What type Junction Box to spec for EExd instrument?


Thread Starter


Rotork actuator having CENELEC classification EEx ed. I wish to deliver the control signals to the electrical housing via an intermediate field
junction box from a NON-intrinsically safe marshalling cabinet in the safe area.
The field area is Zone 1.
Can I install a field junction box that is classified as EEXe?, or am I required to have a EExd junction box?
The cable gland at the Rotork is EExed dual certified.
Firstly, protection type "ed" refers to "e" as in increased safety and "d" as in flameproof enclosure. Zone 1 refers to intermittent hazard.
This depends on which actual area you are working at. Also, please note the APPARATUS GROUP which is (or are) present in your area. IIC refers to Acetylene, IIB for Hydrogen, and so on. You need to install a EEx ed type of enclosure if there is a possibility of external explosion caused by some chemicals or elements I mentioned above plus the fact that there will be high temperature, or an occurrence of arcs and sparks in the area. It will still all depend to your analysis if you really need it. If there is no possibility of an explosion and (trapped)pressure, you can use EEx e type in a Zone 1 environment.

Bob Peterson

Presumably since you refer to intrinsically safe cabinet there are IS barriers somewhere, but no where do you mention that the thing is certified
for IS use (this would be EEXia, IIRC).

EEXd is roughly equivalent to NEMA 7 explosion proof (although not entirely), and would not require IS barriers.

So I am a bit confused about what you are up to.

Bob Peterson

David Bergeron, P.E.

According to ISA standard S12.1-1991 Table 3 (Summary of International protection techniques), "Ex e" (Increased safety protection) is allowed in Zone 1 areas. Paragraph 5.5.6 goes on to say that using "Ex e" protection in Zone 1 areas has been a controversial subject in Europe but the official classification allows it.

David Bergeron, P.E.
Thompson Equipment Co.
125 Industrial Ave
New Orleans, LA 70121
http://www.thompson-equipment.comPhone: 504-833-6381
Fax: 504-831-4664

There are no IS Circuits in the Safe Area Marshalling Cabinet.

Rotork will be about 200m from Safe Area. Intermediate Junction Box will be approx 30m from the Rotork

Hazardous Area is Zone 1.

Many thanks both you, TING & DAVID