No explosions please:) class1, div. 2

[teleski]

I have a purged enclosure in a cl.1, div. 2 location. There is a 480v 3ph feed branching off to a control xfmr and several motor starters. The cabinet was designed that upon loss of purge, everything south of the secondary side of the xfmr is to drop out, removing the potential for the contactors to operate, but leaving the 480v feed intact. In my experience, the feed is usually brought to an external contactor. Upon loss of purge, all power to the enclosure is removed. not sure which direction to go with this...

 

[Grollor33]

I'm not sure I completely understand the scenario.

Are you unable to use a UPS?

 

[l3city]

Hi there!
This is the part I don't get..

"In my experience, the feed is usually brought to an external contactor. Upon loss of purge, all power to the enclosure is removed. not sure which direction to go with this..."

Can you be more specific? thx
Regards

 

[stephenw22]

I should preface this by saying I'm located in Canada, so rules in other countries may be different.

From what I understand from your description, that installation would be fine up here.

Terminal blocks, lugs, and other 'non-arcing and non-sparking' devices are allowed in Cl.1, Div.2. As long as power is cut to all unclassified bits and pieces, it's fine. Power can still enter the box and land on a terminal strip.

Transformers are typically considered safe for Cl.1, Div.2, and there are a few manufacturers that make potted transformers that are specifically Div.2 rated.

 

[resqcapt19]

Teleski,
It appears that you are using "Type Z" pressurizaition to change the inside of the elclosure from Class I, Divison 2 to nonhazardous. If so NFPA 496 only requires an alarm on loss of pressure. It does not require remote power shutdown as required for "Type X" pressurization (Class I, Div 1 to nonhazardous)
Don