I'm in Wisconsin, you're in California, so there's not much I can do as far as inspecting, but I am a licensed PE with my specialty in power systems. We perform ground resistance testing on a regular basis, pretty basic and mundane test, really. Our primary service is testing and verifying installations by contractors, especially in systems they don't understand well. Electrical inspectors come to us when they have questions.
A picture is worth a thousand words. Pull your panel cover if you feel you can do this safely, and take some good pictures. This is basic stuff, I can at least tell you if you have a problem.. then get the electrician involved from there.
A picture is worth a thousand words. Pull your panel cover if you feel you can do this safely, and take some good pictures. This is basic stuff, I can at least tell you if you have a problem.. then get the electrician involved from there.
I just can't believe you don't have a ground...
You mentioned a slab at one point. I wonder if you have a slab ground, also known as a "ufer" ground, which is an earth ground connection embedded in the slab. When I have installed these, they are 2 pieces of rebar sticking up into the wall space. There is a clamp used to connect the ground wire to the ufer ground posts. Your ground wire may have been somehow routed in with the service entrance.
BTW, an underground service entrance conduit and ground is also installed by the utility customer (electrician wiring the house). Part of the trench is often dug by the electrician also. The utility company lays the wire in the ditch, pushes it up the conduit, and makes the connection to the meter.
The ground wire does not usually go in the service entrance conduit, though. The actual routing of the ground wire depends on the type of ground and type of meter base (actually a meter box these days...) I suppose there's nothing in the code that says the ground wire can't go in the conduit with the utility service entrance conductors... I know the utilities I worked with didn't want anything else in the conduit.
I think a photo of the neutral and ground buss bars in the panel would probably tell the story but I wouldn't ask anyone to open their electrical boxes.
Michael
You mentioned a slab at one point. I wonder if you have a slab ground, also known as a "ufer" ground, which is an earth ground connection embedded in the slab. When I have installed these, they are 2 pieces of rebar sticking up into the wall space. There is a clamp used to connect the ground wire to the ufer ground posts. Your ground wire may have been somehow routed in with the service entrance.
BTW, an underground service entrance conduit and ground is also installed by the utility customer (electrician wiring the house). Part of the trench is often dug by the electrician also. The utility company lays the wire in the ditch, pushes it up the conduit, and makes the connection to the meter.
The ground wire does not usually go in the service entrance conduit, though. The actual routing of the ground wire depends on the type of ground and type of meter base (actually a meter box these days...) I suppose there's nothing in the code that says the ground wire can't go in the conduit with the utility service entrance conductors... I know the utilities I worked with didn't want anything else in the conduit.
I think a photo of the neutral and ground buss bars in the panel would probably tell the story but I wouldn't ask anyone to open their electrical boxes.
Michael
This thread is a case for IEEE to wrap up and someone qualified in proper installation work to give advice. There's far too much heresay. Anyone opening a distribution box must be for a very good reason. There are alot of old installations about which often used the neutral and earth together, i.e two wire, but really in this day and age these problems are diminishing. It seems by the posts the US lacks proper installation knowhow and inforcement, totally opposite to that in Europe. I wonder how many meter readings are actually correct ?
That's what's happening, but I won't force myself into the issue. If he doesn't want advice, he doesn't have to take it.
The box is already open, or has been. This is about the best reason I can think of to perform an inspection.
A well-informed position, no doubt.
Hi,
It is possible to buy an isolated autotransformer!
I am using one at work to measure leakage currents.
Before using it, I performed many tests and measurements to ensure the beast was really, really isolated. It is. I was surprised as I thought these things did not exist.
Variable Transformers
If in doubt, do NOT use them. Play safe.
Cheers,
Serge
It is possible to buy an isolated autotransformer!
I am using one at work to measure leakage currents.
Before using it, I performed many tests and measurements to ensure the beast was really, really isolated. It is. I was surprised as I thought these things did not exist.
Variable Transformers
If in doubt, do NOT use them. Play safe.
Cheers,
Serge
Technically speaking, that is not an autotransformer, and does not provide the #1 benefit of an autoxfmr: minimal core size for a given transformation ratio, thus minimal cost.
A true auto has a shared primary and secondary winding. But functionally, yes, that variac you linked to (which is a combination isolation transformer with an autoxfmr secondary) will do the trick.
Neither core size nor price is minimized with this design, unfortunately.
A true auto has a shared primary and secondary winding. But functionally, yes, that variac you linked to (which is a combination isolation transformer with an autoxfmr secondary) will do the trick.
Neither core size nor price is minimized with this design, unfortunately.
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