We have procured a Customized PLC ExD Enclosure. Our vendor procured the Empty ExD enclosure from a certified Manufacturer, which based on the Schematics given to him by my vendor, drilled the required holes for cables, and mounted panel door switches and lights, and certified the enclosure with required Temperature Class based on the Heat dissipation. However under agreement between the 2 parties the installation of the PLC and internal components was done by my vendor and not the Exd enclosure manufacturer. Probably there was no inspection carried out by the ExD Enclosure Manufacturer.

The question is does this Enclosure required to be re-certified by UL/ATEX or it is not required?

 

Check the certificate number of the enclosure as supplied. If it has a suffix -U, this indicates that it is certified as a "component" and the finished box, with contents installed, must be re-certified as as a unit.

Even if the power dissipation etc of the installed equipment is correct, the internal arrangement of the components can cause "pressure piling" in the event of an internal ignition. This can result in the flammable mixture being forced into a separate part of the enclosure with its pressure increased prior to ignition. The effect of the pressure rise is to increase the maximum pressure reached in the event of an internal explosion, which is uncontrolled and may result in failure of the containment.

Usually, the party responsible for the final installation of the equipment in the panel is ultimately responsible for re-certifying the equipment in its final state.

 

I have checked but the certificate does not have the the suffix U. The suffix number is 06 ATEX 050.

> Check the certificate number of the enclosure as supplied. If it has a suffix -U, this indicates that it is
> certified as a "component" and the finished box, with contents installed, must be re-certified as as a unit.

 

if any changes has been done in Ex-D enclosure, new holes are drilled or any components installed. re-certification is required as Ex-D certificate is invalid.

> I have checked but the certificate does not have the the suffix U. The suffix number is 06 ATEX 050.

>> Check the certificate number of the enclosure as supplied. If it has a suffix -U, this indicates that it is
>> certified as a "component" and the finished box, with contents installed, must be re-certified as as a unit.