Old house, two prong outlets

[FunkyfullWidth]

I just bought an older home and ever room has only one outlet, and it is two prong. I've been doing alot of reading about upgrading to grounded outlets. Some places are saying that if you read 120 ac/v between the hot lead and the box or cover screw due to bx/armored cable then you can add a grounding wire from the receptical to the box. Others are saying that it still is not legal because the bx is not an "approved" ground and you run the risk of simply heating the bx cable up.
Would having ground wires in the panel change any of the answers about this? I remember seeing alot of bare wires in the panel.

last night I went to lowes to look for a cheap cirquit tester, a few 3 prong outlets and some bare grounding wire. There was a lowes employee/lurker that kept asking if I was finding everything ok (while I was in the electrical department.) So I told him what I was doing, and he simply said, he had no clue.... Then maybe switch to paint or garden if you have no clue.... besides the point.

I got home and using the circuit tester checked for 120, then checked between the hot side and cover screw and got 120.

Basically if I simply put a green ground wire between the box and the receptical without knowing about a bonding wire in the bx am I running a risk. Obviously, the safest course of action would be to rewire the hole damn house. but what are you guys opinions on this. Also, when would a 20amp receptical be needed. Are most outlets only 15 amp rated, or should I check the panel to see what the breaker is rated at and add recepticals according to the panel?

 

[matt151617]

You said there was a lot of bare ground wires in the panel... are those on the outlet circuits? My house was built in 1951, and was rewired in the 70s to early 80s. The ground wires are there, but wrapped around the clamp as it enters the box the outlet is in. Pull the clamp off of the box if you can and check for a green or bare ground wire in the BX (a little thin wire doesn't count). The problem with using the shell of the BX is the flex of the cable isn't the most reliable ground; someone could end up getting shocked if the ground isn't 100%. If there is a ground on the box, Lowes/HD sell pigtails with the screw already on it to ground the outlet to the box.

In my opinion, if there's isn't an actual ground in the BX, replace the circuits as you go with NM. Chances are the wiring is pretty old anyways. If there's a particularly difficult circuit to replace, you can make it safer by adding a GFCI outlet in the first outlet on the circuit, and labeling it "no equipment ground".

As far as the 20 amp outlet, you don't need one of those. 15 amp outlets on a 20 amp circuit are perfectly acceptable.

 

[jhelrey]

To be honest, I had 2 outlets that only had two prongs. I upgraded to three. While I could not find a ground wire, the box is metal as well as the conduit running to the box which runs to the panel. I figure it's grounded there.

 

[theoldwizard1]

A lot of this has to do with local codes. Unless you are doing a major remodel, you are usually not required to bring the wiring up to current code standards.

What you did would be considered "over kill" in some areas (The ground wire from the receptacle to the box is redundant. The mounting screws provide a ground path.) That is all I did in my home.

 

[Gooch]

A lot of this has to do with local codes. Unless you are doing a major remodel, you are usually not required to bring the wiring up to current code standards.

What you did would be considered "over kill" in some areas (The ground wire from the receptacle to the box is redundant. The mounting screws provide a ground path.) That is all I did in my home.

the screws only count if the recpt. is listed as 'self-grounding'

 

[Charles (in GA)]

Much ado about nothing. How many devices in the house actually have three prongs?

Lamps don't, you digital alarm won't, the toaster doesn't, only a few things like computers even have a ground pin on the plug.

In places where you may be using equipment with a ground pin, things such as un-interruptable computer power supplies, and computers themselves, run a special circuit for them, otherwise, don't waste your time.

Charles

 

[matt151617]

To be honest, I had 2 outlets that only had two prongs. I upgraded to three. While I could not find a ground wire, the box is metal as well as the conduit running to the box which runs to the panel. I figure it's grounded there.

There's a big difference between BX/armored cable and metal conduit. Metal conduit counts as a ground.

 

[FunkyfullWidth]

Well I was worried about it in my "guitar room." I have several electric guitars and would rather not get shocked while playing them. I'm not sure if that has anything to do with reverse polarity at the outlet or the ground... But all my amps and accesories have 3 prongs.

Then there's my tv, and my computer. Is there any sense in having a non-grounded surge protector?

 

[jhelrey]

There's a big difference between BX/armored cable and metal conduit. Metal conduit counts as a ground.

I assumed everyone knew I was talking about metal conduit.

It's metal conduit!

 

[matt151617]

Is there any sense in having a non-grounded surge protector?

Nope, they need a ground to work. Surge has to go somewhere.

 

[eljefino]

For all I know your guitar amp is grounded to cut the 60 hz "buzz". That would be a good test of how clean your grounds are, actually, if you can get it to buzz reliably.

To be pragmatic, if you don't put grounded outlets in, some jerk may come along later with a "cheater", of course not hook it up to the center screw, and that would be worse off.

Best answer is if you literally have one outlet per room, fish some modern NMT into the opposite wall and do it up right. Then leave the ungrounded outlets for convenience, if your homeowners insurance doesn't mind. What's your fusebox like? Spare room?

