electrical outlets...i have four wires

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Old 06-18-06, 02:22 PM
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electrical outlets...i have four wires

hello all! i am new to this forum and a new homeowner. i have a lot of total noob questions, so bear with me.

i am trying to replace all my outlets in my house (built in 1950) - 'cause they are old and cruddy looking. so, i went out and bought about 12 polarized, grounded outlets, figuring hey, that's standard, right?

well, some of my outlets have grounded receptacles, but no grounding wire. some outlets have just the two-prong outlet. and in the junction box, some have 3 wires, some have 2 wires and some have 4 wires. basically, a hodge-podge of stuff here. so, here's my questions:

* i have four wires coming out of a lot of my junction boxes. what does that mean? there's no grounding wire, just two black, two white.

* do i break the metal tab when there are four or two wires?

* what does breaking the metal tab do?

* if i don’t have a grounding wire, will putting in grounded outlets be a problem?

* if i don’t have a grounding wire, how do i get a grounded outlet? can a grounding wire be “put in”?

* can i replace a two-prong outlet with a three-prong outlet?

if anyone can answer any or all of these questions, it would be greatly appreciated. thanks so much in advance.
 
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Old 06-18-06, 02:38 PM
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* i have four wires coming out of a lot of my junction boxes. what does that mean? there's no grounding wire, just two black, two white.
It depends on what, if anything, they are hooked to in the box.

* do i break the metal tab when there are four or two wires?
it depends on if the recep was intended to have two circuit going to it. In many houses there is a (or many) switched recep for lighting. often only one of the two receps of the duples was switched.

* what does breaking the metal tab do?
it isolates the two receps (electrically) so you can use
different circuits to power each recep.
* if i don’t have a grounding wire, will putting in grounded outlets be a problem?
yes, it is improper and against code, unless you have a ground wire to attach to the ground terminal. Either use non-grounded receps or replace with GFCI receps and use the "not a grounded recep" sticker on them.
* if i don’t have a grounding wire, how do i get a grounded outlet? can a grounding wire be “put in”?
Yes but it can be a real chore. Most people choose not to tear out the walls for a ground wire. See above for other methods

* can i replace a two-prong outlet with a three-prong outlet?
see above concerning GFCI outlets
 
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Old 06-18-06, 03:15 PM
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I will try to address your questions.

two black and two white wires usually means that the circuit powers this receptacle and then continues on to another receptacle. Look at the receptacle you removed. If it had the tabs broken (probably not) then break them to match. However, do not use a grounded receptacle. You cannot install a grounded receptacle where there is no ground.

Breaking the metal tab separates the top half of the receptacle from the bottom half. Breaking the tab on both sides completely separates the two halves, while breaking it on one side separates it only on that side. Tabs are most often seen broken in a residence when half the receptacle is switched, such as in a bedroom.

As I said before. Do no install grounded receptacles if there is no ground method provided. This is against code and extremely dangerous. A ground wire can be added, nut it is usually the same amount of work and better to replace the wiring. A better plan is to add new receptacles on a new circuit where you need the grounded receptacle.
 
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Old 06-18-06, 04:09 PM
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Congrats on the new crib.

You should get two books (or more) to read to familiarize yourself. Any homeowner would find them informative. You don't have to read them cover-to-cover.

Wiring Simplified, Richter - Home Depot or Menards, cheap
Electrical Wiring Residential, Mullin - Check your library, expensive
 
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Old 06-18-06, 05:46 PM
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thanks for the reponses everyone. i have a feeling that the outlets i DID do will have to be redone. i am having an electrician come over tomorrow. i am going to have him do some of the outlets and watch and learn at the same time. ah, the joys of homeownership.

so, even if i put a grounded outlet in an area with no ground wire, this is against code? what happens if plug a three-pronged appliance into this outlet? since there's no wire connected to the ground part of the outlet, what's the problem? again, i am a total newbie to this stuff, so please be nice! i am just trying to learn.
 
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Old 06-18-06, 05:55 PM
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Originally Posted by ArgMeMatey
Congrats on the new crib.

You should get two books (or more) to read to familiarize yourself. Any homeowner would find them informative. You don't have to read them cover-to-cover.

Wiring Simplified, Richter - Home Depot or Menards, cheap
Electrical Wiring Residential, Mullin - Check your library, expensive
would the 2002 version of "wiring simplified" do? it's much cheaper on amazon.com. or would you really recommend the 2005 version?
 
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Old 06-18-06, 06:53 PM
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Let me try to answer your question regarding plugging a three pronged cord into a non-grounded receptacle.

The third prong of a three prong cord is for a ground. This connection exists for one of two reasons. Either the ground is needed for safety or the ground is needed for reference.

When a ground is used for safety, it is used to protect the metal shell of a tool or appliance. Let's use a refrigerator as an example. The metal shell of the refrigerator is connected to the ground. If a hot wire should come loose in the refrigerator and accidentally contact the metal shell of the refrigerator, any electric current will find an immediate path via the ground wire back to the main electrical panel, where it will harmlessly return to the source, and cause the circuit breaker to trip or the fuse to blow.

