Old house, open grounds?

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  #1  
Old 07-01-05, 03:44 PM
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Old house, open grounds?

I have an 80 year old house in Southern California. I was checking the circuits with a 3 prong orange plug-in device that has a series of lights that show the condition of the circuit. I found an open ground on all of the circuits I checked.

I'm trying to get a sense of what this means, specifically, and what I should do about it. I looked at the main circuit box, outdoors, and didn't see any sign of a grounding rod. The circuits seem to be two wire (black andwhite) and some are inside galvanized pipe (inside the ceiling, under the floors), some (in the basement) are under the floor joists on insulators but not in any pipes. It's all 120v although I do want to add a 240v outlet for an air compressor.

I think I would start with a grounding rod...is there a particular type of metal I should use, and how far into the ground would it go. Would I attach it to the metal of the circuit box or to the ground bar, or where? What size wire?

There is an off/on box before the main circuit box so I can disconnect the electricity before I do any work.

I'll be glad to hear any suggestions.

John
 
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Old 07-02-05, 05:30 AM
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The 'open ground' indication on the tester will always occur on 2 prong wall outlets. Your 2 wire household wiring would need to be replaced with modern 2 wire/with ground (thus 3 wire) circuits. Adding a ground rod will do nothing toward that end.
 
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Old 07-02-05, 07:15 AM
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John,

As stated simply driving a ground rod will not solve your problem and I venture to say the house water supply is not grounded either or is on cistern....as if it is a pulic water supply and is metal pipe entering the residence it would need to be bonded to the grounding system also. As for adding the 240V plug for an Air Compressor....first you need to consider if the house panel can handle that as homes 70 years ago were not wired to handle applicances and things like this.

The wiring you are refering to is probably done in 2 stages.....the Gav. Pipe at one point probably in the late 40's and the open wiring probably before that. I venture to say the open wire on insulators is Knob and Tube...but who knows.......

Anyway....I personally would place the air compressor on a back burner and venture the thought of brining the wiring up to modern requirements or atleast a service change to get the system up to date as best you can for the new circuit you wish to add and other future additions as I expect you only have maybe 1 or 2 recepts per room and less than 5 circuits in the whole panel that you currently have....
 
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Old 07-02-05, 05:46 PM
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If you have three prong receptacles in your residence then you have a code violation. It is (and always has been, as far as I know) against code to simply install three prong receptacles if the circuits are not grounded.

What should have been done in this case would have been to install new wires, add ground wires to the circuits, or install GFCI protection to the circuits, or simply install old style 2 prong receptacles.
 
  #5  
Old 07-03-05, 03:13 PM
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Thanks for straightening me out on this. You're right, electricalman, not too many outlets or circuits in the house...although it is a small house. And there are two cisterns which collected rain water from the roof originally.

Any new outlets added I was going to do on new circuits, using 3 wire Romex. Can you tell me if Romex needs to go through conduit, and if it is an extra safety factor to use outdoor Romex indoors (or just a waste of money?).

There are two service (?...may be using the wrong names) boxes outside. The first which has a handle and is used to shut off the electricity, is old and has two screw in fuzes. The second, connected to the first, has breakers and room to add some more breakers. For the 240v circuit I was going to add 2 more breakers and run the lines to an outlet, that's how I have the compressor set up where I live now.

I'd like to ground the public water supply, is there a preferred way? Also, to add a larger service box would I piggyback it onto the old one or replace the old one.

John
 
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Old 07-05-05, 09:29 PM
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Originally Posted by jbclem
Any new outlets added I was going to do on new circuits, using 3 wire Romex. Can you tell me if Romex needs to go through conduit, and if it is an extra safety factor to use outdoor Romex indoors (or just a waste of money?).
Much of it will depend on local code; typically romex does not need to go through conduit unless it passes through living space. And there is no advantage to using the outdoor romex indoors; it would be, as you suggest, a waste of money.

For the 240v circuit I was going to add 2 more breakers and run the lines to an outlet, that's how I have the compressor set up where I live now.
Don't use 2 separate breakers to get 240v unless you join them so they trip together. If one would trip independently of the other you wouldn't like the result.

Also, to add a larger service box would I piggyback it onto the old one or replace the old one.
I'd put the new box first; run the old service off a breaker in the new box (you'll have to check the fuses in the old disconnect box to determine what size breaker to run it on). Also run any new circuits off the new box. As you upgrade your current wiring, move those circuits to the new box until the old box is no longer needed.

Keep in mind that if you increase the size of your service, you may need to upgrade other items such as the meter base and service entrance cable.
 
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