Ensuring switchboards deliver safe electricity

Late last year, Energy Safe Victoria (ESV) issued a ‘Safety Alert’ to warn the community of the importance of installing safety switches in premises and ensuring that all electrical equipment is in good condition and not damaged in any way. It was issued following the death of a man in the state’s east, whose body was found in his garage still clutching a damaged extension-lead socket. He would have been saved if a safety switch had been installed on the power circuit.

Safety switches have been a standard inclusion in Australian switchboards for many years, being widely recognised as a critical safety element in power circuits for domestic, commercial and industrial installations. To raise the awareness of the benefits of safety switches, there have been many initiatives and campaigns with both consumers and the electrical industry at large.

The state and federal governments have provided incentives to consumers to upgrade their switchboards to include safety switches and have conducted extensive advertising campaigns to promote the benefits of having safety switches installed in homes and businesses. From the electrical industry’s perspective, all electricians have had it drilled into them to always install safety switches in switchboards.

Despite all that information being put out into the electrical industry and the wider community, we still hear of tragedies like the one in the introduction of this article. So, as I conducted research for this article on switchboards, I looked for guidelines, instructions and reminders that we, as the electrical industry, can adopt to actively ensure consumers and tradespeople alike are not unnecessarily exposed to the hidden dangers of earth leakage.

ESV Safety Alert

Commenting on the fatality mentioned in the introduction, the ESV Safety Alert outlined the conditions in the garage where the man died - no safety switch on the power circuit, an earthen floor which was extremely wet in certain parts, the victim was not wearing shoes or socks and the socket of the extension lead was damaged and in very poor condition. It was nothing short of a recipe for disaster.

The Safety Alert presented some simple, yet critical precautions for both consumers and electricians to adhere to, in order to avoid such a disaster occurring again:

• Ensure that safety switches are installed on the power and lighting circuits in all properties;
• Make sure that all electrical equipment, including extension leads, is in good condition and not showing any signs of damage;
• If in doubt about the condition of any equipment, discard it and ensure the item cannot be re-used or recycled by others;
• Install permanent power points in properties - extension leads and power boards are only a temporary answer to powering appliances and equipment; and
• Wear appropriate footwear - shoes and socks - when handling electrical equipment and appliances, particularly if the floor is wet.

ESV also put out a recent Guidance Note for electrical inspectors, dated December 2009, that covered a number of issues relating to electrical safety, including the replacement of existing switchboards, the main switch for solar installations, fixed wired air-conditioning installations, main switches for off-peak hot water services, standby generators and embedded networks.

Following are a few of the points outlined in the Guidance Note.

Replacement of existing switchboards

A switchboard containing semi-enclosed rewirable fuses may be replaced with a new circuit-breaker switchboard in the existing position under the following conditions:

1. The switchboard location complies with the regulations that were in force when the switchboard was first installed; and
2. No other electrical work is being carried out, eg, installation and/or rewiring of final sub-circuits or replacement of the consumers mains; and
3. The new switchboard complies with the safety switch (RCD) requirements stated in Clause of 2.6 and Amendment 1 of the 2007 edition of the Wiring Rules (AS/NZS 3000:2007).

Note that switchboards installed in cupboards must comply with Clause 2.9.2.5 of the Wiring Rules.

Solar installation main switch

An additional main switch for a solar installation can be installed on an existing switchboard if that switchboard complied with the electrical regulations that were in force when the switchboard was first installed.

The locking facility requirements for main switches now only applies to the solar main switch; however, it should be understood that this issue is still subject to further clarification by Standards Australia.

Requirements for fixed wired air-conditioning units

All fixed wired air-conditioning units shall be installed to comply with the following requirements:

1. They must have an isolating switch that is capable of being locked in the ‘off’ position, installed adjacent to or on the external compressor unit (an exception to this requirement is where an isolating switch that is capable of being locked in the ‘off’ position may be installed in a switchboard that is dedicated to the air-conditioning equipment only); and
2. Be installed as per the manufacturer’s installation instructions as required by Clause 1.7.1(c) of the 2007 Wiring Rules; and
3. Only cables enclosed in conduits are to be attached to the air-conditioning pipe work (note that the means of attachment must be permanently secured - use of PVC tape or plastic cable ties is not acceptable).

Main switch size calculation where there is an off-peak hot water service

When replacing a switchboard and the maximum demand of the installation exceeds the current carrying capacity of the consumer’s mains, a circuit breaker main switch (or switches) shall be installed to protect the consumer’s mains.

If the hot water service only operates off peak and does not have a boost element or changeover day rate switch, the hot water load can be discarded when calculating the circuit breaker main switch for the installation - subject to current tariff arrangements.

Standby generation - switching the neutral

If electing to switch a neutral conductor with associated active conductor, close attention is required to ensure compliance with the following:

1. The incoming neutral conductor before the MEN connection shall not be switched;
2. Neutral and earth conductors shall not be connected in parallel; and
3. The changeover device shall maintain the continuity of the neutral conductor (this means the neutral contacts make before the active contact when closing and open after the active contacts when opening - check manufacturerÂ’s certification).

