UL508A - Distance ventilation openings

[Uze]

Hi everyone,

I would like to use ventilation for my electrical cabinet. When I read UL508A point 22.1 "Ventilation Openings," I see that I need to have at least 305 mm between the opening and a "possible source of arcing."


My First question: The ventilation manufacturer told me that the filter is UL94 5VA. Does this mean I don’t need an additional barrier? Is that correct? In UL 508A, I don’t see anything about this.


Second question: What should I consider a "possible source of arcing"? Does this include all of my power circuits?

Thank you in advance for your reply

"22.1 Unless a ventilation opening is located at least 12 inches (305 mm) from an arcing part, a barrier of metal or of a material such as those specified in 22.4 shall be interposed between the ventilation opening and a possible source of arcing, such as a power-circuit disconnect switch, the vent openings of a circuit breaker, a contactor, or an overload relay."

 

[Dennis Alwon]

I am sure someone will be able to help but if not there is this long free recorded webinar on UL508A. I don't even know if it will help

https://ultraining.myabsorb.com/#/online-courses/40422f64-5bec-48ef-ab5f-42476311f5aa

 

[jim dungar]

Does this include all of my power circuits?

It includes those power devices which open/break/interrupt current using contacts exposed to air. Think of all air break switches.
It would not include sealed or non-air break devices like solid state components or those sealed like fuses.

 

[Uze]

Thank you for your responses.
Have you already received feedback the ventilation filters can be considered as a barrier?