ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Danish type K Sockets
by winston_1 - 10/25/21 07:30 PM
Flexible Conduit?
by gfretwell - 10/24/21 01:59 AM
May I backfeed 3 phase transformer?
by dsk - 10/22/21 04:37 AM
Wire sizing
by gfretwell - 10/21/21 10:12 PM
GFCI's pops in large numbers
by dsk - 10/21/21 02:03 AM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
0 members (), 33 guests, and 16 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 3 1 2 3
Joined: Sep 2006
Posts: 98
A
Member
I recently completed a service to a 4 slip dock and a month later, received a call from the builder of said dock who told me the owner reported to him feeling a tingle when he and his sons approached the metal ladder while swimming. The power distribution is as follows: The meter and house are at the top of the hill with 4-#2 Al conductors about 750 feet to a panel on the cliff above the dock. Fron this panel I ran 110' of 6-4 SOOW through the water to the dock.

With one lead of my meter attached to some bare wire in the water, the metal of the dock shows 2.75 Volts. The system ground wire is carrying 1.8 Amps and if I pull the ground wire off the bar I get 8 Volts to the dock metal. With the mains to the house, garage and dock off I still have the same current flow, yet neither the new copper ground rod at the meter, nor the poco ground, nor their guy wire show any current flow. I have of course started communication with the engineer at the 'lectric co, but he hasn't been out yet. Any ideas as to what's happening here? Am I correct in wanting to disconnect my ground wire until the power company figures out what's happening? Obviously this is the thing that the $ 200 an hour professionals (called attorneys) pay for their own places on the lake with, so I want to solve this situation before it worsens.

Joined: Jul 2004
Posts: 783
L
Member
Is the house connected by a metallic path to any other systems such as cable TV, city water, city gas, sewer lines, etc? Perhaps some other house is using your ground wire as a ground path.

Check if some of the current is flowing across the water main bond. Also check if current is flowing thru the bonding wires for the telephone system and cable system.

Joined: Sep 2003
Posts: 650
W
Member

Here is a relevant thread over at Mike Holt:
http://forums.mikeholt.com/showthread.php?t=78799

In addition to checking for current flow from other systems as suggested above, also look for current flow between grounding electrodes.

-Jon

Joined: Jul 2004
Posts: 9,669
Likes: 6
G
Member
This might just be regular ground shift. You may never figure out where it comes from but the utility is certainly a suspect. Bear in mind the dirt is always a parallel current path in a grounded system. Have you tried establishing a local ground electrode system at the dock, connected to your equipment grounding conductor?


Greg Fretwell
Joined: Oct 2005
Posts: 40
G
Member
Hello,
I would check the service at the house first. Check the ground and the neutral/messenger at the house. It could be bad and all current running to the water. I put in ser and and 150amp diconnect/meter in my parents place a couple of years back. I cut free the service drop with gloves. When I reconnected the bare messenger first I got spark. When I finished my work, I looked at the neigbors house. Her messenger was broke and all the current was traveling through her water main and back through mine, out my messenger. Current loves the lowest resistance path home and just because the main is off in the house you are fed by, doesnt mean current can not come from a neighbors service. This is just some personal experience.


Brian Gibbons
Joined: Nov 2005
Posts: 826
J
Member
I'm not saying that this is a code requirement anywhere BUT: The only system that I would let anyone I loved around would include a transformer at the boat slip. Naturally, the secondary Neutral would be bonded to a locally established ground. That's the same thing I would have done where they were shocking all the dairy cows in the remotely fed barn.
Joe

Joined: Sep 2006
Posts: 98
A
Member
Thank you all for your input and comments.

Cable is from a dish on the house. Water is from a well on the premises, haven't checked the ground current on that possibility. This home is quite a distance from other structures, the closest house is 1/4 mile away and on its own xfmr. A local ground would have to be bare wire into the lake as the shoreline is at best a few feet of gravel over bedrock. The dock is moored to an almost vertical cliff face. I have current flow through the steel cables extending down to the downriggers that space the dock from the shore.

Joined: Mar 2004
Posts: 251
W
Member
I assume there are NO boats connected to this system when you show the current. A miss-wired boat or shore cord will sure cause this problem. Robert

Joined: Apr 2003
Posts: 362
Member
Are there any boats in the water connected to this power?
Ob


Choose your customers, don't let them choose you.
Joined: Oct 2005
Posts: 40
G
Member
Wow,
I am curious about this problem. The only thing I can think of is the dc battery system on the boat or the electrical on the boat itself. Maybe disconnect the negative on the dc battery system and turn shore power off and see if you have the same readings. Maybe a problem on the boat itself. Anyway, very interesting. Keep us posted when you figure it out.

Brian


Brian Gibbons
Page 1 of 3 1 2 3

Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Trumpy
Trumpy
SI,New Zealand
Posts: 8,407
Joined: July 2002
Top Posters(30 Days)
dsk 7
andey 1
Popular Topics(Views)
284,956 Are you busy
217,489 Re: Forum
203,777 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5