Caution - some changeover units are designed with the neutral contacts having only a half or a third of the current-carrying capacity of the active contacts.

Embedded networks

An embedded network is a multiple installation (not a single installation), therefore the prescribed electrical installation extends to the sub-mains, earthing systems and any distribution board related to the control of each individual occupier’s portion of the multiple electrical installations.

Exception 3 of Clause 3.6.2 of Wiring Rules in relation to 7% voltage drop does not apply to this type of installation (maximum of 5% volt drop is only permitted).

Ceiling insulation electrical hazards

In recent months, the high incidence of deaths and house fires that are associated with the ‘stampede’ to cash in on government rebates for ceiling insulation installation has made headlines around the country and has cost at least one high-profile federal government minister his portfolio.

These tragedies mostly revolved around insulation installers using conductive fasteners with metallic foil insulation in close proximity to electrical circuits and carrying out their installations with little or no knowledge of the presence and/or dangers of the live electrical cabling that was in the ceilings around them. The dangers weren’t just present to them while installing the insulation. They also present dangers to both the home occupants who are put at risk of house fire and anyone who enters the ceiling space, including electricians, who are put at risk of unknowingly coming into contact with metallic insulation foil that is energised by an electrical circuit.

As an aside, it is interesting to note that there has been little or no mention of how safety switches may have saved people’s lives where breakers have tripped when installers have hit live electrical circuits during installation. The switches may also have prevented house fires when consumers turned on appliances connected to electrical circuits that were damaged by insulation installers. Given the high level of community awareness and public outcry about the electrical hazards caused by recent ceiling insulation installations, it is unfortunate that the value of safety switches did not come to the fore.

Representing the electrical contractor industry, NECA was very vocal in calling for the government to regulate the inspection of electrical systems before and after insulation installations were carried out to mitigate the risk of installer injury and house fires. It seems that this very good suggestion has been recognised and taken up by at least some of the state electrical regulators, some of whom have issued warnings and new instructions to both insulation installers and the electrical industry.

Notably, the Executive Director of the Electrical Safety Office in Queensland, Peter Lamont, issued a safety alert to licensed electrical workers on ceiling foil insulation risks on 11 March 2010, entitled ‘Conductive ceiling insulation and electrical safety - Insulation installers, licensed electrical contractors and licensed electrical workers’.

The Queensland electrical safety alert

The purpose of the safety alert is to remind insulation installers and licensed electricians about existing requirements relating to the management of ceiling insulation risks, and to provide details about new requirements regarding foil insulation which recently took effect.

The Minister for Industrial Relations has made a Ministerial Notice under the Electrical Safety Act 2002 effective from 9 March 2010 requiring installers to take additional precautions when installing electrically conductive ceiling insulation (other than metal foil batts) in premises where the insulation is applied onto the ceiling structure.

Insulation installers have been prohibited since 1 November 2009 from using conductive fastenings for foil ceiling insulation and are required to comply with the Wiring Rules (AS/NZS 3000: 2007) as they relate to the placement of any type of insulation near recessed downlights. Risk assessment training and documented risk assessments dealing with electrical safety risks are also required.

These requirements were mandated under the Electrical Safety (Installation of Ceiling Insulation) Notice 2009 and are now incorporated into a new Ministerial Notice, the Electrical Safety (Installation of Ceiling Insulation) Notice 2010 with the following additional provisions:

• An electrical safety inspection and test of the electrical installation related to the ceiling space at the premises must be performed by a licensed electrical contractor before electrically conductive ceiling insulation is installed; and
• Following the inspection and test, if any part of the electrical installation in the ceiling space is not electrically safe, the installation of electrically conductive ceiling insulation must not proceed until the installation is made safe or repaired.

If the outcome of the inspection and test of the electrical installation undertaken confirms that the electrical installation is electrically safe, then electrically conductive insulation may be installed under the following conditions:

• Before commencing the installation of electrically conductive ceiling insulation, a safety switch is installed on each final sub-circuit and sub-mains located in the ceiling space where such installation is possible; and
• The consumer’s mains and/or cables of the electrical installation not able to be protected by a safety switch are clearly identified and marked permanently at the most accessible point and at intervals not exceeding 1 m in the ceiling space to the extent that is reasonably practicable; and
• The electrically conductive ceiling insulation is installed so as to ensure that the consumer’s mains and any circuit not able to be protected by a safety switch are not covered at any point by the ceiling insulation; and
• During the installation, a minimum of 25 mm separation is maintained between the ceiling insulation material and the consumer’s mains and/or any cables of the electrical installation not able to be protected by a safety switch.

The Ministerial Notice applies in Queensland, irrespective of any requirements or conditions of the Australian government’s yet-to-commence Household Renewable Energy Bonus Scheme.

Thankfully, we’re seeing a proactive response from regulators to this serious safety risk to electrical and other trades. It’s reassuring, too, to see that safety switches are being mandated as an additional means to mitigate these risks. Hopefully, it’s just a matter of time before other state electrical and/or building authorities issue similar regulations to address the risks associated with foil-based ceiling insulation.