gfci three black and two white wires??

im wiring a gfci in the kitchen and the outlet had three white and two blackwires. both black tested hot when paired with only one of the three whites or with the ground. ive tried as bunch of configs-cant get it and have outlets downstream that wont light up-any advice? thanx
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irishspring wrote:

Hi,
_____________________ Black-------( )-------------Black line ( GFCI ) load ( ) White ------(_____________________)-------------White
ground=green <<power source to breaker down stream outlet>>
Is this what you see? There must be an instruction sheet with the package. Did not get one?
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You won't have three black and two white wires unless they are pulled in some type of conduit. You need to determine how they were connected to the existing outlet. It is possible that the existing outlet was split on two circuits, or a switched circuit. If either was the case, the break off tab between the brass screws will be removed. In any case, separate all the wires, then with a tester, determine the black and white "feed" wires, which attach to the "line side of the GFCI, then try attaching the other wires to the "load" side, and see what you get

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On Sun, 23 Jul 2006 23:06:07 -0500, "irishspring"

I'm confused by this. You say you have two blacks, and three white wires?
And both blacks were hot?
Can you recheck this, and repost.
Thank you,
tom @ www.NoCostAds.com
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yes both black tested hot when coupled with one of the three white wires, i tested them one by one.
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RBM, its three white and two black. both black appear to be hot when tested with ground. only one of the three white wires will light up the black wires though. the other two white ones dont. thanx for any help
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Are these wires running through a conduit? Is it possible that one of the three white wires is just attached to the outlet box?

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ok closer inspection reveals three conduit wires coming into box where im trying to install GFCI. One has a black a white and a red- the red is connected to a black of another conduit. the two other conduits have just a black and a white each. the two free blacks test hot with either the ground or the white which comes from the conduit running the white black and red. any ideas on gfci line and load-what whites should go where? im pretty sure the conduit with blackwhiteand red is my line wire. thanx
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You line wire is probably 2 phase (red white is one phase, black white is another) feeding two different circuits downstream.
If you measure between black and red you should get 240V. Use a volt meter to measure instead of a hot/cold probe.
You need two gfcis to protect two different circuits. If you can only fit one GFCI in the box, then you can
(1) use only one of the two phase, in other words, combine the two downstream black/white together on the load side of the GFCI. However, this is probably a code violation and a bad idea. Usually builders don't pull a 2-phase line unless they have to. If this is in the kitchen, you are supposed to have 2 independent circuits of 20A, both protected by GFCI.
(2) pick one of the two circuits to protect with the GFCI and leave the other one unprotected
(3) install a bigger junction box and put two GFCI in there to protect two circuits. This is probably not easy unless you have an open wall
(4) put GFCI circuit breakers in the main panel to protect these two circuits, or one GFCI breaker and one GFCI receptacle
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He could put two GFCI outlets in the box and share the neutral on the "line" side, but he can't install GFCI breakers and share the neutral, it'll just trip the breakers

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That's right. You cannot use regular GFCI breaker at the panel side of a multiwire circuit. However, there seems to be a special breaker called a double pole GFCB for multiwire circuit. Judging from the lack of hits on google, it is probably a rare item.
Here's some info I found: http://www.petesdepot.com/522686.html http://www.handymanwire.com/ubbthreads/printthread.php?Cat=&Board=UBB2&main 8975&type=thread
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What it looks like you have, is an Edison circuit, which is two hot legs that share a common neutral. The conduit with the three wires would be the feeds. The red wire is a feed that just continues somewhere else. The problem is that you cannot share a neutral of a multiwire or Edison circuit off the "load" of a GFCI. You need to connect all three whites together with a fourth pigtail connected to the "line" neutral of the GFCI. Leave the black and red that are wirenutted together alone. Connect the two blacks together with a third pigtail to the "line" hot of the GFCI. You are now protecting that one location only. You need to go to the next outlet downstream and install anther GFCI, and continue doing this until you no longer have an Edison circuit involved

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thats great thanks ill do the pigtail of whites and just protect that one outlet which is all i need to do cause its the kitchen. thankseveryone
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