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Question for someone w/ general knowledge
#26
I sense that some of the posts are confused between the subject of electrical power grounding and electrical power surge. I will stick to grounding in this post because that is how this thread was started. I would suggest starting a new thread if someone is interested in discussing surge protection.

Electrical power grounding as addressed by building code is principally a safety issue. There are grounding issues that have to do with signal transmission and the integrity of equipment inter-connected by signal cables when the equipment are plugged into different outlets but I won't go there because that is not typically a code problem. An example could be a DSL modem in the garage or utility room connected by ethernet cable to a computer located in a home office.

The third connector in the plug is the green wire in an appliance and it is typically connected to its frame or chassis. Its purpose is to direct leakage current caused by worn out insulation on a hot wire, for instance, directly to ground instead of through the body of a person touching the appliance. Power is supplied through the hot wire and returns through the neutral so there is no functional requirement to have a ground wire in a stand alone appliance, other than safety that can be addressed by double insulation.

Some appliances are sometimes referred to as double insulated so they do not have a grounded plug. The second insulation is usually accomplished by using plastic or resin for the housing so a human body has no direct contact with a conductor when handling the appliance.

Some appliances like washing machines are just natural potential electrical safety hazards because they are made of metal and water can conduct sufficient electrical current to be lethal. This is an example of a place where an ungrounded outlet should never be used. Washing machines are also hooked up to a source of water so one solution is to use a water pipe as a connection to earth ground. Just make sure the plumbing is NOT plastic and it is worth testing to make sure it is grounded.

The subject of what constitutes a GOOD earth ground is a subject into itself so I won't go there in this post.


Larry

Larry
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Messages In This Thread
Question for someone w/ general knowledge - by Guest - 12-15-2007, 02:07 PM
RE: Question for someone w/ general knowledge - by Guest - 12-15-2007, 02:22 PM
RE: Question for someone w/ general knowledge - by Guest - 12-15-2007, 02:34 PM
RE: Question for someone w/ general knowledge - by Guest - 12-16-2007, 05:05 AM
RE: Question for someone w/ general knowledge - by Guest - 12-17-2007, 12:35 PM
RE: Question for someone w/ general knowledge - by sansei - 01-01-2008, 06:12 AM

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