ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
turning down possible problem customer
by HotLine1. 05/21/18 07:53 AM
480 Delta
by sparkyinak. 05/20/18 09:33 PM
Furnace igniter leaking noise to stereo
by sparkyinak. 05/20/18 07:20 PM
electircal ageing test on IPC
by HotLine1. 05/14/18 09:42 AM
What estimating software do you recommend?
by wattsittoyou. 05/14/18 06:28 AM
New in the Gallery:
Plug terminals
Housebilding DIY wiring
Who's Online Now
2 registered members (Tjia1981, ghost307), 9 guests, and 11 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
480v lighting #170916
11/14/07 11:09 PM
11/14/07 11:09 PM
E
etech  Offline OP
Member
Joined: Jun 2007
Posts: 17
Oregon
14 pole lights draw 14 amps at 480v single phase.
Clamp on meter reads 14 amps on one leg, 12 amps on the other leg. The other group of 12 pole lights draw 12 amps on both legs. Am I wrong to think that both legs should read the same. All comments are welcome
Thanks.

Work Gear for Electricians and the Trades
Re: 480v lighting [Re: etech] #170923
11/15/07 03:01 AM
11/15/07 03:01 AM
Scott35  Offline

Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA
Good question!

Is the CT of the Ammeter too close to the Ballast's Core, resulting in an incorrect reading?

Additionally, could the Branch Circuitry be Multiwire with a common Grounded Conductor?

Additionally, could the unbalanced fixture's ballast be leaking some current to the equipment grounding conductor? (like a grounded segment at the Reactor Coil, or an uncapped AutoTransformer Multivoltage Tap lead connecting to grounded metal equipment)

Maybe someone has tapped into that 14 amp line, and made an L-G connection somewhere - causing the unusual imbalance.

Scott


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Re: 480v lighting [Re: Scott35] #170930
11/15/07 11:57 AM
11/15/07 11:57 AM
Z
Zapped  Offline
Member
Joined: Oct 2002
Posts: 482
Huntington Beach, CA, USA
Yes, ballasted loads do strange things when hooked up to meters (take a look at a spectrum analyser and a sine wave graph on a multi ballasted circuit some time - ugly business). Double check your readings, then ask yourself a few questions...

Is there a problem with the lighting performance? (i.e. a slow starting ballast, cycling or super bright lamp, etc.)

Which reading (12A or 14A) matches the expected draw of the lighting?

If you take a few fixtures off the circuit, do the legs level out?

My guess is that you'll find one or more of the fixtures to be your culprit(s). Once narrowed down, a ballast change out (or two) may be in order. Either that, or the wiring to/from a particular fixture is the answer.

Good Luck!


Featured:

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

 

Member Spotlight
richard
richard
L.I. New York
Posts: 95
Joined: August 2003
Show All Member Profiles 
Top Posters(30 Days)
twh 12
Popular Topics(Views)
246,851 Are you busy
184,206 Re: Forum
173,447 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.031s Queries: 15 (0.006s) Memory: 0.9517 MB (Peak: 1.0756 MB) Zlib enabled. Server Time: 2018-05-21 13:05:42 UTC