ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
Calling all Non-US members!! (Non-US only)
by Bill Addiss. 08/13/18 05:52 PM
Upgrade the old panel
by gfretwell. 08/13/18 12:20 AM
depth of duckbank
by ghost307. 08/12/18 09:26 PM
Section 179 vehicle purchases
by BigB. 08/05/18 01:06 PM
Don't you buy this stuff
by BigB. 08/05/18 01:00 PM
New in the Gallery:
Plug terminals
Housebilding DIY wiring
Who's Online Now
0 registered members (), 5 guests, and 24 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
UPS cabling & shared raceways #162439
04/19/07 09:58 AM
04/19/07 09:58 AM
S
SteveFehr  Offline OP
Member
Joined: Mar 2005
Posts: 1,213
Chesapeake, VA
I inspected a UPS installation yesterday we and filled up 2 sheets of violations. One of which had to do with the conduit; the electrician had installed the UPS rectifier input, bypass input and output cabling in a single 4" piece of rigid conduit. They had also run the UPS alarm cabling through the same conduit. My colleage and I are both certain it's illegal, but couldn't recall exactly WHY- the two inputs (rectifier and bypass) are fed from different transformers, but coming from a common bus. Is it legal to put both of those in a single raceway? Is it legal to put the UPS output cabling in the same raceway as that?

And finally, the data cable they used has no markings on it to indicate voltage rating or that it's class 2 so it's illegal in this case- if it WAS 600V class 2, would it be legal to run it in the same conduit? It's not controlling the UPS, but is taking alarm signals from the UPS ("on bypass") to the wraparound maintenance bypass switch.

2017 / 2014 NEC & Related Books and Study Guides
Re: UPS cabling & shared raceways [Re: SteveFehr] #162443
04/19/07 10:17 AM
04/19/07 10:17 AM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,251
Estero,Fl,usa
The only way this low voltage signalling circuit can be in the same pipe is if it meets the requirements of a class 1 (basically using the same wiring methods as chapter 3). The other requirement is that it is associated with the power circuits it shares a raceway with, but you have that.


Greg Fretwell
Re: UPS cabling & shared raceways [Re: gfretwell] #162547
04/20/07 09:07 PM
04/20/07 09:07 PM
M
mhulbert  Offline
Member
Joined: Oct 2004
Posts: 132
Anaheim, CA USA
As far as running the input, bypass, and output in the same conduit...wouldn't these be Separately Derived Systems? You can run power wires of different systems and voltages in the same raceway. I don't see a code problem with it, though it is a bad design as far as uptime goes.
Mike

Re: UPS cabling & shared raceways [Re: mhulbert] #162685
04/23/07 07:20 PM
04/23/07 07:20 PM
S
SteveFehr  Offline OP
Member
Joined: Mar 2005
Posts: 1,213
Chesapeake, VA
They've got bad practice all over this job, that's for sure! I can't reject this shared conduit unless there's an actual code violation, though. Ah well, I guess I'll be hitting the NEC hard tomorrow morning...

Re: UPS cabling & shared raceways [Re: SteveFehr] #162688
04/23/07 08:37 PM
04/23/07 08:37 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,251
Estero,Fl,usa
725 is the most confusing part of the NEC IMHO.
The different interpretions I have seen are even more confusing than the language of the code.


Greg Fretwell
Re: UPS cabling & shared raceways [Re: gfretwell] #162705
04/24/07 07:08 AM
04/24/07 07:08 AM
S
SteveFehr  Offline OP
Member
Joined: Mar 2005
Posts: 1,213
Chesapeake, VA
The UPS manual says the alarm & signaling circuits are Class 1, and should be installed IAW NEC Class 1 requirements. NEC 725.26(A) Permits Class 1 circuits to share a cableway with power cables, but only if it's rated for the highest voltage in the raceway. The cabling installed on-site gave no indication of any voltage rating.

Also, the power cabling they installed was labeled "TW75" What the heck is TW75, Canadian THW?

NEC 250.20(D) FPN No.1 notes that on-site generators are not considered separately derived if the neutral is solidly interconnected to the service-supplied neutral. As this is the case with this UPS, I do not believe it would be considered separately derived.

Last edited by SteveFehr; 04/24/07 07:17 AM.
Re: UPS cabling & shared raceways [Re: SteveFehr] #162717
04/24/07 11:51 AM
04/24/07 11:51 AM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,251
Estero,Fl,usa
I guess you ae left with the question of the rating of your LV cable. The general rule with inspectors is, if it isn't labelled it does not have a voltage rating.


Greg Fretwell

Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Niko
Niko
Campbell, CA
Posts: 356
Joined: August 2006
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
248,506 Are you busy
186,194 Re: Forum
175,656 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.022s Queries: 15 (0.004s) Memory: 0.9865 MB (Peak: 1.1420 MB) Zlib enabled. Server Time: 2018-08-14 08:26:45 UTC