ground wires...

3780 Views 35 Replies 8 Participants Last post by TTW, Dec 20, 2012

dudeman

Discussion Starter · Dec 16, 2012

i have a ceiling llight box (the metal box that the romex goes in i dont know the techical name of it) anyway the wires that go into it that my light wires up to doesnt have a ground wire. its an old house with just 2 wires. would it be ok to run another length of romex up to the ceiling box, pigtailing the ground wire from one end of the romex wire from the plug outlet just for the use of the ground wire?

im looking to run a ground wire off of another ground wire using a length of romex..

hope this makes sense

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AllanJ

· #2 · Dec 16, 2012 (Edited)

A piece of Romex to a nearby grounded receptacle will not suffice as a ground (provide an equipment grounding conductor) unless the power for the light fixture also came through that piece of Romex.

In addition (you mentioned that the house is fundamentally 2 wire), the box with the receptacle and its feed must have been upgraded (or newly installed) so as to be grounded.

Technically you may not add things onto a circuit that is not compliant for example is not grounded. So you really may not add the light fixture to an existing ungrounded circuit but rather would have to string a new circuit up from the panel.

Now you can run a separate ground wire from the item you want grounded all the way down to the panel, exactly, approximately, or vaguely following the route of the circuit conductors feeding that item. This separate EGC may or may not be in a piece of Romex but if it is, you might as well run it as a brand new circuit.

Generally you may leave existing ungrounded light fixtures ungrounded until you are ready to upgrade the circuits feeding them. They don't get touched a lot so as to make you concerned about electrocution although it is a good idea to flip off the breaker before changing the lamp (bulb).

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NJMarine

· #3 · Dec 16, 2012

AllanJ said:
A piece of Romex to a nearby grounded receptacle will not suffice as a ground (provide an equipment grounding conductor) unless the power for the light fixture also came through that piece of Romex.

In addition (you mentioned that the house is fundamentally 2 wire), the box with the receptacle and its feed must have been upgraded (or newly installed) so as to be grounded.

Technically you may not add things onto a circuit that is not compliant for example is not grounded. So you really may not add the light fixture to an existing ungrounded circuit but rather would have to string a new circuit up from the panel.

Now you can run a separate ground wire from the item you want grounded all the way down to the panel, exactly, approximately, or vaguely following the route of the circuit conductors feeding that item. This separate EGC may or may not be in a piece of Romex but if it is, you might as well run it as a brand new circuit.

Generally you may leave existing ungrounded light fixtures ungrounded until you are ready to upgrade the circuits feeding them. They don't get touched a lot so as to make you concerned about electrocution although it is a good idea to flip off the breaker before changing the lamp (bulb).

If you install a piece of romex from recepticle to the light for the ground that would acceptable. Wire nut the black and white. This wire could be claasified for future use, but using the ground wire at this time.

dudeman

Discussion Starter · #4 · Dec 17, 2012 (Edited)

without running new wire from the panel to the light, is there a way to add a ground wire?

let me rephrase my question.
im using the existing 2 wire ceiling light (no longer using the actualy ceiling light) to power an outlet instead.

is there a way to ground the outlet without running new wire to the panel?

stickboy1375

· #5 · Dec 17, 2012

echobravo said:
i have a ceiling llight box (the metal box that the romex goes in i dont know the techical name of it) anyway the wires that go into it that my light wires up to doesnt have a ground wire. its an old house with just 2 wires. would it be ok to run another length of romex up to the ceiling box, pigtailing the ground wire from one end of the romex wire from the plug outlet just for the use of the ground wire?

im looking to run a ground wire off of another ground wire using a length of romex..

hope this makes sense

Install a GFCI breaker and call it good.

TTW

· #6 · Dec 17, 2012

You used to be able to run an 'extra' ground wire, but the 2011 code changed this (or was it 2008).

New code is to install a GFCI outlet leaving the ground unconnected, or as stickboy said, put in a GFCI breaker. The breaker is better as it will protect the whole circuit, not just that outlet.

