Not exactly. The requirement is to be competent to do your work. And in Australia it is a mandatory requirement in most cases as it comes from AS/NZS 3000 – The Wiring Rules. There are some exemptions, but state law usually requires electrical installations to comply with this standard. Section 7.7 of the Wiring Rules talks about installations in hazardous areas, and says that they must comply with another standard – AS/NZS 60079.14, which thereby also becomes mandatory. And clause 4.4 of AS/NZS 60079.14 says that persons working with explosion protected electrical equipment (EEHA) in hazardous areas must be competent to do their work.
So how do you demonstrate that you are competent? Clause 4.4 nominates undertaking training and assessment to the EEHA Competency Standard, AS/NZS 4761.1, as one way of demonstrating competency. It is not the only way, but because it provides a very clear way of demonstrating that the requirement has been met, it has become the preferred method of demonstrating competency in many industries. All training and assessment offered by Extend Training meets AS/NZS 4761.1 (the competency unit codes we refer to on this site are taken from the national training package UEE11, but they are based on and equivalent to AS/NZS 4761.1).
See also, “Do I need to have a Cert IV in Hazardous Areas in order to work in hazardous areas?”
The main thing to consider when choosing your course is the type of work that you will be doing – look at the titles of the units of competency in the course and make sure they cover the tasks you will be performing. Generally, electrical and instrumentation technicians and other “hands-on” folks, will be best off with our EEHA Installation, Maintenance and Inspection (EEHAIMI) course, which covers the hands-on aspects of installing, maintaining and inspecting hazardous area equipment. Engineers and designers may be more interested in our Hazardous Area Electrical Design (HAD), or Hazardous Area Classification (HAC) courses, but if you are involved in inspection work then you may also benefit from completing the inspection competencies from the EEHAIMI course. If you need competencies from several courses please don’t hesitate to give us a call about putting a customised program together for you to reduce your training time and cost.
The Certificate IV in Hazardous Areas is a qualification from national training package UEE11 made up of some units of competency that are related to hazardous areas and others that are more general. The hazardous area units are based on AS/NZS 4761.1, and although there are different options, in completing the Cert IV most people will undertake units covering the common EEHA tasks of installation, maintenance and inspection. The Cert IV also contains a general, or “soft-skill” component, with units of competency relating to health and safety and report writing that have very little to do with hazardous areas.The list of core and elective units of competency for the Cert IV can be found here.
The short answer is no, not to meet the competency requirement of AS/NZS 60079.14, which is simply to be competent to do whatever task you are doing. So if the task is installation of explosion protected equipment, then you need to be competent in EEHA installation; if the task is inspection, you need to be competent to inspect, and so on. The EEHA competency standard, AS/NZS 4761.1, sets out units of competency related to specific tasks, e.g. “Install explosion-protected equipment and wiring systems,” and “Conduct detailed inspection of hazardous areas installations.” Since AS/NZS 4761 is mentioned in AS/NZS 60079.14 as one way of demonstrating competency, completing training and assessment to obtain the units relevant to your role is sufficient to satisfy the requirement.
However, some organisations do require employees to hold a Certificate IV in Hazardous Areas, in most cases because of an internal policy. Because there is additional study involved, there can be a perception that a person with a Cert IV in Hazardous Areas has more EEHA knowledge than a person holding only units of competency (which may be why some organisations request it), but because the “soft-skill” part of the qualification is not related to EEHA this is not necessarily accurate. We’d suggest checking with your employer or prospective employer what their requirements are before embarking on the Cert IV.
See also, “What is the Cert IV in Hazardous Areas?”
What are “thermoplastic, thermosetting or elastomeric insulated cables”?
Basically any cable insulated with a “plastic” or “rubberised” polymer material. Most cables in common industrial use (with the exception of MIMS – Mineral-Insulated Metal-Sheathed, paper-lead cables and a few others) are insulated and/or sheathed with materials that fall into one of the three categories.
- Thermoplastics are polymers that are soft and pliable at higher temperatures but solid when cooled. Their polymer chains separate when heated allowing them to be melted and remoulded time and again. PVC is a common thermoplastic insulator.
- Thermosetting plastics have a polymer structure that is cross-linked. Once cured, thermoset materials are irreversibly moulded. Unlike thermoplastics, they cannot be melted as they decompose and burn before their melting temperature is reached. XLPE (Cross-Linked Poly Ethylene) is a common thermoplastic insulator. Cross-linked materials usually have a higher temperature rating than thermoplastics.
- Elastomeric insulation is also known as “Rubber Insulation” and as the name suggests are natural or synthetic rubber materials. There are many kinds, including EPR (Ethylene Propylene Rubber), which is commonly used in offshore cables.
