2-wire house vs 3-wire house

[WaterBoyz]

As mentioned in another thread, my son bought a house built in 1952. Some of the wirings are the original 2-wire and some upgrades to 3-wire have accrued.

When changing out the outlets there are some that are 2-wire supplied and have 3-wire devices installed. And some are 2-wire with 2-wire devices.

I did find a box that had the 3-wire in it with the original 2-wire in the same receptacle box. OK, fine, sorta. What I did notice was that the grounding wire (bare) of the 3-wire cable was secured to the neutral of the 2-wire cable.

I'm confused.

 

[wyliesdiesels]

wow couple code violations there

cannot put a 120v grounded outlet on a non-grounded circuit UNLESS there is a GFCi upstream of the 3-wire outlet.

Bonding neutral to ground on a circuit is done to fool testers. That needs to be fixed.

 

[Zeke]

First, check any 3 wire cables to see that the ground has continuity. See if that continuity is in fact tied back to the panel. To do that, you must trace circuits which is a good idea anyway if they are not all labeled. You can use a loud radio to trace circuits if nothing else. Any ground wires present in the panel should come out of the same conduit or cable as the hot and neutral. If there are more than one set coming in through the same conduit, it can get tricky.

Grounds have to be grounded, that's my point. You never know what the person before you did.

 

[theoldwizard1]

cannot put a 120v grounded outlet on a non-grounded circuit UNLESS there is a GFCi upstream of the 3-wire outlet

I did that at my daughter's first house, built in about 1948. Not cheap enough to do for every outlet, but worth the cost for the 2 or 3 that I did !

 

[Bert_]

I did that at my daughter's first house, built in about 1948. Not cheap enough to do for every outlet, but worth the cost for the 2 or 3 that I did !

Only need one per circuit if you can find the first outlet.

 

[walta]

Anyone who connects the neutral wire to a ground wire outside of the panel box had no respect for your life.

If for any reason, the neutral wire were to be disconnected or develop an open connection and you happened plug in a appliance with a metal case and a fault that energizing the case. You could get a deadly shock. Yes there are a few ifs and maybes but I don’t want to bet my life that they will not happen.

If it were me I would not use any 3 pin appliances without GFIC protection. If not someone could end up looking like your avatar.

Walta

 

[threeputt]

Great info. So if I replaced my first outlet where it leaves the breaker panel with a GFIC outlet I should be safe ? Wonder how many old homes have bootlegged grounds on the outlets so they can pass inspection ?

 

[WaterBoyz]

I did go through the panel to track down what was on what. This is the worst one.

All of this is on one 20 amp standard breaker:
Bedroom Master – light – ceiling
Bedroom Master – outlet – front
Bedroom Master – outlet – right
Bedroom Master – outlet – rear
Bedroom Master – outlet – left
Bedroom Corner – light – ceiling
Bedroom Corner – outlet – right front
Bedroom Corner – outlet – right rear
Bedroom Corner – outlet – left
Bedroom Corner – outlet – rear
Bedroom Front – light – ceiling
Bedroom Front – outlet – front
Bedroom Front – outlet – rear
Bedroom Front – outlet – left
Living Room – light – stairs upper & lower (3-way switch)
Outside – light – porch
Living Room – outlet – rear left
Living Room – outlet – front right lower
Living Room – outlet – front left (switched at front door)
Living Room – outlet – left front
Attic – light – ceiling x4
Attic – wired – roof fan
Outside – outlet – GFI – front window

I didn't pull the panel cover to verify the actual wire leaving the breaker. A lot of those devices have the original 2-wire that had the paper liner inside of the jacket. There are mostly old metal boxes. There is some 12/2 with ground mingled as well as some 14/2 with ground.

========

As some have said to add a GFI upstream but how does that work if it has no ground in the cable or no ground downstream?

========

Some circuits are fed by a double pole breaker but is labeled as 120V. Never seen that before.

========

Side note.
When the plumber cut the main water pipe inside the house, sparks flew and he was pushed back. Three circuit breakers popped.

May have that fixed by upgrading the 6awg ground wire from the ground rod outside to 4awg and installed 2 new ground rods and tied the hot and cold and gas line with 4awg as well as the main water pipe that attacked the plumber.

========

Question, does the guy wire that carries the two wires from the electric pole to the meter need connecting?