Note, this will not provide a ground for electronics, but should protect against shocks / electrocution.

Jim Port

· #7 · Dec 17, 2012

Article 250.130 was not changed. It still allows a EGC to be run to ground to older wiring.

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Hardway

· #8 · Dec 18, 2012

You used to be able to run an 'extra' ground wire, but the 2011 code changed this (or was it 2008).

New code is to install a GFCI outlet leaving the ground unconnected, or as stickboy said, put in a GFCI breaker. The breaker is better as it will protect the whole circuit, not just that outlet.

Article 250.130 was not changed. It still allows a EGC to be run to ground to older wiring.

I got a little confused; I must be tired or missed something.
So can I run a single ground wire from the panel to an outlet on a two wire circuit?
Also on a GFCI outlet leaving the ground unconnected cause the GFCI trip.

TTW

· #9 · Dec 18, 2012

Thanks guys, I'll go read it again. I do my best to be correct but I am glad you have my back!:yes:

Ok, so a new EGC has to go back to the panel, right?

Or a GFCI will meet code.

So who wants to explain how a GFCI works without a ground. I'm willing to give it a go!

Jim Port

· #10 · Dec 18, 2012

There are a couple of acceptable places to connect the new EGC for the old 2 wire circuit. The panel where the circuit originates is one place.

The GFI measures the difference in current between the hot and neutral. If it is off by 5 mA the GFI will trip.

stickboy1375

· #11 · Dec 18, 2012

TTW said:
So who wants to explain how a GFCI works without a ground. I'm willing to give it a go!

The device doesn't measure anything on a EGC, just the hot and neutral conductor....

TTW

· #12 · Dec 18, 2012

250.130 Equipment Grounding Conductor Connections.
Equipment grounding conductor connections at the source
of separately derived systems shall be made in accordance
with 250.30(A)(1). Equipment grounding conductor con-
nections at service equipment shall be made as indicated in
250.130(A) or (B). For replacement of non–grounding-type
receptacles with grounding-type receptacles and for branch-
circuit extensions only in existing installations that do not
have an equipment grounding conductor in the branch circuit,
connections shall be permitted as indicated in 250.130(C).
(A) For Grounded Systems. The connection shall be
made by bonding the equipment grounding conductor to
the grounded service conductor and the grounding elec-
trode conductor.
(B) For Ungrounded Systems. The connection shall be
made by bonding the equipment grounding conductor to the
grounding electrode conductor.
(C) Nongrounding Receptacle Replacement or Branch
Circuit Extensions. The equipment grounding conductor
of a grounding-type receptacle or a branch-circuit extension
shall be permitted to be connected to any of the following:
(1) Any accessible point on the grounding electrode sys-
tem as described in 250.50
(2) Any accessible point on the grounding electrode con-
ductor

This is where the building is grounded at the main panel

(3) The equipment grounding terminal bar within the en-
closure where the branch circuit for the receptacle or
branch circuit originates
(4) For grounded systems, the grounded service conductor
within the service equipment enclosure
(5) For ungrounded systems, the grounding terminal bar
within the service equipment enclosure
Informational Note: See 406.4(D) for the use of a ground-
fault circuit-interrupting type of receptacle.

(2) Non–Grounding-Type Receptacles. Where attachment
to an equipment grounding conductor does not exist in the
receptacle enclosure, the installation shall comply with
(D)(2)(a), (D)(2)(b), or (D)(2)(c).
(a) A non–grounding-type receptacle(s) shall be per-
mitted to be replaced with another non–grounding-type re-
ceptacle(s).
(b) A non–grounding-type receptacle(s) shall be per-
mitted to be replaced with a ground-fault circuit interrupter-
type of receptacle(s). These receptacles shall be marked
“No Equipment Ground.” An equipment grounding con-
ductor shall not be connected from the ground-fault circuit-
interrupter-type receptacle to any outlet supplied from the
ground-fault circuit-interrupter receptacle.
(c) A non–grounding-type receptacle(s) shall be per-
mitted to be replaced with a grounding-type receptacle(s)
where supplied through a ground-fault circuit interrupter.
Grounding-type receptacles supplied through the ground-
fault circuit interrupter shall be marked “GFCI Protected”
and “No Equipment Ground.” An equipment grounding
conductor shall not be connected between the grounding-
type receptacles.

