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boddah 01-19-2008 05:21 PM

grounding outlets
 
I have some outlets in my home that are not grounded. Can a gfi act as a ground in these areas?

chris75 01-19-2008 05:26 PM

Quote:

Originally Posted by boddah (Post 89999)
I have some outlets in my home that are not grounded. Can a gfi act as a ground in these areas?

They dont act like a ground, but they are the next best thing... and it is allowed by code to replace 2 wire receptacles with gfi protected ones.

boddah 01-19-2008 05:30 PM

I will be connecting a surge protector, for my new tv, to this outlet. Will this way protect my tv?

chris75 01-19-2008 05:33 PM

Quote:

Originally Posted by boddah (Post 90004)
I will be connecting a surge protector, for my new tv, to this outlet. Will this way protect my tv?

protect it from what?

boddah 01-19-2008 05:39 PM

power surges , lightning storms

chris75 01-19-2008 06:03 PM

Quote:

Originally Posted by boddah (Post 90007)
power surges , lightning storms

Forget about lightning, the only thing that will save it is if you unplug it, along with catv or satellite connections as well....

I don't believe power surges shunt the surge to ground, it just would not make sense... but I didnt invent a power surge either... so maybe someone with the right background can answer that part of the question.

J. V. 01-20-2008 11:27 AM

Chris is so correct on lightning. Nothing can stop it, Nothing. Unplugging is the only way to be certain. Turning off the power strip is not good enough either. Even with the power off, the satelite, cable or antenna is a perfect path to destruction.
Install the GFCI as instructed. If you have an antenna or satelite make sure they are grounded to the main grounding rod or another grounding means.

jwhite 01-20-2008 12:31 PM

Quote:

Originally Posted by boddah (Post 90004)
I will be connecting a surge protector, for my new tv, to this outlet. Will this way protect my tv?

Most surge protectors are useless if not conected to a ground.

Stubbie 01-20-2008 01:56 PM

Yep, any surge "suppressor" with MOV technology which is the case with most middle priced to low priced suppressors shunt the transient voltage to ground, they certainly don't magically absorb the surge. Semiconductors like Metal Oxide Varistors (MOV) act like gates with two outlets dependent on voltage levels. High voltage causes an instant low resistance in the MOV opening the gate to ground to divert the higher voltage. This all happens in a nano-second or less. Expect to pay between 50 and 150 dollars for surge suppression that is worth having. Be sure to read the UL label on the surge suppressor to see what it is capable of handling as far as voltage surges. They will add protection from both lightning and utility and inside the home surges. Direct lightning strikes to the utility coming into your home are only controlled by utility installed protection systems which will actually disconnect power till the surge has dissipated. These are not that common in residential developments. A direct strike to your home is pretty much impossible to completely control the massive levels of current and voltage.
However a good surge suppressor is darn well needed just the same. Make sure you get one that will allow connection of all cable types you may have in your entertainment system and also phone and computer. Buy a good one or you will be wasting your money anything under probably 50 or 60 bucks is not worth having to protect good equipment. High end surge protection is 3 to 4 hundred dollars.
Now having said all that you need to bone up on surge protection as it is easy to NOT get what you think you are paying for so use the internet to learn what to look for in a surge suppressor.
One critical thing to watch out for is suppressors that "save themselves" from a long lasting surge. These suppressors disconnect themselves from the power surge so they don't get damaged but your equipment will get fried. Thats how they keep from having to honor the warranty they offer. Nothing wrong with the suppressor so hey your equipment damage couldn't have been damaged from surge. Good suppressors continue to operate for the entire surge period difference is your not going to have damage to your equipment so the warranty is based on your getting a faulty suppressor. Point is warranty on this type of protection is very difficult to enforce so get a good product.

Genettos 01-20-2008 06:36 PM

Some points to ponder:

Inside a residence a voltage surge can occur between either of the two hot legs and neutral, or between the two hot legs. This is known as “normal mode”. Also, inside a residence a voltage surge can occur between either of the two hot legs and the EGC (safety ground), or the neutral to the ECG. This is known as “common mode”.

External to the residence, before the neutral/EGC bond, the EGC does not exist. Therefore a “common mode” voltage surge cannot exist. A lightning strike on the power distribution system or a distribution system component failure can result in a “normal mode” voltage surge at the residence’s service entrance. The main breaker panel provides a direct connection and thus a very low impedance path to all branch circuits for “normal mode” surges. Due to, primarily, capacitive coupling some of the energy of the surge will couple to the ECG and produce a “common mode” surge. Since the coupling impedance is higher than the direct connection, for lower frequencies the common mode surge will have less damaging energy available than would the normal mode surge.

Inside the home, there are only a few appliances whose failure could produce high voltage surges but none could produce energies comparable to external sources. Their failure would likely produce a “common mode” surge rather than the “normal mode” surge.

Of course in older homes lacking the “safety grounding wire”, a common mode surge of any damaging energy content cannot exist.

A surge suppressor must protect against normal mode and common mode surges. The design purpose of a surge suppressor is not to shunt current to ground, although that may occur. The design purpose is to short two or all four wires together (hot legs, neutral, and ground). If the wires are shorted, no surge voltage can exist between them. Unfortunately the desirable 120/240vac potential would also be shorted and the circuit breakers would trip. The design can use a device such as a MOV to provide a short circuit at voltages higher than the peak value of normal residential voltage. A very high current will flow through the MOV so it must be constructed to survive long enough to short the wires together during the duration of the surge.



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