 

[WaterBoyz]

Great info. So if I replaced my first outlet where it leaves the breaker panel with a GFIC outlet I should be safe ? Wonder how many old homes have bootlegged grounds on the outlets so they can pass inspection ?

Would installing a GFI circuit breaker be better?

 

[Bert_]

Question, does the guy wire that carries the two wires from the electric pole to the meter need connecting?

That's not just a guy wire. It's the neutral!!!

Not being connected is a HUGE issue. Call your power company ASAP.

 

[Lassen Forge]

OK. Back in the "stone age" electrical wiring was 2 blade 2 wire, EXCEPT for industrial or specialized circuits. Protection was in the form of screw-in fuses that protected 4 circuits at either 15 (or in the kitchen) 20 amps. Normal was having ALL the lighting circuits on one, the kitchen (and maybe garage) on another, the plugs on one side of the house on the 3rd, and the other half on the 4th.

Black was hot. White was neutral. Ground was an adapter plug or through the conduit to a ground rod (or bus bar, depending on the local electrical code). Actually, some of the wiring was "neutraled" through a ground rod. (our house in Oakland, built in the early 30's, was like that).

If you had 220 (for your stove, maybe dryer if you had one) was a separate fused circuit, using 2 fuses (1 for each leg).

This was the state of affairs in 1938 when my parent's house was built. It never burned down, no one died from the electrical system, which ran like that until they upgraded it (along with a new HVAC system) in the early 80's. All us kids grew up with it.

Antiquated and obsolete? Sure it was, by modern standards. But it worked.

 

[PWC Repair]

Sounds like my house used to be......built in 1958. We found it easiest just to gut and remodel one room at a time. Good chance the old house has zero insulation in the walls like mine, common in the 50's. With a gutted room it's easy to replace all wiring, add outlets, and a junction box to make a new home run to the panel, insulate, new drywall, done.....piece of cake!

 

[WaterBoyz]

OK. Back in the "stone age" electrical wiring was 2 blade 2 wire, EXCEPT for industrial or specialized circuits. Protection was in the form of screw-in fuses that protected 4 circuits at either 15 (or in the kitchen) 20 amps. Normal was having ALL the lighting circuits on one, the kitchen (and maybe garage) on another, the plugs on one side of the house on the 3rd, and the other half on the 4th.

Black was hot. White was neutral. Ground was an adapter plug or through the conduit to a ground rod (or bus bar, depending on the local electrical code). Actually, some of the wiring was "neutraled" through a ground rod. (our house in Oakland, built in the early 30's, was like that).

If you had 220 (for your stove, maybe dryer if you had one) was a separate fused circuit, using 2 fuses (1 for each leg).

This was the state of affairs in 1938 when my parent's house was built. It never burned down, no one died from the electrical system, which ran like that until they upgraded it (along with a new HVAC system) in the early 80's. All us kids grew up with it.

Antiquated and obsolete? Sure it was, by modern standards. But it worked.

Yep, I grew up with the screw-in fuses. The local hardware store had a bunch as well as the corner 7-11 along with a vacuum tube tester.

Remember people putting a penny in there to get things going again?

 

[WaterBoyz]

Sounds like my house used to be......built in 1958. We found it easiest just to gut and remodel one room at a time. Good chance the old house has zero insulation in the walls like mine, common in the 50's. With a gutted room it's easy to replace all wiring, add outlets, and a junction box to make a new home run to the panel, insulate, new drywall, done.....piece of cake!

That gutting will have to be done someday for sure. Or at least a full electrical overhaul.

 

[wyliesdiesels]

I did go through the panel to track down what was on what. This is the worst one.

All of this is on one 20 amp standard breaker:
Bedroom Master – light – ceiling
Bedroom Master – outlet – front
Bedroom Master – outlet – right
Bedroom Master – outlet – rear
Bedroom Master – outlet – left
Bedroom Corner – light – ceiling
Bedroom Corner – outlet – right front
Bedroom Corner – outlet – right rear
Bedroom Corner – outlet – left
Bedroom Corner – outlet – rear
Bedroom Front – light – ceiling
Bedroom Front – outlet – front
Bedroom Front – outlet – rear
Bedroom Front – outlet – left
Living Room – light – stairs upper & lower (3-way switch)
Outside – light – porch
Living Room – outlet – rear left
Living Room – outlet – front right lower
Living Room – outlet – front left (switched at front door)
Living Room – outlet – left front
Attic – light – ceiling x4
Attic – wired – roof fan
Outside – outlet – GFI – front window

I didn't pull the panel cover to verify the actual wire leaving the breaker. A lot of those devices have the original 2-wire that had the paper liner inside of the jacket. There are mostly old metal boxes. There is some 12/2 with ground mingled as well as some 14/2 with ground.

