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

ECN Shout Chat
Top Posters(30 Days)
Admin 17
Recent Posts
Old decora style outlets
by Admin. 03/25/17 11:40 AM
ESA Arc flash course
by TheShockDoctors. 03/24/17 10:15 AM
fuse rejectors
by HotLine1. 03/24/17 07:53 AM
Another Forum Update
by Admin. 03/22/17 03:04 PM
Dining room plugs
by watersparkfalls. 03/21/17 10:31 PM
New in the Gallery:
SE cable question
Popular Topics(Views)
231,464 Are you busy
166,170 Re: Forum
160,628 Need opinion
Who's Online Now
0 registered members (), 52 guests, and 9 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#205541 - 03/02/12 05:12 PM 480 v hps lighting circuit  
Cinner  Offline
Member
Joined: Dec 2004
Posts: 78
Kelowna, B.C., Canada
I was working on a 480v hps lighting circuit and went to turn the circuit off to change the fixture but still measured 66 volts to ground on each leg. Does. Any one know why this would be?


Work Gear for Electricians and the Trades

#205542 - 03/02/12 06:15 PM Re: 480 v hps lighting circuit [Re: Cinner]  
LarryC  Offline
Member
Joined: Jul 2004
Posts: 781
Winchester, NH, US
What type of meter did you measure the voltage with? If it is an electronic meter with the high input impeadence, it will measure "ghost" voltages. These "ghost" voltages are due to the wires traveling next to energized wires. Both set of wires are acting as a transformer.

Measure the voltage with a Wiggy or equivalent and the voltage will PROBABLY disappear. If they do not disappear, you have a problem. If the voltage does disappear then you are measuring ghost voltages.


#205543 - 03/02/12 06:22 PM Re: 480 v hps lighting circuit [Re: Cinner]  
Cinner  Offline
Member
Joined: Dec 2004
Posts: 78
Kelowna, B.C., Canada
Measured it with a fluke multimeter.


#205545 - 03/02/12 09:37 PM Re: 480 v hps lighting circuit [Re: Cinner]  
Tesla  Offline
Member
Joined: Jun 2004
Posts: 1,273
Sacramento, CA
Fluke multimeters ARE high impedance testers.

You need to use an old-style analog meter to load down these induced voltages. Since there is no current flow, it's really a capacitive effect.



Tesla

#205547 - 03/02/12 11:21 PM Re: 480 v hps lighting circuit [Re: Cinner]  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,799
Brick, NJ USA
Cinner:

You need a 'Wiggy', or any other brand solenoid type tester, or an analog multi-meter.


John

#205550 - 03/03/12 04:26 AM Re: 480 v hps lighting circuit [Re: HotLine1]  
sparkyinak  Offline
Member
Joined: Jul 2007
Posts: 1,313
Alaska
WIGGGGGGGY!!! I carry one in my pouch just for that


"Live Awesome!" - Kevin Carosa

#205556 - 03/03/12 06:36 PM Re: 480 v hps lighting circuit [Re: Cinner]  
Lostazhell  Offline
Member
Joined: Feb 2004
Posts: 1,428
Bakersfield, CA (Originally Or...
This happens in a cogen I work in alot.. 480V wiring from VFD loads seem to induce voltage on other conductors more than anything.. HID loaded circuits have the same tendency



Member Spotlight
dougwells
dougwells
kamloops BC Canada
Posts: 1,137
Joined: May 2003
Show All Member Profiles 
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.020s Queries: 15 (0.004s) Memory: 0.7822 MB (Peak: 0.9381 MB) Zlib enabled. Server Time: 2017-03-26 01:35:34 UTC