 

[FunkyfullWidth]

My circuit breakers are in the basement. No more fuses. I'm not sure when it was upgraded, probably the last 20 years or so.

 

[acer66]

Much ado about nothing. How many devices in the house actually have three prongs?

Lamps don't, you digital alarm won't, the toaster doesn't, only a few things like computers even have a ground pin on the plug.

In places where you may be using equipment with a ground pin, things such as un-interruptable computer power supplies, and computers themselves, run a special circuit for them, otherwise, don't waste your time.

Charles

This, I had the same problem and while I replace the wiring when I remodel a room in our house the only wire which really needed to be upgradet was a run for the ups for the work comp.

 

[rlitman]

Nope, they need a ground to work. Surge has to go somewhere.

That's not true, however without a ground you lose 2/3 of your surge fighting ability.

 

[westom]

Well I was worried about it in my "guitar room." I have several electric guitars and would rather not get shocked while playing them.

Wall receptacle can only provide a safety ground - not an earth ground. Code provides two options. Either route a grounded cable from the breaker box. Or install a GFCI either in that receptacle or in the breaker box.

Polarity is irrelevant to safety ground.

If a safety ground wire exists, ground will be apparent by inspection inside the box. If receptacles are two prong, then safety ground probably does not exist.

 

[2mJps]

If you dont have a ground and you replace outlets to 3 prong can you run a ground wire its not in conduit?

 

[FunkyfullWidth]

are you saying can I run a seperate ground wire? I don't have conduit I have the old bx romex type stuff. But If i'm going through the trouble of running just one wire, why not 3. Unless your asking your own question about snaking a ground through conduit...?

 

[2mJps]

I was looking at the cost and wonder if you could run a ground wire.

 

[theoldwizard1]

the screws only count if the recpt. is listed as 'self-grounding'

The only receptacle that I have seen that is NOT self-grounding is the isolated ground receptacle that are sometimes used in computer rooms and are colored bright orange !

 

[theoldwizard1]

Some places are saying that if you read 120 ac/v between the hot lead and the box or cover screw ...

That is pretty much what those cheap 3 prong outlet testers do. For less than $5 every homeowner should have one !

IMHO, this is adequate.

Well I was worried about it in my "guitar room." I have several electric guitars and would rather not get shocked while playing them. I'm not sure if that has anything to do with reverse polarity at the outlet or the ground... But all my amps and accesories have 3 prongs

Having a grounded outlet is not a guarantee that you won't be shocked. It helps but it is not a guarantee !

Are you saying can I run a seperate ground wire?

While in theory this should be adequate, it does not meet code and would be a big red flag if your house is ever inspected.

I don't have conduit I have the old bx romex type stuff.

BIG PROBLEM !! Your mixing your cable types. BX is a flexible metallic that typically has wire pre-installed.

Romex is a trade name (like Kleenex is for tissue) for "non-metallic" (NM) cable.

 

[theoldwizard1]

Okay, last post on this thread.

If, in fact, you only have 2 wire coming into your outlet, then install a GFCI. Use a power distribution strip if you need multiple 3 prong outlets.

What most people do not understand is that a GFCI works by measuring the amount of current flowing through the hot conductor and compares that to the amount of current flowing through the neutral. If they are not equal, you have a "leak" which could shock you.

The ground is not required and a sticker is included in the box that should be placed on the outlet if the GFCI is only connected to 2 wire.



If your equipment is old and has worn cords (not just the power cords), don't be surprised if the GFCI trips immediately.

 

[wyliesdiesels]

....While in theory this should be adequate, it does not meet code and would be a big red flag if your house is ever inspected....

Really? Ever read NEC 250.130C?

Equipment Fastened in Place or Connected by Permanent Wiring Methods (Fixed) — Grounding.
Unless grounded by connection to the grounded circuit conductor as permitted by 250.32, 250.140, and 250.142, non–current-carrying metal parts of equipment, raceways, and other enclosures, if grounded, shall be connected to an equipment grounding conductor by one of the methods specified in 250.134(A) or (B).
(A) Equipment Grounding Conductor Types. By connecting to any of the equipment grounding conductors permitted by 250.118.
(B) With Circuit Conductors. By connecting to an equipment grounding conductor contained within the same raceway, cable, or otherwise run with the circuit conductors.
Exception No. 1: As provided in 250.130(C), the equipment grounding conductor shall be permitted to be run separately from the circuit conductors.
Exception No. 2: For dc circuits, the equipment grounding conductor shall be permitted to be run separately from the circuit conductors.

 

[gayler]

Well I was worried about it in my "guitar room." I have several electric guitars and would rather not get shocked while playing them. I'm not sure if that has anything to do with reverse polarity at the outlet or the ground... But all my amps and accesories have 3 prongs.

Then there's my tv, and my computer. Is there any sense in having a non-grounded surge protector?

What kind of amp are you using? If it's a "vintage" tube amp with a two prong cord, you might be asking for trouble. If the polarity is not correct and you touch your micropnone while holding your guitar you could be electicuted. Always be sure your guitar amp and PA amp have three prong cords and are properly grounded!