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TTW

· #13 · Dec 18, 2012 (Edited)

AC power flows in two directions, from hot to neutral, then from neutral to hot, it switches directions back and forth 60 times a second. Think of a lamp with a two prong connector, it doesn't need a ground to light up.

The GFCI senses the amount of current going in one direction and compares it to the amount of current going the other way. It does this very well.

So lets say that lamp had an electrical leak and you touched it. You are wearing sneakers and are not touching anything else. You would not get a shock because there is no path through you to anywhere the electricity might go.

Then you touch a metal water pipe and zap you get shocked. Why? because some of the electricity found an easier way through you to do what it really likes to do, to return to it's source, the transformer at the pole (usually through the ground).

Lets say the lamp was grounded and a nasty short developed. That power would head off to ground lickety split and suddenly instead of the power draw of a light bulb, a whole lot of power is flying through the circuit breaker. So much power that the circuit breaker says Pull Over! and trips and the circuit goes dead.

Now lets say the lamp (not grounded again) has a small leak of current, not so much that the breaker trips, or maybe the breaker malfunctions, and you touch it again and grab that handy water pipe and you get badly shocked or worse.

OK, long winded I know, gotta lay off the coffee...

So now we plug our 2 prong ungrounded lamp into a GFCI

The GFCI says, lets see, I got 833.7 mili-Amps going this way and 833.1 mA going that way, no problem... Allright 831.4 mA - 832.2 mA Okee Dokee.... You get the idea...

and you touch the lamp and the water pipe again (why you would do this again I don't know).

Now the GFCI sees 829.0 mA - 834.2 mA AND SAYS WOHA NELLIE!!!!!! Theres 5.2 mA MISSING !!!!!!

I don't know where it's going, I don't care if it's going to Jupiter through the CAT! I just know that it's going SOMEWHERE it's not supposed to !!!!!

and the GFCI trips and saves your life. No ground required. They say these things trip so fast, you probably will feel a shock, but it won't kill you.

They are designed to trip at 5/1000 of an amp, that's 0.005 amps. A 100 watt light bulb only draws draws about 8/10 or 0.08 amps (or about 16 times more power) just to give you an idea.

Whew, I'm getting another coffee!

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stickboy1375

· #14 · Dec 18, 2012

Few fixes in your long winded explanation, first off electicity does not seek the ground/earth, it returns to the source, which is the transformer at the pole. Secondly, you will feel a shock from a gfci, but you will most likely live.

Reactions: 2

TTW

· #15 · Dec 18, 2012

Got it

dudeman

Discussion Starter · #16 · Dec 18, 2012

Jim Port said:
Article 250.130 was not changed. It still allows a EGC to be run to ground to older wiring.

sorry i dont know what an EGC is.. can you break it down in simple terms?

and does this mean a separate ground wire is ok to run?

the only thing being plugged into this outlet is a light.

dudeman

Discussion Starter · #17 · Dec 18, 2012

TTW said:
250.130 Equipment Grounding Conductor Connections.
Equipment grounding conductor connections at the source
of separately derived systems shall be made in accordance
with 250.30(A)(1). Equipment grounding conductor con-
nections at service equipment shall be made as indicated in
250.130(A) or (B). For replacement of non–grounding-type
receptacles with grounding-type receptacles and for branch-
circuit extensions only in existing installations that do not
have an equipment grounding conductor in the branch circuit,
connections shall be permitted as indicated in 250.130(C).
(A) For Grounded Systems. The connection shall be
made by bonding the equipment grounding conductor to
the grounded service conductor and the grounding elec-
trode conductor.
(B) For Ungrounded Systems. The connection shall be
made by bonding the equipment grounding conductor to the
grounding electrode conductor.
(C) Nongrounding Receptacle Replacement or Branch
Circuit Extensions. The equipment grounding conductor
of a grounding-type receptacle or a branch-circuit extension
shall be permitted to be connected to any of the following:
(1) Any accessible point on the grounding electrode sys-
tem as described in 250.50
(2) Any accessible point on the grounding electrode con-
ductor