Wow thats a lot on one circuit.

As some have said to add a GFI upstream but how does that work if it has no ground in the cable or no ground downstream?

A GFCI does NOT need a ground wire to function properly. this is because it reads the current on the hot and neutral. if they dont match by more than 5ma, then it trips.

A GFCI could care less whats going on on the ground wire. Under normal operation a ground wire doesnt even have current flowing on it.

Side note.
When the plumber cut the main water pipe inside the house, sparks flew and he was pushed back. Three circuit breakers popped.

May have that fixed by upgrading the 6awg ground wire from the ground rod outside to 4awg and installed 2 new ground rods and tied the hot and cold and gas line with 4awg as well as the main water pipe that attacked the plumber.

========

Question, does the guy wire that carries the two wires from the electric pole to the meter need connecting?

Wow. Hold up. This is serious.

So, the bare wire from the pole is NOT connected to your house service? If so, then this is why the plumber got nailed.

This bare wire is the neutral for your service. Because its not hooked up, the neutral current from the circuits is flowing on alternative pathways.

THIS NEEDS TO BE FIXED ASAP. It is a MAJOR fire hazard as anything in your house on a MWBC could be seeing upto 240v which can cause a fire.

Do you have a picture? Post it here.

BTW increasing the GEC wire size will NOT fix this issue with the open neutral on the service drop...

Call your PoCo STAT!!!

OK. Back in the "stone age" electrical wiring was 2 blade 2 wire, EXCEPT for industrial or specialized circuits. Protection was in the form of screw-in fuses that protected 4 circuits at either 15 (or in the kitchen) 20 amps. Normal was having ALL the lighting circuits on one, the kitchen (and maybe garage) on another, the plugs on one side of the house on the 3rd, and the other half on the 4th.

Black was hot. White was neutral. Ground was an adapter plug or through the conduit to a ground rod (or bus bar, depending on the local electrical code). Actually, some of the wiring was "neutraled" through a ground rod. (our house in Oakland, built in the early 30's, was like that).....

Thats incorrect.

A ground rod does NOT establish a low impedance fault current pathway for fault current to be able to trip a breaker.

Connecting a ground wire, aka EGC, to a ground rod will not function properly.

Ground rods are for lightening suppression.

The only way to establish a fault current pathway is by having the neutral to ground bond in the panel and ground wires bonding metallic pathways that should not be energized. Hence the ground pin on outlets.

There was NEVER a local code that permitted equipment grounding through a ground rod because that is functionally not possible.

As to the ground rod carrying neutral current, this happens when the neutral wire on the overhead or underground service has a bad, high impedance connection. The neutral current is taking another pathway. This is not acceptable and should be remedied.

 

[WaterBoyz]

Ok, I mentioned this earlier but here is a pic of it. This is on the circuit that I listed earlier on the 20amp.

The 3-white go to the wire nut in front.
1 white comes out of the wire nut and goes to the receptacle.
The 3-black go to the wire nut behind the mud ring.
1 black comes out of the wire nut and goes to the receptacle.
The bare ground comes out of the center cable and goes to the green box screw.
The bare ground (which was attached at one time?) to the green box screw, goes into a wire nut that is hidden from view.
A bare ground comes out of that hidden wire nut and then goes into the white wire nut.
A bare ground comes out of the white wire nut and then goes to the receptacle.

I have no idea where the 3 cables come from or go to.

Do I just reattach the bare ground to the green box screw and reattached the receptacle as it was before I removed it to change the receptacle color?

 

[wyliesdiesels]

since the box is metal and the outlet is most likely self grounding, you could attach the ground wire to the green screw in the box and forget about connecting the ground wire to the outlet. It would be grounded through the screws on the yoke.

 

[foolishpride]

Wow thats a lot on one circuit.



A GFCI does NOT need a ground wire to function properly. this is because it reads the current on the hot and neutral. if they dont match by more than 5ma, then it trips.

