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Electrical socket not properly grounded?

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#1 of 5 OFFLINE   Phil Carter

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Posted August 09 2003 - 07:20 PM

Hey folks,

Bought a Monster Power surge protector to watch over my new HT equipment, as I'm not keen on having one of the frequent Atlanta-area thunderstorms fry my new stuff. It has an LED that's labeled "Ground OK" which, I presume, verifies that the electrical outlet it's plugged into is properly grounded.

The problem: The outlet I want to use for the TV and the rest of the HT gadgetry is not giving me a little green light for "Ground OK". I tested it on other outlets and the "Ground OK" light glows on those, but not on this outlet.

Now, I live in an apartment complex, so if there's an electrical issue here they had better fix it for me. However, I know nothing about electrical stuff / impedance / grounding, etc. Can somebody tell me in English what to tell the complex manager so that this can be taken care of properly? Or, if I'm not going to harm my equipment by using this outlet, let me know that too. Posted Image

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#2 of 5 OFFLINE   Allan Jayne

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Posted August 09 2003 - 11:54 PM

In a properly constructed home power system, one of the two conductors is grounded. But, due to idiosyncrasies in the way connections are made can cause unreliability, which is probably one of the reasons that building codes require a third continuous ground conductor and three prong outlets.

Older homes do not have to comply with the latest electrical codes which require a proven (sometimes called bonded) ground from every outlet which must be for three prong plugs, if the older outlets were already there. But when new circuits are installed, they must comply.

Meanwhile older circuits, even though they pass the ground test, may still have a ground that is not reliable for power surge purposes. This is due to loose or corroded connections where the ground is not a wire but rather the gooseneck like metal sheath around the cable (BX cable) screwed onto the metal boxes in the wall at each outlet.

You can get a three prong to two prong adapter, fasten a 12 gauge wire to the spade lug that protrudes, and run this wire to a known ground such as a metal water pipe or the screw that holds the cover on an outlet that passes the ground test.

Video hints:

#3 of 5 OFFLINE   Wayne A. Pflughaupt

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Posted August 10 2003 - 12:23 PM

Phil, It would probably be best to study one of those ‘”picture books” on residential electrical at a hardware store to get a visual for this. Basically, there should be at least three wires attached to every outlet. The ground wire is typically bare, with no insulation on it. It should wrap around a screw at the bottom of the outlet. If the ground light on the Monster power strip is not lighting, that means there is no ground connection present. This can mean that the outlet itself is physically damaged, or the ground wire is not connected. The tricky part: Since there are multiple outlets on a circuit, the romex (trade name for the type of cable used in most residential wiring) is “daisy chained” – i.e., it goes from the breaker panel to the first outlet. A second romex cable is also attached to the first outlet and routes to the next outlet. The last outlet in the circuit will have only one cable connected to it. Thus, if say, there is a problem with the ground connection at say, the second outlet, it may carry on to the rest of the outlets behind it. In other words, of you pull the problem outlet from the wall and it appears to be in good shape with all connections solid, the connection may have been “lost” at another outlet in the circuit. Regards, Wayne A. Pflughaupt
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#4 of 5 OFFLINE   Phil Carter

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Posted August 10 2003 - 12:33 PM

Wayne and Allan:

Thanks for the comments. They do mostly go over my head, but the complex has promised they will take a look tomorrow. I don't dare mess around inside electrical sockets myself for fear of becoming post-toasty-roastied, so unfortunately Wayne's suggestion to pull the outlet and have a look isn't really viable for me. Even if I were to kill all the circuit breakers, I would somehow manage to zap myself anyway. Posted Image

The odd thing is that the problem outlet is on the other side of the wall from the circuit breaker panel (the wall divides my kitchen from my living room), so it seems to me that it must be the first, or near the first, in the daisy chain you mentioned. I am able to get a good ground in all the other outlets in the house, oddly enough.

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#5 of 5 OFFLINE   Steve>Smoker



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Posted August 10 2003 - 01:30 PM

Domestic supply should usually have 3 connections. A live or feed, a neutral or return and an earth or ground. The two flat pins are live and neutral, the big round pin is the ground. The neutral does eventually go to ground, but only wayyyyy back up the supply line at the mains transformer. Thats why the PD or voltage between the neutral and ground should be 0v. All your looking for is continuity between the socket ground your plugging the Monster strip into and something like a metal water or gas pipe. By law all domestic pipes have to be bonded to earth to prevent them becoming live under fault conditions and zapping someone. In theory all the sockets should have a ground but older buildings and badly installed wiring wont have the grounds linked up. If you have anything to test continuity (basically resistance) stick one probe on the sockets round pin-hole and one end on a water pipe. If you have a ground connection it'll read 0 resistance or short, if not youll prolly get a reading of 'infinity' or an open circuit. Hope I'm not too confusing .....

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