Outlets - suspended ceiling

[Chukster]

When I said it was often a plenum, I was referring to commercial, which is the world I work/live in. In residential, you have to assess whether it is or isn't. but in commercial, you can pretty much assume it is and be right 95% of the time.

Having worked in two-way radio and coaxial cables, there are lots of installations out there where black-plastic jacketed non-plenum cable has been pulled thru plenum ceilings. Instead of the powder-blue plenum rated $$$$
stuff. Yeah.

Also, I did have to urge a 911 center person to have a FD stop using 120VAC on zip-cord thru the ceiling from the desk radio & siren relay to the HV contactor on the siren. MMM, I didn't relish any idea of being asked if I knew about it, even if I didn't install it.

 

[alfredeneuman]

but in commercial, you can pretty much assume it is and be right 95% of the time.

I spent 45 years in commercial electrical and encountered a ceiling used as an air return maybe 4 or 5 times.

 

[n8n]

I spent 45 years in commercial electrical and encountered a ceiling used as an air return maybe 4 or 5 times.

I dunno what to tell you... I do fire alarm designs so as a result I need to know where all of the HVAC returns are (so they get detection for AHU shut down) and most of the new construction work I do is high rise office buildings. I can't remember the last time I saw a ducted return - that seems to be only used in Group R occupancies.

 

[alfredeneuman]

But 95% ?
Most of my work was in concrete tilt up builds w/offices that had grid ceilings.
Very few high rises. (there aren't many high rises across the US) I didn't do much in the way of Type R (residential).
The places I did see w/ plenum returns were huge shopping malls.

 

[wyliesdiesels]

we have one building here in town that i know of with plenum return ceiling. its a high rise medical building so with central chillers...

 

[n8n]

But 95% ?
Most of my work was in concrete tilt up builds w/offices that had grid ceilings.
Very few high rises. (there aren't many high rises across the US) I didn't do much in the way of Type R (residential).
The places I did see w/ plenum returns were huge shopping malls.

Well I do work in the metro DC area, and primarily work on high rises (that's all anyone is actually constructing new these days in my area) so yeah, from my perspective yes.

Good to be reminded every now and then that this is not the norm everywhere.