The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
230 or 345 kV transmission lines?
by Vlado
09/24/16 09:33 AM
breaker meltdown
by crselectric
09/24/16 12:42 AM
Electrical mast flashing product
by ThomasWinfrey
09/22/16 12:14 AM
What estimating software do you recommend?
by sparky
09/21/16 07:20 PM
"Dry Run" Inspection goes awry
by HotLine1
09/20/16 07:39 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
HotLine1 14
sparky 9
sparky66wv 8
gfretwell 8
Vlado 6
Who's Online
0 registered (), 99 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#193490 - 04/05/10 06:15 AM transformer above ceiling?
cgw Offline
Member

Registered: 07/29/04
Posts: 133
Loc: Rochester NY
30KVA dry type transformer (480 X 120/208)
Can it be located above a suspended accessible ceiling (say in a medical office building)?
Can it be located above this ceiling if the ceiling space is a return air plenum?

Top
2014 / 2011 NEC & Related Books and Study Guides
#193502 - 04/05/10 04:10 PM Re: transformer above ceiling? [Re: cgw]
Gregtaylor Offline
Member

Registered: 03/02/05
Posts: 212
Loc: Boise, Idaho, USA
NEC 2008 450.13(B) says, generally for this size and type, you can. The plenum space question is not addressed.

Top
#193506 - 04/05/10 06:40 PM Re: transformer above ceiling? [Re: Gregtaylor]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6785
Loc: Brick, NJ USA
300.22 (c)(2) should be read, and then I suggest you speak to the local AHJ for his/her interp. Under 50 KVA is no issue, BUT...the air handling ceiling needs to be addressed. Also, you may want to have a cut sheet for the exact xfr you intend to install.
_________________________
John

Top
#193508 - 04/05/10 07:52 PM Re: transformer above ceiling? [Re: HotLine1]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9012
Loc: Estero,Fl,usa
I think this is probably legal, depending on the transformer but it might be a questionable design choice. If that transformer smokes it will share the joy with the rest of the building pretty fast, at least that HVAC zone anyway.
_________________________
Greg Fretwell

Top
#193588 - 04/08/10 05:07 PM Re: transformer above ceiling? [Re: gfretwell]
Tesla Offline
Member

Registered: 06/16/04
Posts: 1280
Loc: Sacramento, CA
If the Life Safety System ( Fire Alarm ) is up to snuff a duct detector is going to shut things down well enough in time.

Not quite the same set-up...

But I rigged a 45kVA XFRMR, dry-type, above a grid to give isolated power to data loads. Upon the detection of fire, within this space only, a shunt-trip killed total power - with a time delay of seconds so that the data state could be frozen/ preserved. Subsequently the dry fire system would be flooded into the now unpowered space.

So the question of plenum return air really would seem to be a life safety question not to be answered within our Code.
_________________________
Tesla

Top



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals