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In Reply to: Question about the center plate screw posted by Mark Tinordi on April 7, 2007 at 01:01:17:
If you're using a center plate screw and a "ground adapter" it's probably because you don't have a three-prong receptacle and wish to use a device with a three prong cord end.If this is so, you have a two-prong receptacle and probably also have two-wire branch circuit wiring to that receptacle.
If THAT is so, then you have no dedicated safety ground. All you have is a hot wire, a neutral wire, a non-self-grounding 2-pole receptacle, all tucked neatly inside a metal box that is nailed to a 2x4 and adjacent to a sheet of drywall.
So where is your path to ground in all of that?
Those who decree "No worries, the neutral is grounded!" are failing to understand we're not talking about a short from hot to neutral - as this would result in a ground fault that would almost certainly open the breaker with EITHER type of receptacle EVEN with the ground pin removed. (Ground is not involved with a L-N short.) But we're talking about a short from the hot to the CASE - NOT to neutral. Neutral is grounded AT THE PANEL... NOT AT THE CASE!
It's even worse if you're in your garage and there is a metal cover plate instead of a plastic one. If you get a short to the case, your trusty little "ground adapter" is simply going to energize the metal cover plate as well. Now, if you don't get electrocuted by your appliance, you might get electrocuted trying to unplug it!!
Nobody is mentioning the best solution for this: have an electrician run at least one modern 3-pole branch circuit to the vicinity of your gear to service your 3-pole appliances. Let's face it - where are you going to have more plugs in your home than behind your TV/AV rack or audio room?
People in these threads are balking at the cost of electrical work in their homes, but talk about spending $10K on speakers.
I just don't get it.
Cheers,
PrestoP.S. If you DO for some reason have a 2-pole plug on the end of a 3-pole branch circuit (aka Romex with ground wire) that's the easiest fix of all. Simply kill the breaker, remove the 2-pole plug, and install a 3-pole plug and connect H, N and G wires to their respective terminals.
Follow Ups:
So why are they allowed to be sold at all? I don't get it.In my case, it's not that I'm running out to buy $10K speakers and neglecting the circuitry. My entire system cost about $2000 and took maybe six months to get enough extra money to afford it... I'm definitely on the far low end of the high-end spectrum. It's easy to get great stuff on a budget if you know where to look and have a little bit of patience. Doesn't mean I've got the cash to go throwing at electricians, unfortunately; call me reckless but I'll take my chances. Electrical outlets were around for almost a century before the ground pin was invented; people didn't drop like flies then, even with big power tubes being the norm. Sure it was more dangerous then, but it was hardly a catastrophe.
> > Electrical outlets were around for almost a century before the ground pin was invented; people didn't drop like flies then, even with big power tubes being the norm. Sure it was more dangerous then, but it was hardly a catastrophe. < <Depends on your definition of "catastrophe." According to the US Fire Administration, residential fires caused by electrical faults kill approx 485 Americans and injure 2,305 more every year. About 1000 Americans are killed by electric shocks every year, and many more are injured.
This death toll totals to 10 times the number of people that were killed in the Oklahoma City bombing, which was definitely a catastrophe, and is roughly equivalent to the number of people killed as a result of Hurricane Katrina.
what part of the country you live in. It is my understanding a lot of older homes in the NE were wired in BX. BX had a flexible metal armor around the two insulated conductors The metal armor is connected at the panel board and rough-in box by connectors. Problem is corrosion over the years my effect the conductivity at the box fittings.
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