SunshineHarvey7

Hi guys, I have a video camera that has a non-grounded power adapter, and whenever I connect the a/c adapter, it's easy to get shocked by the chassis, which measures around 80 volts (between me and the camera when I have bare feet standing on a concrete floor). I get at least 40-60+ volts on my Macbook chassis. All this is not new and strange to us who have lived in Thailand for a while. However, a friend has a video studio here in Thailand, and he does NOT want the video staff to get shocked when they touch the camera. So ... is there any way that a building can be wired so that this issue is eliminated? My friend said, "We don't have this problem in America, so I see no reason we should have it here. I want to do whatever it takes to fix the problem." He doesn't want to hear me tell him, "That's just the way it is here." I'd like to help him, but is there really anything I can do other than insisting that all cameras, laptops, and other devices must have a ground wire attached? I'm sure this question might have already had a thorough discussion, and you are welcome to share a link of such a discussion with me if you have one.

I appreciate your taking the time to share a bit of the theory. I observed that the three-phase master breaker has no provision to shut off the neutral (cut the link between the incoming neutral/ground bus bar and the neutral bus bar per your illustration). Regarding the location of the incoming neutral line (where it first lands), that was based on my uneducated guess. Sorry for raising an alarm before I have a chance to ask the electrician. (There are so many heavy wires that look similar that I can't be absolutely sure which one it is without asking the electrician.) Thus, it is possible that the incoming neutral is exactly where it is supposed to be. I'll update you when I find out. Can you please explain what an "open incoming neutral" is?

Hopefully I can have our electrician come out and show me for sure which cable is the incoming neutral and which is the ground wire. You may not hear much from me for a week or so, but don’t worry…. I’m not planning any crazy electrical experiments! ????

I circled where I think it is in yellow in the upper left corner.

If the voltage at the second ground rod is around 2-5 volts, and if the current going to that rod is 0.25 amps, then I suppose the power being dissipated to the second ground rod would be 0.5 to 1.25 watts. I have no complaints about that. However, if the total current passing from the neutral buss to the ground buss is around 7 amps (as I noted above), makes me think the total power being dissipated is around 7 amps x 2-5 volts = 14-35 watts. (Not such a laughing matter.) Another bit of info: Seems that one of the closest power polls to our office has a large steel cable passing from the neutral line at the top of the poll down to the ground. If the leakage we are getting is coming from outside our office (from "dirty power" thanks to someone else on our line), I'd be tempted to soak the ground near that steel cable to see if it would make a better "ground."

Here is a photo and video. Note in the photo that the ground buss is on the right, and the neutral buss is on the left, and the large wire that binds them together goes around the bottom of the panel. 1301968745_electricalpanel.MP4

A short video of the panel is attached. My plan next week when I return is to go to the office when no other workers are there, cut the main breaker, and then check the current between the neutral and ground busses. We actually haven’t TWO ground rods connected in series. (1) was installed at the time of construction, and the top was just under the surface of the sidewalk around the back of the building. That part of the building is sitting on about 1.x meters of fill dirt, so I recently requested that a second rod be installed in parent soil not far away. I have measured a small current (less than 0.25 amps) between the fire and second rod. I have yet to positively identify the cable that goes to the first rod, so I haven’t measured total current on the main ground wire. IMG_7505.MOV

Sorry to stress you guys. I appreciate your concern. No worries—I posted the questions just before a two-day road trip. Didn’t have a chance to read your replies until now. i won’t claim I would never do anything “stupid,” but I did read somewhere about the danger of lifting the ground wire, so I won’t be trying that! Will try to respond to other questions separately….

I’m working in a newly constructed office that has 3-phase power. I have a few questions based on my measurements: 1) In the main breaker panel, there is a large wire that ties the neutral buss to the ground buss. What might cause a current of around 7 amps to flow through that wire (according to my clamp-on meter)? 2) Is it true that a significantly unbalanced load can result in a significant leakage to ground? 3) Does it seem crazy to stick one probe of a digital voltmeter into the soil and with the other probe touch the ground rod and measure 4-5 volts or more? After I soaked the too few inches of soil, the voltage dropped to around 2 volts. Some insist it should be even closer to 0 volts. What would you say? 4) Have you had good experience with copper plated rods? Or would you insist on solid copper?

Thanks everyone for your input. The Wikipedia article seemed quite helpful.

I'm doing some research on grounding. Can someone please give me the definition of TT? And TT-S-C? (I think I read these acronyms on an electrical forum but haven't found a definition.)