Page 42 - Energize January 2022

VIEWS AND OPINION

Dangerous claims about flameproof junction boxes

for use in Zone 0 applications

By Dr Geoff Mood, CCG Cable Terminations

n the November issue of this Ex enclosure (usually Ex-e) and putting them inside an Ex-d enclosure with an IP rating of
publication the author of the article IP54 or better would satisfy this requirement. However, this does not make the level of
IThe Evolution of a cast iron flameproof protection provided by the Ex-e terminals independent of the Ex-d protection provided by
junction box, made a series of incorrect the enclosure as they depend directly upon the Ex-d enclosure for ingress protection and
and misleading statements. The author protection against impact in order for the terminals to achieve their Ex-e certification. The
also made a dangerously incorrect claim combination of any Ex-d enclosure with any Ex-e terminals will therefore only provide one
about the suitability of installing an Ex-d level of protection being EPL Gb, not the two independent levels of protection required for
flameproof enclosure with Ex-e terminals Zone 0 use as claimed by the author.
in a Zone 0 area. Those installers who If further proof is needed, the certification number of the authors own Ex-e terminals
believed the claims and installed the ends with the letter ‘U’. This means that these terminals are certified only as components
product accordingly would at the and therefore must be re-assessed as part of an Ex-assembly. To quote IEC 60079-0 “The
least be negligent of their obligations symbol “U” is used to identify that the equipment is incomplete and is not suitable for
for installing electrical equipment installation without further evaluation.” This is hardly the language used of a product
in hazardous areas and would most providing an independent level of protection and is in complete conflict with the authors
likely be criminally responsible for any advice. Unfortunately, the author of the article does not seem to know these quite
resulting explosion and loss of life. basic facts and compounded the earlier incorrect statements by adding the following
The claim was that by installing Ex-e dangerous statement: -
terminals inside an Ex-d junction box, the “The important part to remember, if you are advising anyone on such an installation,
installer would achieve the two levels of is that this termination is now suitable for Zone 0 applications, with minimal additional
independent Ex protection required for a consideration.”
Zone 0 installation. This erroneous claim My response to this is that if you are giving advice about a Zone 0 installations then you
is seductive and dangerously wrong. should really know the Ex-standards and what is required (and so should the person who
The actual wording of the claim specifies the installation). The specifier should also examine the certification of the products
made was “However, with the inclusion being used in such a safety-critical application.
of increased-safety terminals inside a SANS/IEC 60079-14 clause 4 states: “It is necessary to ensure that any installation
flameproof enclosure, the terminations complies with the relevant equipment certificate as well as with this standard and any
rating is pushed up to Zone 0 (two other requirements specific to the plant on which the installation takes place.”
independent levels of protection via EPL The authors words “with minimal additional consideration” sounds like a legal
Gb, per SANS/IEC 60079-14/26) meaning escape clause.
it can now be installed in an environment When it comes to installing electrical equipment in Zone-0 or in any zone for that matter,
where there is a constant hazardous there are many “additional considerations”
environment.” SANS 10086-1 clause 4.3.2.5.1 clearly states: “Power systems shall not be installed in
The important words to take note zone 0 areas.” However, the author dangerously advocates the use of a flameproof box as a
of are “two independent levels of power supply connection box within a Zone 0 area.
protection”. SANS /IEC 60079-14 Scope clearly states: “Where the equipment is required to meet
It seems that the author is not other environmental conditions, for example, protection against ingress of water and
familiar with the certification of resistance to corrosion, additional protection requirements may be necessary.”
his own company’s products. The In clause 4 the standard goes on to say, “Consideration should be given to obtaining
certification of any Ex-e terminal information for maintenance and repair to meet the requirements of IEC 60079-17 and IEC
(including the authors own terminals) 60079-19 respectively.” “- documentation relating to the suitability of the equipment for
always contain the following words in the area and environment to which it will be exposed, e.g., temperature ratings, type of
their Schedule of Limitation: - “The protection, IP rating, corrosion resistance.”
terminals may only be used inside a Clause 5.9 of the standard says, “Electrical equipment shall be selected and/or installed
previously approved Ex enclosure with so that it is protected against external influences which could adversely affect the explosion
a minimum IP rating of IP54.” protection.”’, and lists corrosion, chemicals, condensation and moisture as some of the
This means quite clearly that the external influences to consider.
terminals only become certified Ex-e to The specifier /installer must consider the effects of hazardous gasses or vapours on the
EPL Gb when they are inside a suitable integrity of the installation with regards to the performance of the flame path, the IP seals

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