A GFCI could care less whats going on on the ground wire. Under normal operation a ground wire doesnt even have current flowing on it.



Wow. Hold up. This is serious.

So, the bare wire from the pole is NOT connected to your house service? If so, then this is why the plumber got nailed.

This bare wire is the neutral for your service. Because its not hooked up, the neutral current from the circuits is flowing on alternative pathways.

THIS NEEDS TO BE FIXED ASAP. It is a MAJOR fire hazard as anything in your house on a MWBC could be seeing upto 240v which can cause a fire.

Do you have a picture? Post it here.

BTW increasing the GEC wire size will NOT fix this issue with the open neutral on the service drop...

Call your PoCo STAT!!!



Thats incorrect.

A ground rod does NOT establish a low impedance fault current pathway for fault current to be able to trip a breaker.

Connecting a ground wire, aka EGC, to a ground rod will not function properly.

Ground rods are for lightening suppression.

Incorrect. GROUNDS, which ground rods are a part of, DO provide low impedance fault current paths to operate protective relaying schemes, which ultimately trip breakers.

This is taken right out of the NETA Grounding Course:


NOTES: Grounds have several protection applications:
Providing protection from natural phenomena such as lightning, grounds are used to discharge the transient energy before personnel can be injured or system components are damaged.
Providing protection from foreign potentials due to faults in electrical power systems, grounds help ensure rapid operation of the protective relays by providing low impedance fault current paths. This provides for the removal of the foreign potential as quickly as possible. The ground should drain the foreign potential before personnel are injured and the power or communications system is damaged.
Providing a safe path for dissipation of static and induced potentials, EMI, and RFI signals and interference.
Meeting NEC, OSHA, CSA, and other electrical safety standards.

 

[mike93lx]

Ok, I mentioned this earlier but here is a pic of it. This is on the circuit that I listed earlier on the 20amp.

The 3-white go to the wire nut in front.
1 white comes out of the wire nut and goes to the receptacle.
The 3-black go to the wire nut behind the mud ring.
1 black comes out of the wire nut and goes to the receptacle.
The bare ground comes out of the center cable and goes to the green box screw.
The bare ground (which was attached at one time?) to the green box screw, goes into a wire nut that is hidden from view.
A bare ground comes out of that hidden wire nut and then goes into the white wire nut.
A bare ground comes out of the white wire nut and then goes to the receptacle.

I have no idea where the 3 cables come from or go to.

Do I just reattach the bare ground to the green box screw and reattached the receptacle as it was before I removed it to change the receptacle color?

Please stop worrying about that overloaded circuit and address the neutral coming from the street. It is far more important

 

[wyliesdiesels]

Incorrect. GROUNDS, which ground rods are a part of, DO provide low impedance fault current paths to operate protective relaying schemes, which ultimately trip breakers.

This is taken right out of the NETA Grounding Course:


NOTES: Grounds have several protection applications:
Providing protection from natural phenomena such as lightning, grounds are used to discharge the transient energy before personnel can be injured or system components are damaged.
Providing protection from foreign potentials due to faults in electrical power systems, grounds help ensure rapid operation of the protective relays by providing low impedance fault current paths. This provides for the removal of the foreign potential as quickly as possible. The ground should drain the foreign potential before personnel are injured and the power or communications system is damaged.
Providing a safe path for dissipation of static and induced potentials, EMI, and RFI signals and interference.
Meeting NEC, OSHA, CSA, and other electrical safety standards.

Apples and oranges. Thats talking about lightening, induced current, EMI and RFI interference. Has nothing to do with what Im referring to.

A ground rod will not provide a low impedance fault pathway through the earth to trip a breaker for a branch circuit.

Ive seen it many times.

A ground fault in a detached structure(lets say no ground wire in the feeder and the neutral is unboned in the subpanel) will not find a low impedance fault current pathway through the earth and to the grounding rod on the structure with the main service panel.

But since you disagree how about you do an experiment and see for yourself.

 

[Bert_]

Incorrect. GROUNDS, which ground rods are a part of, DO provide low impedance fault current paths to operate protective relaying schemes, which ultimately trip breakers.

