GFI Problem?

Reply

  #1  
Old 09-30-12, 02:51 PM
Member
Thread Starter
Join Date: Sep 2012
Location: USA
Posts: 1
GFI Problem?

I install an external circuit to a storage shed using a GFI outlet where the cable exists the house. All outlets tested fine using an outlet tester, and I passed the electrical inspection.

After about a week I plugged in a light in the shed but had no power. The GFI tripped and would not reset. I replaced the GFI and the new one would not reset.

Then I replaced the GFI with a normal outlet and all outlets tested OK.

Do I have bad luck picking GFIs or is there a problem downstream that the outlet tester is not picking up?

Thank for your help.

Ed
 
Sponsored Links
  #2  
Old 09-30-12, 04:25 PM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,675
What wiring method did you use to the shed? Was it UF-b or Romex or THWN in conduit? Did you extend the receptacle junction box with a weather resistant extension ring? Pictures of your installation on both ends might help us help you. http://www.doityourself.com/forum/li...-pictures.html
 
  #3  
Old 09-30-12, 04:47 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,221
Do I have bad luck picking GFIs or is there a problem downstream that the outlet tester is not picking up?
It seems obvious that your new circuit to the shed has a fault. Try disconnecting the run to the shed from the GFI receptacle and see if the GFI receptacle will now reset. I bet it will.
 
  #4  
Old 09-30-12, 05:27 PM
Member
Join Date: Sep 2012
Location: Canada
Posts: 12
GFI problem

A GFI shutoff power if there is a "lick" on the circuit.

if the white line from the panel is touching ground, then the GFI shutoff the circuit to prevent an accident happen.

the GFI wall box shuld be wider than the regular outlet box, if is not, is good idea to use electric tape around the GFI to avoid wires touching the box.

Mod/Tech Note: All three of the statements in this post are inaccurate. See reply.
 

Last edited by Nashkat1; 10-01-12 at 12:21 PM.
  #5  
Old 10-01-12, 12:59 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Antonio, all three of the statements in this post are inaccurate. I am posting this reply so that other members and readers can see accurate information on Ground Fault Circuit Interrupters, and how these vital - but often misunderstood - life safety devices work.

A GFI shutoff power if there is a "lick" on the circuit.
Beyond the fact that the term "lick" has no meaning in electrical terminology, this is not how a GFCI works. A GFCI device constantly monitors the power on an ungrounded conductor (a "hot" wire) and its associated grounded conductor (its "neutral"). The GFCI will open the circuit - interrupt the power on the ungrounded conductor - when there is an imbalance of power on that pair.

if the white line from the panel is touching ground, then the GFI shutoff the circuit to prevent an accident happen.
No. While a neutral and an equipment grounding conductor (a "ground") should never be connected anywhere downstream of the service entrance, that is not the type of problem that a GFCI is designed to prevent. Because it is a life safety device, a GFCI monitors the power returning on the neutral wire and compares that to the power going out on the hot wire. It will open the circuit, interrupting the power going out, when the power returning is even fractionally less than the power going out.

The amount of power on a hot wire and its associated neutral in a properly functioning AC electrical system are equal. The safety assumption, therefore, is that the missing ungrounded power found a different path to ground. That path could be through a human being - we make excellent conductors - and that the power needs to be shut off until the problem can be corrected. A connection between a grounded conductor and a grounding conductor does not create a condition that would trip the GFCI.

the GFI wall box shuld be wider than the regular outlet box, if is not, is good idea to use electric tape around the GFI to avoid wires touching the box.
Not only is this statement not true, there is no such box made. While the depth of the box, or internal obstructions within it, may present a challenge in installing a GFCI receptacle, all such receptacles are designed and manufactured to fit inside the vertical and horizontal dimensions of any standard wall box. Tape is not needed when the terminal screws are properly tightened, and may interfere with the special tape that should cover the LOAD terminals until and unless they are needed.

For more information, see GFCI's How They Work by Mike Holt.
 

Last edited by ray2047; 10-01-12 at 01:59 PM. Reason: Typo
  #6  
Old 10-01-12, 04:37 PM
Member
Join Date: Sep 2012
Location: Canada
Posts: 12
thanks for help me to understand better how the GFI work.
 
  #7  
Old 10-01-12, 04:54 PM
Member
Join Date: Oct 2012
Location: US
Posts: 23
cause of GFI trip is likely water

It islikely, that although you passed inspection, damage of some type has occured to your conduit or wire between the house and shed which has caused moisture to be present. You would also need a nick in insulation, but both of these could be caused by digging in the wire area or improper sealing of exterior connections.

Did you use wateproof wirenuts?
Did you use conduit? if so are there any conduit joints below grade?

I think you have a ground leak caused by a wire nicked and moisture or a poor wirenut connection with moisture present.

These are not only possible causes, but are the most likely IMO.
 
  #8  
Old 10-01-12, 05:05 PM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,675
Did you use wateproof wirenuts?
Except for underground splices there should be no need for "water proof" wire nuts. Splices should generally be above ground in weather proof boxes.
 
  #9  
Old 10-01-12, 07:18 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,221
Did you use conduit? if so are there any conduit joints below grade?

I see no merit here as all horizontal underground conduits greater than 10 feet in length will have at least one joint underground and typically, they are all full of water. This is a fairly new installation so the conduit may not be full yet, but it will be by spring. Have you disconnected the circuit from the load side of the GFI receptacle yet? Once you do, I would bet the GFI will reset properly.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'