susceptible to instability or to damage by, or interference from, natural causes, or trees or structures or other lines or transmission lines.
127. The Radiocommunications (EMC Standards) Notice 2004 No. 2 lists the New Zealand standard NZS 6869 Limits and measurement methods of electromagnetic noise from A.C. power systems. We understand that these standards are not applicable to interference attributable to induced voltages.
128. The NZCCPTS has developed a number of guides aimed at mitigating/preventing interference between electricity and telecommunications technologies. Key Guides include:
- Guide for Investigations and Mitigating Power System-Telecommunication System Noise Interference
- Application Guide for Single Wire Earth Return (SWER) High Voltage Power Lines for the control of interference to telecommunication circuits
- Cost Apportioning Principles for the Mitigation of Hazards and/or interference between Power and Telecommunication Systems
- Application Guide for cable-sheath bonding for the control of earth potential rise and for the limitation of hazardous induction into telecommunication circuits.
129. While these regulations, standards, and guidelines provide some guidance and statutes provide some limited statutory safety provisions, there is still concern that there is limited communication from electricity operators to telecommunications operators regards alteration and upgrading of existing works. In the recent consultation to the Local Government and Environment Select Committee on the Resource Management Act and Electricity Legislation Amendment Bill, it was submitted that under section 24 of the Electricity Act 1992, communication be made mandatory between electricity operators and other utility operators who would be affected when electricity operators "alter the electrical characteristics of any works".
130. As the legislation currently stands, electricity operators must notify affected parties (including telecommunications operators) of the intention to construct, alter, remove, or repair electricity works within the road corridor. It was submitted that the current clauses do not cover the intention to "alter the electrical characteristics of any works", and therefore reasonable conditions cannot be imposed by an affected party based on the effects of a change of electrical characteristics. For example, notification should cover such changes as replacing a wooden pole with a concrete pole as this significantly alters the conductivity properties of the pole and the effects on nearby utilities. While regulation 57(1) of the Electricity Regulations provides that "no person supplying electricity or line function services may alter the electrical characteristics of the supply system in a way which may cause danger to persons or property" and regulation 57(2) covers reasonable steps to ensure fault currents are limited to reasonable levels, it is felt that these do not provide the same protection as the ability for affected parties to impose reasonable conditions.
131. It was submitted that a minor amendment be made to section 24 of the Electricity Act 1992 to clarify the notification and imposition of reasonable conditions for the alteration of electrical characteristics of any works. The Ministry supports this proposition and thus makes it a proposal below.
Interference between Utilities
132. It must also be noted that on occasion, one utility may interfere with another utility within the road corridor. The prominent example is the flooding of storm water and wastewater pipes, causing flooding and damage to other utilities (roads, telecommunications, gas, and electricity).
The Management of Hazards to Equipment and People
133. Within the broader issue of interference, the issue has been raised regards the management of hazards to equipment and people from utility works within the road corridor. Specific concerns have been raised regarding the lack of formalised mapping of utility networks within the road corridor and the ability to check before you dig. Utility operators are concerned about the lack of effective means to ensure that utility operators working in the road know the location of other utility networks and avoid inadvertently digging into another utility network. For example, the case of a telecommunications operator digging and fracturing a gas pipe they did not know was there. Utility operators cite specific concerns about accidentally digging into buried high voltage cables and the risks this poses to workers.
134. An effective means of addressing safety issues could be the development and use of a safety code of practice between organisations to cover safety issues. This could outline best practice approaches to checking with other utilities as to the locations of networks in the proposed work area during the notification period. This is an option for industry and local government to develop.
135. Another option is a formal database mapping utility networks and available for utility operators to plan proposed works against for issues of interference with other utility networks. The question is who would manage and coordinate such a system? Should the RCA or local authority, or a private enterprise manage such a system? The management of such a system by the local authority is discussed in the next section addressing strategic planning and coordination of utility works in the road corridor.
136. Concerns have also been raised about the safety of utility workers working within the road corridor. Work sites involving utility structures on roads are adequately covered by the Code of Practice for Temporary Traffic Management.
Proposals
That s24 of the Electricity Act 1992 be amended to clarify the notification and imposition of reasonable conditions for the alteration of electrical characteristics of any works:
24. Construction or maintenance of works on roads-
(1) Except as provided in subsection (2) of this section, an electricity operator may from time to time construct and maintain works in, on, along, over, across, or under any road, and for any of these purposes may-
(a) Open or break up any road:
(b) Alter the position of-
(i) Any pipe (not being a main) for the supply of water or gas; or
(ii) Any telecommunications line; or
(iii) Any works-
that are constructed in, on, along, over, across, or under that road:
(c) Alter, repair, or remove any works so constructed or maintained, or any part of any such works.
[(d) Alter the electrical characteristics of any works.](2) No electricity operator shall exercise the powers contained in subsection (1) of this section otherwise than in accordance with such reasonable conditions as may be prescribed by-
(a)The local authority or other body or person having jurisdiction over the road; and
(b)The owner of the pipe, telecommunications line, or works, as the case may require.[(b) The owner of any pipe, telecommunications line, or works that are constructed in, on, along, over, across, or under the road and that will be affected, or may be affected, by the works.]
Questions to Consider
What solutions do respondents consider would best improve the management of interference between utilities?
What solutions do respondents consider would best improve the management of hazards to equipment and people from utility works within the road corridor?
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