However, if the metal case is not properly grounded, either because the receptacle is not grounded or because someone cut the third prong off the plug to make it fit into an older receptacle, the current will not have a path back to it's source. It won't, that is, until some unsuspecting person touched the case and at the same time touches the faucet. That person will then get 120 volts across their body.

When a ground is used for reference, it is usually for electronics. Power supplies in computers, televisions, DVD players, stereos, and all types of electronics produce voltages that the devices need to work properly. While these voltages are relatively small, usually 24 volts or less DC, if they are ungrounded, they may be floating at a much higher voltage. This can cause damage to the device, especially if multiple devices are connected together by wires or cables.

There is a third use for the ground. Surge suppressors use the ground as a way to dispense with a voltage spike they capture. The excess voltage is dissipated via the ground wire, instead of through your expensive computer or plasma television.
 
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Old 06-18-06, 07:12 PM
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thanks bob for the reply! i will have to redo most of the outlets i already did then. but i am learning. so, what do i do if i need a grounded outlet in my bedrooms but only have the two-pronged outlets? would a GFIC outlet take care of the problem?

thanks again for your help.
 
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Old 06-18-06, 07:41 PM
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A GFCI receptacle will make it safe to use a device that uses the ground for safety. It will not help a device that uses the ground for reference.

The most appropriate solution is to have several new receptacles added that are properly grounded.
 
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Old 06-18-06, 07:44 PM
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Originally Posted by racraft
A GFCI receptacle will make it safe to use a device that uses the ground for safety. It will not help a device that uses the ground for reference.

The most appropriate solution is to have several new receptacles added that are properly grounded.
thank you so much for all your help! so, i am guessing it's kinda expensive to add new grounded receptacles since i don't see a grounding wire anywhere in the junction box, right?
 
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Old 06-19-06, 12:36 AM
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i am guessing it's kinda expensive to add new grounded receptacles
It's a matter of access. In a one story house with at least easy access from the attic or basement or in a two story house with access from both below the first floor and above the second floor it may be easy to do without opening walls. If you have to open walls then it gets even more expensive.

Basically you must run new wires. You could run just ground wires but it is as easy and materials wise costs only a little more to run new cables. If you learn how to wire you may be able to do it yourself.

If your local code does not require metal boxes I would suggest removing each box from the wall then use the hole to fish a new cable from above or below. Disconnect the original cable(s) from their source and leave in the wall. Replace the original box with a plastic old-work box. This type of box has tabs to hold it and does not require fastening to the stud.

Removing the old box may be the trickiest part. Since the old-work boxes you are using as replacements though require a slightly bigger hole you can slightly enlarge the hole to make removing easier. A Sawzall (tm) is great for this but a hacksaw blade wrapped on one end with tape to make a handle will work. Assuming the box is nailed to a stud with a pry bar pry it from the stud about 1/8 inch and then use your saw to cut the nails. Loosen the cable clamps and pull the box out of the wall. You now have a hole to pull new wire.
 
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Old 06-19-06, 06:47 AM
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Originally Posted by callisto9
would the 2002 version of "wiring simplified" do? it's much cheaper on amazon.com. or would you really recommend the 2005 version?
Always best to buy the current version because it's less confusing but you can also get the changes from http://www.leviton.com/pdfs/nec/NEC_2005.zip

I think I got my 1999 version in 1998 or 1999 for less than $10 locally. I suspect you could get a similar price and avoid shipping costs.
 
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Old 06-19-06, 07:07 AM
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Originally Posted by ArgMeMatey
Always best to buy the current version because it's less confusing but you can also get the changes from http://www.leviton.com/pdfs/nec/NEC_2005.zip

I think I got my 1999 version in 1998 or 1999 for less than $10 locally. I suspect you could get a similar price and avoid shipping costs.
i think the 2002 book should do me just fine then. thanks for the help! i got the 2002 version on amazon.com for .99 cents ($4.50 with shipping). thanks again for the recommendation. let's hope the book isn't over my head.
 

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Old 06-19-06, 07:46 AM
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There is one other possible option that nobody mentioned. If your house was installed with BX cable, and metal boxes, you may have a perfectly legal grounding system already installed. BX cable (now commonly called AC) was in wide use in the 50's as a cabling method. The sheathing of the BX cable is an adequate and legal grounding system. The only potential issue is with continuity back to the panel.

If your house uses BX cabling, and you can ensure the continuity all the way back to the panel (an ohm meter and access to a near by water pipe can make this realativly easy) then you can simply add a pigtail from the back of your metal box to the grounding screw on your receptacle.

Good luck
-Matt
 
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Old 06-19-06, 08:05 AM
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Originally Posted by mherbert0
There is one other possible option that nobody mentioned. If your house was installed with BX cable, and metal boxes, you may have a perfectly legal grounding system already installed. BX cable (now commonly called AC) was in wide use in the 50's as a cabling method. The sheathing of the BX cable is an adequate and legal grounding system. The only potential issue is with continuity back to the panel.

If your house uses BX cabling, and you can ensure the continuity all the way back to the panel (an ohm meter and access to a near by water pipe can make this realativly easy) then you can simply add a pigtail from the back of your metal box to the grounding screw on your receptacle.

Good luck
-Matt
i have no idea! thanks for the info. i will make sure to ask the electrician this evening. thanks!
 
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