This is where the building is grounded at the main panel

(3) The equipment grounding terminal bar within the en-
closure where the branch circuit for the receptacle or
branch circuit originates
(4) For grounded systems, the grounded service conductor
within the service equipment enclosure
(5) For ungrounded systems, the grounding terminal bar
within the service equipment enclosure
Informational Note: See 406.4(D) for the use of a ground-
fault circuit-interrupting type of receptacle.

(2) Non–Grounding-Type Receptacles. Where attachment
to an equipment grounding conductor does not exist in the
receptacle enclosure, the installation shall comply with
(D)(2)(a), (D)(2)(b), or (D)(2)(c).
(a) A non–grounding-type receptacle(s) shall be per-
mitted to be replaced with another non–grounding-type re-
ceptacle(s).
(b) A non–grounding-type receptacle(s) shall be per-
mitted to be replaced with a ground-fault circuit interrupter-
type of receptacle(s). These receptacles shall be marked
“No Equipment Ground.” An equipment grounding con-
ductor shall not be connected from the ground-fault circuit-
interrupter-type receptacle to any outlet supplied from the
ground-fault circuit-interrupter receptacle.
(c) A non–grounding-type receptacle(s) shall be per-
mitted to be replaced with a grounding-type receptacle(s)
where supplied through a ground-fault circuit interrupter.
Grounding-type receptacles supplied through the ground-
fault circuit interrupter shall be marked “GFCI Protected”
and “No Equipment Ground.” An equipment grounding
conductor shall not be connected between the grounding-
type receptacles.

in simple terms this means?

TTW

· #18 · Dec 18, 2012

Someone will correct me if I am wrong.

The ECG, equipment grounding conductor, is the big ground wire that grounds the whole system. It's the wire connected to the 8 foot ground rods driven into the dirt and your main water pipe where it enters your house. It connects to your meter box or main breaker panel. It's the main protection against lightning and things like tree branches hitting power lines.

(I think I have this right)

This is what you have to connect to, the easiest point is in the main breaker panel.

Yes the code is complicated and quite a maze to figure out, but electricians have to know it to get licensed.

Dave632

· #19 · Dec 18, 2012

TTW said:
They are designed to trip at 5/1000 of an amp, that's 0.005 amps. A 100 watt light bulb only draws draws about 8/10 or 0.08 amps (or about 16 times more power) just to give you an idea.

Whew, I'm getting another coffee!

A little bit of a math fix.

Power = Voltage * Current --> Current = Power / Voltage

For a 100W bulb in a 120V circuit:

Current = 100 / 120 = 0.833 Amps (not 0.08 Amps), which is 160 times more current than it takes to trip a GFCI.

Reactions: 1

AllanJ

· #20 · Dec 18, 2012 (Edited)

An equipment grounding conductor (EGC) is the ground wire that goes with the hot wires for example in a branch circuit, in an appliance cord, or between a main panel and subpanel. A grounding electrode conductor (GEC) runs from the panel to ground rods, water pipe, concrete rebar, or between such grounding electrodes. A bonding jumper interconnects metal objects (such as sections of metal plumbing with a plastic pipe separating them electrically) sometimes in the same manner as a GEC but does not specifically connect to a grounding electrode.

The grounding electrode system consists of all qualifying grounding electrodes (including the main water pipe, if metal) entering the building), the GECs, and the panel ground bus (neutral bus if in the panel with first main disconnect). An outbuilding that needs enough electricity so as to have a subpanel must have its own GES tied into the panel with the first master disconnect.

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