Electrical testing standards

Workplace safety is a serious concern for all employees and employers. In the electrical industry, it's not limited to installation practices and tools. Testing is a high-risk activity that can be done safely by following the standards and regulations.

Electrical testing is addressed by legislation, regulations and mandatory and reference standards. While it's difficult to keep up with it all, you can't be ignorant about this important topic that's a daily activity for many electricians. To help out, I spoke with some experts to get their valuable guidance on testing - John Piperides, Fluke program manager for DMMs and member of EL001-21 standards committee who produced AS3017 and Nuri Chorvat, principal electrical engineer at Newcrest Mining's Telfer gold mine and chairman of standards committee EL-049 'Safety of electrical equipment for measurement, control and laboratory use'.

What happens when the wrong electrical tester is used?

Piperides: I've seen serious burns, catastrophic system failures and destroyed DMMs because testers were incorrectly selected or incorrectly used on electrical circuits. It's important for contractors to know the tester criteria required for specific applications before they work on them.

What's the hierarchy between the Wiring Rules and tester standards?

Piperides: AS3000 is the primary standard electricians focus on, since it's mandated for all electrical installations. When the revised version is released later this year, there will be some changes to testing, but contractors need to realise that it refers to many other standards on testing.

The important fixed-installation testing standards are AS3017, AS61010 and HB187. AS3017, currently in provisional draft form and expected late 2007, covers things like loop impedance, polarity, RCDs and earth resistance; and is a recommended standard, as are AS61010 on tester safety and HB187 - the handbook on selecting a safe tester.

For portable appliance tests, AS3760 is an important standard to test appliances that are portable. This is emphasised by the increased attention Workcover gives to this issue. Workcover NSW for example, has released the 'Low voltage electrical work code of practice', to help people working on portable appliances better understand the OHS Act:2000 and the OHS Regulation:2001 that deal with this matter.

What relevance does Workcover legislation have to electrical testing?

Piperides: The whole area of electrical safety is being extensively analysed by state-based Workcover Safety government agencies, with a view to increasing safety standards for the obvious human safety benefits, but also to deal with litigious issues. There are several cases in the public domain, such as the NSW Coroner's reports, that highlight the unacceptable incidence of electrical-related deaths and injuries and the litigation taken against companies and individuals involved.

How are standards linked to the OHS Act and Regulations?

Piperides: Testing standards are overarching references for testing to make sure an appliance is safe. The Act and Regulation are enforceable when the test needs to be done.

Contractors should note that there are tighter electrical regulations for construction sites because the risk of injury is higher - electrically operated tools like rotary hammers and grinders are often used in harsh environments where the cords are dragged across rough surfaces or run over, and therefore present a risk of injury to not only the user, but to other tradespeople working in the vicinity as well.

What do you recommend contractors do about testing standards and the regulations associated with them?

Piperides: Contractors should get familiar with the OHS Acts and Regulations in their state to ensure they're both legally and technically safe. For example, Section 7.3 of the NSW OHS code of practice says: "All plant, including portable electrical equipment and flexible cords, must be visually inspected and tested to clauses 64 and 65 of the OHS Regulations and AS3760".

What was the rationale behind producing HB187-2006?

Chorvat: HB187 provides guidance on selecting a safe multimeter that complies with AS 61010.1. It was prepared by the technical committee following our concerns over the lack of public and industry awareness of the standard and a poor understanding of safety specifications when purchasing electrical test and measuring equipment such as DMMs, clamp meters, oscilloscopes and insulation testers.

The guide's objective is to give all users a basic understanding of the important safety criteria specified in AS61010. The Australian electrical market provides a wide variety of test and measuring equipment that has been designed and manufactured to many differing safety specifications, with a broad range in price and quality. This can be very confusing for users. Users need to consider how important a well-designed and manufactured meter is for their safety, how to tell if a meter is safe for the intended use and how important verification testing by an independent laboratory is.

How should contractors get the most out of HB187?

Chorvat: I strongly encourage all electrical personnel, including apprentices, to read this handbook and discuss the safety issues involved at their safety meetings and use it to select safe meters for their applications.

Who else should become familiar with HB187?

Chorvat: People who sell and rent out electrical test and measurement equipment also need to be familiar with HB187. In particular, they need to understand what measurement categories and voltage ratings mean, because these two parameters largely determine what tester should be used for a specific situation. I believe tester distributors should provide copies of HB187 to their sales staff so that they can provide their customers - electrical contractors - with technically accurate information to enable them to make an informed selection of the right testers for their specific applications. I also recommend that all sales outlets offering this equipment place a printed copy of HB187 in public view next to the equipment so customers can read it for themselves.

What's the significance of measurement categories and voltage ratings?

Chorvat: Measurement categories indicate the ability of the meter to safely withstand the prospective fault energy available in the circuit being tested. The higher the circuit energy, the higher the category of tester required, so the higher the tester's category rating, the safer the meter. However, you need to have a rough idea of the prospective fault current available at the point of testing, usually expressed in kA. As a guide, typical kA levels are: CAT I for very low-energy circuits, typically battery-powered, not connected to 240 VAC; CAT II for low-energy circuits like domestic use up to 5 kA fault currents; CAT III for medium-energy circuits like industrial and commercial use up to 25 kA fault currents; and CAT IV for high-energy circuits like industrial and commercial use over 25 kA fault currents.

Standard voltages in AS61010.1 are 50, 100, 150, 300, 600 and 1000. For multimeters sold in Australia, generally 300, 600 or 1000 V meters will suffice. AS61010.1 also applies to test leads, including current clamps, which should be certified to a category and voltage as high, or higher, than the meter they are used with.

Electrical testing standards

AS/NZS1660.3:1998	Test methods for electric cables, cords and conductors - Electrical tests
AS/NZS3017:2001	Electrical installations - Testing and inspection guidelines
AS/NZS3100:2002	Approval and test specification - General requirements for electrical equipment
AS/NZS3760:2003	In-service safety inspection and testing of electrical equipment
AS/NZS3820:1998 + Amdt 1:2004	Essential safety requirements for low voltage electrical equipment
AS61010:2004	Safety requirements for electrical equipment for measurement, control and laboratory use
HB187-2006	Guide to Selecting a Safe Multimeter