Yes a spray booth using flammable liquids and solvents installed in Victoria is prescribed works and does require a sign off by an H-Class Inspector.
Before we start with the details, I think it is first worth defining the requirements for prescribed works under the Electricity Safety (General) Regulations 2019 Version No. 001. We have provided relevant extracts from the document:
“Division 11—Inspection of electrical installation work
249 Electrical installation work that must be inspected
(1) For the purposes of section 45 of the Act, prescribed electrical installation work means work on all or part of any of the following electrical installations if they are ordinarily operated at low voltage or a voltage exceeding low voltage”
The following is the line that specifically deals with hazardous areas:
“(h) electrical equipment installed in a hazardous area and electrical equipment associated with the protection of a hazardous area but not installed within the hazardous area;”
The following is the line that’s identifies works that are excluded from the definition of prescribed works:
“(4) For the purposes of section 45 of the Act, prescribed electrical installation work does not include—
(a) the repair or maintenance of a single component part of an electrical installation; or
(b) the replacement of a single component part of an electrical installation by an equivalent component part at the same location; or
(c) the installation or connection of a consumer billing meter.”
Based on the information above a number of parameters need to be met in order to determine if the installation of a new spray booth that has been classified as a hazardous area is prescribed works. For this to be the case, 2 key questions need to be asked.
- Has work been carried out on all, or part of the new spray booth that is ordinarily operated at low voltage or a voltage exceeding low voltage? and,
- Is that LV electrical equipment installed in a hazardous area, or is that electrical equipment associated with the protection of a hazardous area but not installed within it?
It is clear that if the answer to these 2 questions is yes then the works are prescribed. To build further on this point we would like to demonstrate why the answer to these questions is yes in the vast majority of cases when applied to the installation of a new spray booth that has been classified as a hazardous area.
To the first question, has work been carried out on all or part of the new spray booth that is ordinarily operated at low voltage (LV) or a voltage exceeding low voltage (ELV)? The answer to this question can be assessed very quickly by determining the supply voltage to the booth and quickly assessing the key safety equipment associated with the booth, including the fan motors, interlocking systems, overload protection and the like. I have inspected a great many spray booths and to date I have not come across one that operates entirely at or below low voltages.
To the second question and the one that requires further inquiry, is the LV electrical equipment installed in a hazardous area, or is that electrical equipment associated with the protection of a hazardous area but not installed within the hazardous area? This question needs to be approached for 2 separate installation conditions:
- Spray booths that contain hazardous area certified LV equipment within the hazardous area,
- Spray booths that contain LV equipment associated with the protection of a hazardous area but not installed within the hazardous area.
The first scenarios is clearly prescribed works and we don’t think requires any further explanation, the second scenario is the one that in my opinion has been misunderstood so for the rest of this letter I shall set out to clarify these requirements and explain why these works are prescribed. I shall do this by addressing key areas listed in the subheadings below:
Protective Earthing: A hazardous area spray booth must meet all of the relevant protective earthing requirements for AS/NZS 3000 and AS/NZS 60079.14. One key function of this portative earthing is to mitigate voltage differences appearing between exposed conductive parts of equipment and extraneous conductive parts through equipotential bonding arrangements. The risk of voltage differences is heightened in a hazardous area and for this reason AS/NZS 60079.14 places more onerous requirements on equipotential bonding system. AS/NZS 60079.14 requires that for TN-C-S systems, all exposed and extraneous conductive parts are connected to the equipotential bonding system. This means that metal and conductive parts of the spray booth will need to be bonded to the earthing system if there exits the chance, in normal operation or fault conditions, of a voltage being displaced on them.
Dilution: Hazardous area protection techniques can be divided into 5 main methods. The different methods of protection can be summarized as follows:
(a) Exclusion: This method involves the exclusion of the hazardous material, either gas or dust, from the apparatus so that a spark or hot surface inside the apparatus cannot cause ignition. This is achieved by sealing the apparatus enclosure, by the use of enclosed devices or by filling the apparatus with some substance, which may be solid, liquid or inert gas.
(b) Explosion containment: This method aims to contain an explosion, if it does occur, in the apparatus. A flameproof enclosure is probably the best known and most widely used of all techniques, but it is only appropriate for gas hazards.
(c) Energy limitation: This method uses energy limitation. Flammable gases and combustible dusts have minimum ignition energies, below which it is not possible for an arc or spark to cause an explosion. If the energy in an electrical circuit can be maintained below these levels it cannot cause an explosion. Intrinsic safety is the most common technique used to achieve this.
(d) Dilution: This method involves dilution of a hazardous gas atmosphere below the LEL by ventilation. It is not appropriate for combustible dust areas.
(e) Avoidance of ignition source: This method aims to prevent an ignition source from occurring. The most common technique is increased safety. This is used for apparatus or parts of apparatus, such as terminal boxes, that do not arc or spark in normal service
It is the method of dilution that forms the primary protection of the hazardous area in a spray booth. The electrical safety systems called up in AS/NZS 4114 have a direct impact on the protection of the hazardous area by requiring fans to drive airflow as well as safety interlocks, pre purge and post purge cycles. The protective functions of these electrical systems can be validated by asking the following question. Could a compliance failure of the low voltage electrical systems associated with the spray booth reduce or eliminate the protection of the hazardous area? The answer is undoubtedly yes. A supplementary question should then be asked. Could a compliance failure of the low voltage electrical systems associated with the spray booth place persons, livestock or property at risk from fire and physical injury hazards that may arise as a result of those electrical failures. Once again, the answer is undeniably yes. It must be repeated that ventilation and dilution is a hazardous area protection method, if the readers of this document are in any doubt, I would direct them to AS 1482 Protection by ventilation Ex ‘v’ as the newer AS/NZS 60079-13 as a further confirmation that ventilation and dilution are protection methods for a hazardous areas.
Lithium Oil and Gas are of the firm belief that hazardous area spray booths with LV ventilation and control systems would be considered prescribed works under the Electricity Safety (General) Regulations 2019 Version No. 001 even if the LV equipment is not directly installed in the hazardous area because the LV equipment is associated with the protection of a hazardous area.
“This following information represents and opinion only of a general nature, the specifics of each individual situation must be taken into account with reference to the relevant Legislation, Codes of practice and Australian standards. Professional advice should be sort if there is any doubt.”