Living room outlet is 2-pronged. TV plug is 3. I am currently (heh) using a 3-to-2 prong adapter to allow plugability.
If I replace that 2-prong outlet with a GFCI outlet, would that be just as good and safe as wiring in a ground the ‘correct’ way?
And would doing this offer ground protection on other outlets in that circuit?
If you offer an answer please know what you are talking about. 
Thanks!
mmm
Yes, and it’s a good idea. Make sure to apply the “NO EQUIPMENT GROUND” sticker that comes with the GFCI.
Only if they are fed by the “load” side of the GFCI. Otherwise they will just be in parallel with the GFCI and will work the same as before. Whether this is feasible for your situation just depends on how the wiring is run in your walls. You may want to just replace all the outlets in that room with separate GFCIs.
A GFCI receptacle doesn’t provide a grounding conductor to anything. A functional GFCI will trip if it detects an imbalance between the hot and neutral currents of over about 5 milliamps. It will provide this type of protection to outlets that are downstream of it, assuming it’s wired correctly. So it will provide some safety from shocks.
Friedo and Dickerman are quite correct.
The other question that one might ask is, “Why is there a ground prong on the TV plug at all?” For some electronic equipment, having an earth ground could make a critical difference in reducing hum or improving reception using an antenna. I know nothing about your TV, but it probably has an antenna jack and may have internal shielding that works best when connected to an earth ground. This is not a safety issue as much as a performance issue. Audiophiles frequently find themselves tearing their hair out trying to resolve grounding and ground-loop problems when they connect components to each other.
If everything works fine with your adapter, I doubt that there is any problem in your case.
At the very least install a GFCI receptacle as mentioned by others.
And then there’s the curious question of why the TV is grounded. Devices are typically grounded when there’s a metal chassis accessible to the user. But most TVs don’t have a metal chassis. So I am not sure of the reason. Here are some ideas:
Excellent points. I composed the OP in haste with not enough thought.
The TV is actually plugged into a power strip that is 3-pronged.
Sorry for this critical omission.
mmm
I don’t suppose there is an easy way to determine this?
mmm
If you see more than one hot/neutral pair connected to the existing receptacle, you will need to determine which is connected to the circuit breaker and which is connected to down-stream receptacles.
To do this, turn off power to the existing receptacle (by flipping its breaker) and remove the receptacle. Make sure none of the copper wires are touching each other. Turn power back on, and then measure the voltage of each hot/neutral pair. The hot/neutral pair that has 120 VAC on it connects to the LINE side of the GFCI. All the other hot/neutral pairs (each of which should have 0 V on it) connect to the LOAD side of the GFCI. Turn power back off and install the GFCI.
I think mmm was asking how to tell which side of the GFCI is the LOAD side. The answer is it has the word “LOAD” written on it. The other side will say LINE.
Note that there may be only one wire connected to the terminals, but that wire then goes to a wire nut connecting several wires together. That’s a common way of wiring receptacles. So then you have to undo the wire nut, separate the wires, and test them as Crafter Man said.
They’re kind of 2 different things:
So the best protection is a 3-wire grounded circuit, AND a GFCI control on the circuit (either a GFCI receptacle or a GFCI breaker on the circuit).
Note that a GFCI breaker will provide GFCI protection to all the receptacles on that circuit. That may be cheaper than replacing several receptacles with GFCI receptacles. But, as others have pointed out, you may not need GFCI protection for this TV. If the TV is grounded only to improve reception, only a physical earth ground will accomplish that.
???
Ground wires are so that touchable structures like your washing machine, stove, or old fashioned drill can’t go live without blowing a fuse. “Touchable” is loosely defined to include something that you might touch if the case is cracked.
So if you put a GFCI in, but there is still no actual ground, what exactly does happen if a ‘touchable’ surface goes live?
The surface will become hot, but the breaker won’t blow if there’s no ground prong attached.
Then if you touch the surface, and are touching something else that is grounded, you *will *be shocked.
If the GFCI circuitry doesn’t malfunction, it’ll cut the power and save you - but you’ll still get a brief shock.
Also, yes, certain common circuit topologies - like surge protectors - use the ground. The engineers who designed them expected it to be there.
As I feared, I’m now more confused than ever.
Wouldn’t an ungrounded circuit still trip the breaker in the event of a short circuit even without a ground wire? Isn’t that the purpose of a breaker?
mmm
I am a bit confused with this as well.
It is my understanding a ground wire is (primarily) used to connect a device’s metal chassis to earth ground.
The reason is as follows:
Let’s say a device w/ metal chassis has a two-wire power cord (hot and neutral only - no ground). The chassis is not electrically connected to anything - it is floating.
A insulator inside the device fails. Instead of there being 1 X 10[sup]12[/sup] Ω between hot and the chassis, there is now 100 Ω between hot and the chassis.