This is taken right out of the NETA Grounding Course:


NOTES: Grounds have several protection applications:
Providing protection from natural phenomena such as lightning, grounds are used to discharge the transient energy before personnel can be injured or system components are damaged.
Providing protection from foreign potentials due to faults in electrical power systems, grounds help ensure rapid operation of the protective relays by providing low impedance fault current paths. This provides for the removal of the foreign potential as quickly as possible. The ground should drain the foreign potential before personnel are injured and the power or communications system is damaged.
Providing a safe path for dissipation of static and induced potentials, EMI, and RFI signals and interference.
Meeting NEC, OSHA, CSA, and other electrical safety standards.

Go pound a ground rod and hook a hot wire off a breaker to it. It won't trip, if you don't believe it then go do it and prove us wrong. Your quote doesn't back up the argument you are trying to make.

 

[WaterBoyz]

Please stop worrying about that overloaded circuit and address the neutral coming from the street. It is far more important

Yes.

The electric utility will bury the cable after the existing gas pipe is relocated since it is in the way. The holidays have caused contractors slow to respond and slow to come out and slow to submit a quote.

 

[foolishpride]

Go pound a ground rod and hook a hot wire off a breaker to it. It won't trip, if you don't believe it then go do it and prove us wrong. Your quote doesn't back up the argument you are trying to make.

My statement stands. So if I take a cable off of a 138 KV Breaker and tie it to a driven ground rod, the relaying scheme won't trip the breaker? That would indeed be a hot wire. My point is, at low voltages, Wylie's statement would be correct. But that's dependent on many things like soil composition, moisture content of the soil, what month of the year, and salt content. That's the point I was making. Not trying to rattle cages, so relax.

 

[wyliesdiesels]

Yes.

The electric utility will bury the cable after the existing gas pipe is relocated since it is in the way. The holidays have caused contractors slow to respond and slow to come out and slow to submit a quote.

Are you actively using this house? If so, then you should not wait to fix it. Its a fire hazard.

Can you take a pic of it and post it here?

My statement stands. So if I take a cable off of a 138 KV Breaker and tie it to a driven ground rod, the relaying scheme won't trip the breaker? That would indeed be a hot wire. My point is, at low voltages, Wylie's statement would be correct. But that's dependent on many things like soil composition, moisture content of the soil, what month of the year, and salt content. That's the point I was making. Not trying to rattle cages, so relax.

again this is apples to oranges.

Youre comparing HV utility distribution to low voltage residential systems. They are not the same and they behave differently.

Were not discussing high voltage 138KV, were discussing low voltage 120v to ground voltages.

you just cant compare the 2.

The earth will not conduct enough fault current at low voltage to provide the high current necessary to the neutral bond in the panel in order for the breaker to clear the fault.

 

[mm08822]

NEC requirement for a grounding electrode resistance on a 120/240 single phase service to ground is 25 ohms or less. If one chooses to not test and prove that, then drive another rod and code requirement is satisfied.

Let's assume with one or even 2 rods driven there is 24 ohms to ground (could be way higher or less, but no one checks). Forget about wire resistance along the fault path and resistance at the point of fault.
120 v /24 ohms = 5 amps. No residential cb will be tripping at that magnitude of current. Certainly enough voltage on this "safe" conductor to kill someone if they were to happen across this now current carrying conductor.

As you stated, soils conditions, moisture content, salt content, etc. will all provide a daily variable to the resistance thru the earth. It is for this reason that an earth driven fault path is not permitted and an equipment grounding conductor is required. The egc is what provides the permanent predictable fault path necessary to quickly clear a fault by tripping the branch circuit ocp.

No one at the residential level is measuring/maintaining grounding electrode resistance to earth.
Protective relaying in a residence - nope.
Monitoring of fault current along the gec in a residence - nope.
138kv vs 120v = factor of ~1,100. 1 ohm difference on 138kv system is a significant amount of current easily measured and responded to.

 

[captaindiode]

If your neutral from the pole to the service entrence is broken, do not wait for the power company to "get around" to burying new wire. If you are using the service it should be fixed TODAY. Call the power company and tell them them you believe the neutral is disconnected.

Here is some info on the dangers of an open neutral from Mike Holt's site:

https://www.mikeholt.com/mojonewsarchive/NEC-HTML/HTML/DangerofOpenServiceNeutral~20020816.htm

 

[Terry D]

This pretty well explains on a low voltage system, the ground rod is there for lightning strikes. It also explains how just a ground rod cant be the sole path for fault current, it will not trip the breaker.

https://www.mikeholt.com/instructor2/img/product/pdf/1292432628sample.pdf