wiring into home grounded?

ready2movesSeptember 16, 2013

A friend of mine is interested in buying an older home, but the wiring in part of the house has the outlets with the grounding (meaning 3 plug) and part of the house does not have this, just outlets for 2-prong plugs.
Without hiring an electrician, can someone explain to me why the difference in the outlets?
Logically, you would thing the entire house would have outlets with 3-prongs.
any help for them???
thanks

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Ron Natalie

The third (ground) pin is a dedicated conductor back to the grounding electrode system. It is there to provide a low impedence path back to ground (one leg of the receptacle is already grounded, but it carries current and can be displaced in potential from the actual ground).

There are two ways to "fix" a two way circuit. Either replace the wiring such that it adds the third grounded wire ***OR*** protect the circuit with a GFCI.

    Bookmark   September 16, 2013 at 10:20PM
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ionized_gw

The house was certainly built when grounded outlets were not required, or maybe, not available. The owners added some grounded outlets when they needed more outlets (New work must meet current building codes.) or needed a grounded outlet. There is no real reason to have a grounded outlet to plug in devices with only two prong plugs so you can do things piecemeal, when you need them

If you want to plug in stuff with three prong plugs, you need new cable back to the circuit breaker or fuse. Adding GFCI, without ground, might be a good idea where those are now required, wet areas. A GFCI does not provide a proper ground for things that need it and these things have three-prong plugs on them.

    Bookmark   September 17, 2013 at 3:12PM
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ready2moves

Guess I need to clarify:
original house built with 3-prong outlets in washroom, bathrooms, and kitchen and utility, but the rest of the house has only outlets with 2-prongs.
What possible buyers are wondering is if the electrical needs to be updated which is an additional expense. The original owners of the house now, have lamps, etc all plugged in the 2-prong only rooms just fine.
I am not sure they would need to update the wiring, since where 3-prong is needed, it was there originally.
clearer?

    Bookmark   September 17, 2013 at 4:15PM
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jreagan_gw

How old is the house? There is another possibility going on... In the past, you could use armored BX metal jackets as the equipment ground. Do you know if that is being used?

These days, you wouldn't do that. The steel in the BX isn't the best conductor and all you need is one break in the box-to-box connections and you lose the equipment ground.

    Bookmark   September 17, 2013 at 4:21PM
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jreagan_gw

To answer the question, do they NEED to have it upgraded? No, I don't think so. If he wants, he can get a licensed electrician in addition to the home inspector to examine the house. Depending on the age, there may be other risk factors that would impact the purchase price (ie, like knob & tube connectors or decayed insulation). Are there circuit breakers or screw-in fuses?

    Bookmark   September 17, 2013 at 4:27PM
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ionized_gw

It is quite possible that the rest of the junction boxes with the outlets in them have grounds run to them. That would be good to know so when it comes time to do the inspection, go with your friend and take off all the covers to look.

    Bookmark   September 17, 2013 at 7:08PM
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Ron Natalie

If you want to plug in stuff with three prong plugs, you need new cable back to the circuit breaker or fuse. Adding GFCI, without ground, might be a good idea where those are now required, wet areas. A GFCI does not provide a proper ground for things that need it and these things have three-prong plugs on them.

First off, "wet areas" doesn't really define the areas needed to be protected by GFCI.

A GFCI doesn't provide a ground, but it will protect the operator from fault currents that would have been carried off through the ground if it were present and hence is a LEGAL and SAFE way to use three prong devices. About the only thing that loses in this regard are certain surge protector device that really wanted to sink current to ground.

If you do this there's a requirement to mark the receptacles as not having an equipment ground.

    Bookmark   September 17, 2013 at 8:45PM
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