Grounding old house?


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Old 05-13-09, 03:45 PM
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Grounding old house?

Just moved into a 1957 house, there are no grounds at the circuit panel, the wire is "non-metallic 14/2 600v". The panel is using 20A breakers with this wire. Shouldn't they be 15A?

I've read a lot of good info here on grounding. I don't think I want to pull a lot of wire so the suggestion for a GFI at the beginning of the circuit, or maybe the suggestion of a GFI breaker in the panel box sound like solutions that I can live with.

I will be running several computers on one circuit, these computers will have UPS's. I've read some comments that say that computers, tv's, etc have to be grounded to protect sensitive components. Does this mean that a GFI breaker will not be an adequate solution?

Measuring voltage in a couple of wall receptacles between black & metal box gives me 21v. White to box is 0.4v. Using Fluke meter. What could be causing this 21v 'leakage'? I haven't yet mapped the circuits but I checked several at locations that I would assume are on different breakers and still get this 'leakage'.

Jon
 
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Old 05-13-09, 04:49 PM
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#14 should be on a 15 amp breaker. GFCIs don't provide grounding.Best to run a new circuit using #12 and one of the 20 amp breakers you need to replace as soon as possible.

Edit: Remove incorrect response due to misreading post.
 

Last edited by ray2047; 05-13-09 at 06:59 PM.
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Old 05-13-09, 05:08 PM
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The 21v you are seeing sounds like you are not getting a proper ground. If you don't have a ground wire at the receptacle then it isn't possible to use the metal box as a ground for checking voltage (in a wood built home). Read between the white/neutral wire and the hot/black wire. If you don't have any grounds in your panel you may not have a ground rod. A ground rod really needs to be installed if you don't have one. The GFCI won't really serve the purpose without a properly grounded panel via ground rod.
 
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Old 05-13-09, 07:39 PM
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Thanks guys for info on GFCI & grounds.

Originally Posted by Nexxus View Post
If you don't have any grounds in your panel you may not have a ground rod. A ground rod really needs to be installed if you don't have one.
I'll have to check on the ground rod. This house has a knife switch on the outside protecting each leg of the power with a 100A blade fuse. The panel is inside in the hallway. I haven't crawled the underside of the house but from what I can see with a flashlight the power from the knife switch to the panel is in a conduit. I would presume that a rod would be on the outside, not underneath. On my prior house, built in 1940, there was no rod.

I will be having the kitchen remodeled, I guess I'll have the electrician do a ground rod at the same time if I don't locate one.

Another question: The main panel is 150A. If I were to upgrade it what size should I go up to?

Thanks, Jon
 
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Old 05-13-09, 08:15 PM
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The "21 volts" you see on your digital voltmeter when connected between the black ("hot") conductor and the metal box is a "phantom" voltage and not a true reading. Digital meters are famous (or infamous) for these phantom readings and therefore not usually the best choice for a non-professional.

I seriously doubt that your panel or main switch is not grounded. Most likely it is grounded to a metal water pipe. Also, if you have 100 ampere fuses in your main switch then you have a 100 ampere service, not 150 amperes, no matter what your panel label may state.

If you have #14 wire then you MUST protect those wires at no more than 15 amperes. I suspect that your circuit breaker panel was installed without a permit, most likely by a previous owner or his brother-in-law.
 
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Old 05-13-09, 09:32 PM
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Originally Posted by furd View Post
The "21 volts" you see on your digital voltmeter when connected between the black ("hot") conductor and the metal box is a "phantom" voltage and not a true reading. Digital meters are famous (or infamous) for these phantom readings and therefore not usually the best choice for a non-professional.
Thanks, I broke out my 30 yr old analog meter and you are correct, it shows no needle movement at the lowest VAC scale.

Originally Posted by furd View Post
I seriously doubt that your panel or main switch is not grounded. Most likely it is grounded to a metal water pipe. Also, if you have 100 ampere fuses in your main switch then you have a 100 ampere service, not 150 amperes, no matter what your panel label may state.
OK, I'll crawl under the house and check it out. Thanks for the suggestion.

Originally Posted by furd View Post
If you have #14 wire then you MUST protect those wires at no more than 15 amperes. I suspect that your circuit breaker panel was installed without a permit, most likely by a previous owner or his brother-in-law.
The panel certainly appears to be original and since I'm the 2nd owner of this 52 yr old house, built by a licensed contractor, I seriously doubt it was installed w/o a permit. However, that does not exclude the possibility that somebody may have changed out the breakers at some later time.

Looks like I have some work to do here.

Thanks for the info
jon
 
 

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