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
Industrail Control Panel bonding per 409.108
by sparkyinak
Yesterday at 03:17 PM
Calling all Non-US members!! (Non-US only)
by aussie240
12/07/16 02:39 AM
Photo Upload Tutorial
by DanK
12/06/16 11:35 PM
Sprinklered equipment 26-008
by bigpapa
12/02/16 04:24 PM
On Delay Relay with Auto Reset
by Potseal
12/01/16 09:59 AM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 13
HotLine1 9
Texas_Ranger 8
sparkyinak 8
Trumpy 6
Who's Online
0 registered (), 192 Guests and 6 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#139956 - 01/06/04 03:39 PM Voltage at earth electrode
lyledunn Offline
Member

Registered: 06/30/02
Posts: 159
Loc: N.Ireland
On attempting to measure the earth electrode resistance on a single-phase TT installation using an AVO earth loop impedance tester, the instrument indicated over limit voltage of 290v and would not permit the test to proceed.
The P-N voltage was 235v. Unfortunately the operative did not measure neutral to earth voltage.
A contractor on site at the same time as our operative confirmed the 290v using a different voltage indicator.
I was intrigued and some days later I visited the site. Voltages seem to have returned to normal, 233v between live conductors and between phase and earth and 0 v between neutral and earth.
The supply to the installation is fed via a local three phase power company tx.

Care to speculate?
_________________________
regards

lyle dunn

Top
Test Equipment:

Large Selection of Test Equipment For Electrical, HVAC, Test & Measurement
Large Selection of Test Equipment For Electrical, HVAC, Test & Measurement

#139957 - 01/07/04 02:06 AM Re: Voltage at earth electrode
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Maybe a bad neutral somewhere on the network?

Top
#139958 - 01/07/04 10:30 PM Re: Voltage at earth electrode
chi spark Offline
Member

Registered: 01/06/04
Posts: 102
Loc: Chicago IL USA
Imbalance on delta tx?

Top
#139959 - 01/09/04 01:13 AM Re: Voltage at earth electrode
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
lyle,
Would you care to give the type of Line-Earth loop tester used? (ie: Model No.)
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

Top
#139960 - 01/09/04 02:35 AM Re: Voltage at earth electrode
lyledunn Offline
Member

Registered: 06/30/02
Posts: 159
Loc: N.Ireland
Trumpy,
Sorry Trumpy, misinformation! The instrument was actually a Robin loop tester. It appears that the indicated voltage can be out by 10% although this wouldnt have necessarily been the problem.
The installation was not connected to the supply at the time. The NIE engineer suggested capacitance which disappeared when the installation was connected. Not sure about that one!
Many thanks for your replies guys!
_________________________
regards

lyle dunn

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