2 prong- 3 prong GFIs?

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Old 09-03-00, 07:05 PM
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I wanted to change our 2 prong outlets to the 3 prong type but apparently this is against code because i do not have conduits. In an earlier topic someone had mentioned the use of a GFI to switch from a 2 prong to a 3 prong outlet. What exactly is GFI and how is this done?
 
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Old 09-03-00, 07:44 PM
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cat these are outlets that you can buy at your local electric supply [home depot ] they range from a couple of bucks to 12-15 bucks a piece i buy about the middle range ,they are a 3 prong outlet with a black and red button in the center of them just ask for a gfi NOW HEED THIS if you are not familiar with these i suggest you get a pro to come do at least 1 or 2 of them so you see how they are hooked up.IF you do the hook up read the instructions carefully and make sure power is off before doing the work
 
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Old 09-03-00, 09:10 PM
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A GFCI outlet or breaker is a device that, using electronics, measures current flow throught both wires in a circuit. Normally, when you hook-up a load (such as a drill) to an outlet, the curent will flow from the breaker through the black wire to the drill, then back to the panel on the white wire. If the drill has a short in it, and say the hot wire is touching the case of the drill, if you were to touch the case, and at the same time, touch some grounded surface, the current would flow from the drill case through you to the grounded object. This current would cause your heart to skip a beat, at the least, and could cause it it stop completely. If the same drill was protected by a GFCI (Ground Fault Circuit Interrupter), the electronics of the device would sense the current flowing somewhere else but back on the white wire, and shut off the power. This happens at a level low enough that your heart will not go into defib.

The GFCI is a safety device that has saved numerous lives, and will continue to in the future.

Hope this answers your question on GFCI.

PS For you perfectionists out there, I realize that the current does not actually flow as I illustrated, but rather is an alternating current. It is a little hard to show this to people who have no concept of electricity. For the purposes of this post, it will do.
 
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Old 09-04-00, 04:39 PM
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When you change old two prong receptacles, you have three options. Only two are explainable in my opinion in layman terms.

If you can find them you are allowed by Code to exchange a two prong receptacle with another new two prong receptacle. If you can find them.

The Gfi is the most common option. You have a few problems in design being compatable with old style wiring found with two prong receptacles.

In the years that two prong receptacles were installed originally, the wiring style was to run from the fuse to a light fixture in a room and then branch out in a mult finger method from the light fixture box as a junction box then to each receptacle from that same box. This makes it hard to find a place to install new GFI to monitor the whole circuit for those receptacles in one spot of the circuit.

If this is your wiring design that you are dealing with the GFI protection must be installed at the panel at the beginning of the circuit in order to make sure all replaced receptacles are protected by the GFI control. Now if you are using a breaker style panel then you can just use a GFI breaker and then install the receptacles with the black wire to the new copper screw and the white wire to the silver screw. Then ingnore the green screw.

If you are using a fuse style panel then you might want to mount a deep receptacle box below that panel, one for each circuit. Then run the black and the white wires from the panel neutral bar and from the fuse to the deep box. Now install a new GFI receptacle in that deep box. Connect the black wire from the fuse of the panel to the black wire or copper screw of the GFI marked line then connect the white wire coming from the neutral bar in the panel to the white wire or silver screw marked line of the GFI. Now connect the black wire going to the first light or receptacle on the circuit in the dwelling to the black wire or copper screw of the Gfi marked load. Then connect the white wire coming from the first receptacle or light in the dwelling to the white wire or screw of the GFI marked load.

The idea is to place the new GFI between the circuit going to the dwelling and the panel feeding that circuit. This will protect that circuit with the intent that the GFI control monitors the circuit in a manner that it will take the place of the third bare grounding wire.

An explaination of how a GFI works in a generic manner has already been explained to you in my opinion quite well. The only thing that I would like to add is that when us old folk were kids and we dropped a radio in the bath tub we were dead ducks. Now with the GFI control we have a half a chance. Much better than when we were kids, Huh. GFI controls have saved more lives since it was invented than you can imagine.

Word for thought. By the NEC we are going to be required to protect new bedrooms by installing a new device in year 2002. It is called a ARC FAULT control. This will be required to be installed in all new bedrooms starting year 2002. This new control is like the design of a GFI but it moniter sparking on a circuit that causes fires. This ARC FAULT Control is available now and can especially be usefull in old wiring designs to monitor loose connections that can cause fires. I think it will eventually save lives as much as the GFI had in the recent past.

Good Luck

WG
 
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Old 09-08-00, 10:47 AM
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Unless I missed a line somewhere, nobody has addressed the lack of an effective ground in the scheme of things. I would go to any length to get a ground wire to the circuit if going to a 3-prong receptacle, or I'd leave it 2-prong so that anyone who uses it knows the score up front. And correct me if I'm wrong, but a GFCI won't operate without a ground reference. And it is not a bridge between 2 and 3-prong outlets that magically makes things grounded where there was none before.

gls
 
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Old 09-08-00, 01:05 PM
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A GFCI simply senses a misflow of curren
on the neutral and hot wires. The GFCI itself
does not require a ground, but suppliments it, or replaces the safety aspect it if you use it without a ground. It does not replace an electrical ground, used for surge
protection, and EMI/RFI protection.
 
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Old 09-08-00, 01:40 PM
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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by geoffstephenson:
Unless I missed a line somewhere, nobody has addressed the lack of an effective ground in the scheme of things. I would go to any length to get a ground wire to the circuit if going to a 3-prong receptacle, or I'd leave it 2-prong so that anyone who uses it knows the score up front. And correct me if I'm wrong, but a GFCI won't operate without a ground reference. And it is not a bridge between 2 and 3-prong outlets that magically makes things grounded where there was none before.<HR></BLOCKQUOTE>

Going to any lengths could be quite expensive. If I remember correctly the code requires the ground wire to follow the same path as the power wires. That could be difficult to accomplish in old houses.

The code also specifies that 3 prong outlets that are not grounded, but protected by GFCI, are to be clearly marked as such. Most GFCI outlets come with a set of stickers for doing this.

And, no, a GFCI does not require a real ground to work. That is why the code specifically allows it to be used to protect ungrounded 3-prong outlets.
 
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