What is “cold flow”?Cable insulation used off shore is required to be low-smoke, zero halogen. This requirement was introduced after the Piper Alpha accident, where many of the victims were killed by the chlorine gas released by burning PVC cable insulation. Unfortunately, the materials used in place of PVC sometimes exhibit “cold flow” characteristics. AS/NZS 60079.14 describes cold flow as “the movement of the cable sheath under the compressive forces created by the displacement of seals”. Many cable gland seals can apply a compressive force that is greater than the resistance of the cable sheath to deformation. As we tighten the cable gland the insulation is squeezed under the seal and becomes thinner over time. Cold flow can give rise to a reduction in the insulation resistance of the cable, and may slowly reduce the effectiveness of the IP seal on the cable sheath. The only way to prevent this from happening is by selecting cable glands appropriate to the cable type, and by understanding how to correctly fit the gland according to the manufacturer’s instructions– overtightening seals must be avoided.
Can I use grease on fastening bolts and threaded entries into flameproof enclosures?
The short answer is yes, but what sort of grease? Substances we use on any mating surfaces of a flameproof enclosure must meet certain requirements:
- They cannot harden (we don’t want to permanently join the surfaces together thereby preventing the joints from acting as a flame path)
- They cannot be solvent based (if the base of the grease is a solvent, it will likely be flammable, which creates a problem, right?)
- They must be anti-corrosive ( no explanation necessary)
- They must maintain electrical continuity between surfaces (we don’t want different potentials between the gland and the enclosure etc.)
There are a number of greases available that meet the criteria:
- Silicone based greases (e.g. Dow Corning No. 4, some Molykote products) are usually suitable but can cause poisoning problems with gas detector sensors.
- Graphite type greases (non-solvent based, usually dark grey/black, sticky and messy)
- Lanolin type greases (e.g. Lanotec). These are non-solvent based, made from sheep’s wool.
- Synthetic greases such as Dow 802, most of which are silicone based.
By all means use grease, but don’t slather it on, use it sparingly. Make sure surfaces are clean before applying and don’t dip bolts into the grease and then screw into blind holes, which may create a “hydraulic lock” at the bottom of the hole and prevent the bolt from seating properly.
Can I use thread tape on my cable entries into flameproof equipment?Short answer, No. The effect of tape on threads would be to seal any tolerance between the male and female mating threads, effectively sealing the threaded flame path. It may be argued that that putting an IP washer on the gland (which is permitted) is effectively doing the same thing (sealing the cable entry flame path), but an IP washer is external to the flamepath – it does not sit between the threads, so does not cause the same issue. The enclosure would not have been tested with thread tape on threaded flamepaths and it is difficult to predict what effect it might have in the event of an internal explosion. Thread tape may also compromise earth continuity between the gland and body.
Can I add an extra label to certified Ex equipment and if so, how?Yes, but, the act of fixing the extra label must not affect the explosion protection afforded by the technique.
There are a couple of things to be aware of:
- Drilling holes into the enclosures to mount the label is generally not permitted. (IP rating and impact rating may be compromised)
- Any adhesives used must be compatible with the enclosure material. Impact rating may be compromised by degradation of resins in the enclosure material. (for GRP type enlcosures)
- Be aware of static charges, especially for large non-conductive labels (AS/NZS 60079.0 sets limits on the surface area of non-conductive materials for hazardous area equipment.)
Refer to Clause 4.3.1 of AS/NZS 60079.17.
How much damage is too much on an Ex d enclosure?This is a difficult question as there is really no definitive answer. The only reference to any sort of scratch/roughness measurement is the Maximum Surface Roughness requirement in AS/NZS 60079.1, which states roughness must be less than 6.3µm. This is an equipment design requirement, not a repair or maintenance requirement but it is the only value given in the standards. The requirements for repair of Ex d equipment in AS/NZS 3800 do not provide guidance on damage to flamepaths, other than stating they must be machined before any corrosion or scratch takes the enclosure past acceptable tolerance limits. Some people use Figure F2 in AS/NZS3800 for guidance, however this graph is only for Group I equipment. As a rule of thumb, if the scratch can be felt with your fingernail it is probably too deep (>6.3µm) and will require machining or replacing the equipment.
I have been told that the conductors are not allowed to touch each other or the side of the sleeve in a compound gland. Is this true?No. It is almost impossible to separate the conductors so that they don’t touch as they pass through the compound and the sleeve. It may be possible with a 2 or 3 core or even a 4 core cable but quickly becomes impossible when dealing with multi-pair instrument cables. As long as the filling compound seals between the cores at the base of the gland where the crutch of the cable is and the sleeve is full of compound, all is good. And it really doesn’t matter if the compound at the top of the sleeve has a slight dome or is flat, as long as the sleeve is filled as per the manufacturer’s instructions.