Grounding Outlets


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Old 01-02-06, 09:35 AM
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Our old house has a mixture of grounded and ungrounded recepticals. I used one of those three light plug testers and it indicated that all of the 3 prong recepticals were grounded. Is it safe to assume that these recepticals are properly grounded?

Thanks,
Brian
 
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Old 01-02-06, 09:50 AM
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Brian,

I split this to a new thread, since it takes the original topic in somewhat of a new direction.

You cannot assume anything when you have a mix of grounded and ungrounded receptacles. I suggest that, with the power off, you open the boxes containing these three prong receptacles and examine the wiring. Post back with what you find.
 
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Old 01-04-06, 09:47 PM
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Well, I had a little time to check into this tonight.

In this particular room, there are 4 recepticals, 2 of which are "grounded" to of which are not.

Anyway, the two that are grounded appear to have cables that have a black, white and a bare wire. The two that are not grounded, have two braided fabric wrapped wires coming into the box, no ground.

I guess the next step is to see if I can tell if the grounded wires go all the way back to the box.

Most all of the recepticals in the house are three prong, but a majority of them are ungrounded.

I will see if I can get some pictures posted later.

Brian
 
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Old 01-05-06, 04:42 AM
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The ungrounded three prong receptacles are a code violation, unless they are GFCI protected.

Receptacles that are three prong either need to be properly grounded, or need to be GFCI protected. You should replace these with two prong receptacles or properly ground them, or provide GFCI protection.
 
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Old 01-05-06, 11:28 AM
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That is what I was afraid of. I'm sure that there are plenty of other code violations in the house to go along with it.

I don't think that those circuits are GFCI protected. It would probably be less work to find the beginning of the circuit and replace it with a GFCI than to replace all of the recepticals with 2 prong. I need to evaluate the situation a little closer.

If I leave the circuit ungrounded and used one of the two methods listed above, is it still a hazardous situation? Would it be better to just bite the bullet an pursue upgrading the wiring?

Thanks,
Brian
 
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Old 01-05-06, 11:44 AM
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Leaving a three prong receptacle with an open ground is only unsafe if someone uses a three prong device in the receptacle. Using a two prong device is just as safe if the receptacle is grounded or not. The danger is that someone might think the receptacle is grounded and that they would have the protection that a grounded receptacle offers when they really don’t.

Providing GFCI protection means that any ground fault will cause the GFCI to trip. This is considered safe because the GFCI will trip before enough current travels through the body to cause injury. However, the receptacle is still ungrounded, and anything that needs a ground (surge suppressors, computers and other electronic equipment, etc.) would not have a ground.

Switching the receptacles out for two prong ones is perfectly safe because it’s obvious that the receptacle is not grounded (or at least that it might not be grounded).
 
 

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