The device is in the kitchen. Mary walks up to the device and touches it. She does not get shocked because she is not grounded (i.e., she is not also touching a metal object that is electrically connected to earth ground).
Bill walks up to the device and touches it with his left hand. His right hand is touching the kitchen sink. Bill receives a shock. Why? Because the current flows from the hot, through the 100 Ω of failed insulation, to the chassis, through Bill, through the sink, and back to the circuit breaker box through ground connections.
If the device’s chassis had been connected to earth ground, Bill would not have received a shock.
A slightly different result would occur if, instead of 100 Ω between failed insulation and the chassis inside the device, a hot wire inside the device came in direct contact with the chassis (i.e. the hot shorts to the chassis). In this case, the circuit breaker would trip right away.
So to recap, there are two cases where connecting the device’s chassis to earth ground renders it safe:
Low resistance between hot and chassis inside device. The circuit breaker won’t trip, but a person (who is also grounded) won’t be shocked if they touch the chassis.
Short between hot and chassis inside device. The circuit breaker will trip, making everything safe.
And lastly, connecting the chassis to earth ground is not really the most important thing. The most important thing is to connect the chassis to the neutral/ground bus bars back at the circuit breaker panel. (If you were to simply connect a wire between the chassis and the dirt outside your house, it probably won’t work.) It’s just a lot easier to say “connecting the chassis to earth ground” vs. “connect the chassis to the neutral/ground bus bars back at the circuit breaker panel.”
So my post above shows why a device’s metal chassis is (almost always) connected to earth ground.
As a followup, let’s see what happens when you connect a device w/ three-wire power cable (hot-neutral-ground) to a GFCI receptacle. Let’s also assume the third (ground) wire in the power cable is connected to the device’s chassis.
Case 1: The GFCI receptacle has a ground wire connected to it inside the receptacle box
A. An insulator inside the device fails. Instead of there being 1 X 10[sup]12[/sup] Ω between hot and the chassis, there is now 100 Ω between hot and the chassis. The GFCI trips. Why? Because it senses an abnormally-large difference in current between the hot and the neutral. (And this is true… current is going from the hot, through the 100 Ω between hot and the chassis, through the chassis, through the ground wire, and back to the circuit breaker panel.)
B. A hot wire inside the device comes in direct contact with the chassis. The circuit breaker trips right away.
Case 2: The GFCI receptacle does not have a ground wire connected to it inside the receptacle box
A. An insulator inside the device fails. Instead of there being 1 X 10[sup]12[/sup] Ω between hot and the chassis, there is now 100 Ω between hot and the chassis.
The device is in the kitchen. Mary walks up to the device and touches it. She does not get shocked because she is not grounded.
Bill walks up to the device and touches it with his left hand. His right hand is touching the kitchen sink. The GFCI trips. Why? Because it senses an abnormally-large difference in current between the hot and the neutral.
B. A hot wire inside the device comes in direct contact with the chassis.
The device is in the kitchen. Mary walks up to the device and touches it. She does not get shocked because she is not grounded.
Bill walks up to the device and touches it with his left hand. His right hand is touching the kitchen sink. The GFCI trips. Why? Because it senses an abnormally-large difference in current between the hot and the neutral.
Of the two, Case 1 is better than Case 2. But Case 2 still offers a degree of protection.
A circuit breaker trips when there is a large amount of current on the hot wire. The two most common scenarios are as follows:
Direct short between hot and neutral. This can occur pretty much anywhere, e.g. in the Romex behind the walls of your house, inside a receptacle box, in a connector, in a power cord, in a device.
Direct short between hot and a ground wire that goes back to the circuit breaker panel. Like #1, this can occur pretty much anywhere, including a hot wire inside a device that makes direct contact with the device’s chassis (which is connected to ground).
As mentioned, a circuit breaker trips when there is a large amount of current on the hot wire. Which also means there is a large amount of current on a neutral or ground wire. A large amount of current on a wire is a bad thing. For one thing, the insulation will melt and burn, which could cause other things around it to burn. Secondly, melting insulation could cause intermittent shoring between hot and neutral wires that are next to each other (and between hot and ground wires that are next to each other) resulting in sputtering arcs, and arcing can also cause a fire. In other words, circuit breakers prevent the wiring from overheating which could cause your house to burn down.
A circuit breaker doesn’t protect you directly (like a GFCI), it protects you indirectly by keeping your house from burning down. In addition, it often protects a device that contains a short, but there are situations will it will not. It is for building protection, not direct protection of you and devices plugged into receptacles.
This was my original impression.
What is the era and type of the wiring? My house was wired a long time ago with armored cable running from the receptacles and switches to conduit. Outlets were two prong yet via the steel armor, the steel box itself was grounded. I’ve just had to replace the non-polarized two prong with three and a pigtail as needed. The mains were changed about 10 years before we moved in and whoever wired it neglected to bond the conduit to the ground bar. I needed to take care of that first.