Open Preview See a Problem? Details if other :. Thanks for telling us about the problem. Return to Book Page. Preview — Faulty Ground by Gabrielle Donnelly. Faulty Ground by Gabrielle Donnelly. Get A Copy. Published first published December More Details Original Title. Other Editions 2.
Friend Reviews. To see what your friends thought of this book, please sign up. To ask other readers questions about Faulty Ground , please sign up. Lists with This Book. In a few older systems, though you may find a circuit has been added on later using what is called "BX cable". This is the wiring with a spiral metal covering on the outside.
FIREFIGHTER SHOCKED DUE TO FAULTY GROUND FAULT AND CRASH TRUCK BECOMING ENERGIZED
Normally the clamps used to anchor the cable to the fuse box and to the outlet box in the room manage to establish an electrical connection between the fuse box itself and the outlet box. In that case, because the fuse box itself is supposed to be grounded, the outlet box will be, too. Today's design with 3-prong outlets etc. The color code is: Black for Hot the "supply" of power , White for Neutral for returning current and bare for Ground. When a 3-prong outlet is mounted in the wall box so that, of the triangle of slots and a hole, the round hole is at the bottom pointing down, then the round bottom one is Ground, the left one with the wider slot is Neutral, and the right one is Hot.
That way you cannot plug even a 2-prong proper "Polarized" plug in wrong, because the wider Neutral blade won't fit into the narrow Hot slot. In older non-grounded systems, there is no Ground, but there still are Hot and Neutral. However, often these sockets were made with no difference in slot widths, and there was no standardization on whether Hot was left or right. That is because the tester cannot show you very small voltages between Neutral and Ground.
In an older ungrounded system, you'll still detect VAC from Hot to Neutral, but there appears to be no voltage from either of those slots to the metal box in the wall. That is because the metal box is not connected to anything! There is no Ground available at the box. If you have a decent multi-use electrical meter with AC Volts and Resistance ranges, you can do three other tests. The first is simply to repeat those neon tester ones, setting the meter range to measure more than VAC say, Note the readings - they should look like either to VAC, or no volts. Now the second tests: for only the ones that appear to be zero volts like Left Neutral to Ground , try setting the voltmeter to even lower ranges, like VAC or VAC.
IF you also have a heavier load connected to the circuit say, a teakettle plugged into the other half of the outlet you may see small fluctuating voltages there. However, if you are testing an old system with no Ground in the box, you probably will still see no voltage just because the box is NOT connected to Ground or anything else.
Now the third test is for Continuity or Resistance. You ONLY do this on places where your previous test says there is no measurable voltage present, so maybe the two test points are actually connected together somewhere.
You set the meter to read Ohms Resistance and apply the probes to the two test points. If they are connected, you should read only a very few ohms, and you may find the reading depends on how hard you push the probes to make contact with the metal. If you think the place you are trying to test really is a Ground and want to verify that for example, the metal box mounted in the wall, or the Ground round hole in an outlet , you need a known true Ground for reference. Try hooking up a long piece of wire to a water pipe or, even better, to the real Ground terminal where your fuse box is connected to a water pipe near it.
Now measure the resistance from your test point to true Ground. It really should be no more than a few ohms, often less than one ohm and hard to measure. Now to start on solutions, other than moving or persuading the landlord to re-wire the place. For the purposes of getting rid of low-level voltages, either static charges or electrical noise signals, you can try to connect a separate green wire from the computer outside case to a reliable Ground. Best place to look is a water pipe. Water supply systems run a pipe though a lot of soil, thus providing good electrical contact to the earth.
Older systems are ALL metal piping, so it works. However, some have been modified with plastic piping components in odd places, so it is always possible that a water tap may NOT be a reliable Ground, and it is nearly impossible for an amateur to tell. But that's still your best bet. See item 5 above on how to test and verify whether a possible Ground point near your computer really is Grounded to the earth. The other function of a good Ground is in electrical supply system safety.
One way a Grounded system protects you is that any part of your appliance that is exposed to people should be connected to true Ground. Then if anything goes wrong in the appliance and the Hot supply comes into contact with that exterior, the Ground lead does two things. The most important is that it provides a high-current-capacity route for the power to be taken to Ground - so high that the current will exceed the limit of the fuse or Breaker in the panel that supplies the Hot lead, and it will blow out.
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That stops the current. The second is that, during the very short time all that takes, the exterior case you can touch will be VERY close to zero volts anyway, so you are unlikely to be shocked. Now, if you install a green grounding wire to a nearby water tap, it may or may not be able to carry all that current and provide the protection a real Ground system can - it depends on how good the substitute ground connection is.
But it should be able to handle the small currents from electrical noise and static charges IF it is actually connected to the earth. You can actually buy the simpler one-circuit version of these at any electrical supplies or hardware shop. They look a lot like a normal 3-prong double outlet but more expensive and you mount them into the wall box in place of the old outlet device.
Obviously, before starting you MUST isolate power from the box before opening, by removing the fuse or shutting off the breaker that supplies this outlet box. If you don't understand house wiring you are best advised to have this item installed by someone who does, like an electrician.
Blown Fuses and Tripped Circuit Breaker Causes
If you are competent at home electrical systems, see end of this paragraph. Once properly installed, what they do is to constantly measure and compare the currents flowing in both the Hot and Neutral parts of the circuit. If they don't the GFCI interprets that to mean some current is leaking out of the circuit to somewhere else, and that could be a big problem.
So it shuts off the power or "trips out", just like a circuit breaker does.
Once you fix the original problem, you use the Reset button. You can test at any time with the Test button, and it will trip out for you. The intriguing part is that this device does not need a true Ground point to operate, so it can work in an ungrounded outlet box. It just uses a different measurement to decide when to shut off power. So it provides very similar safety protection for people and for many appliance malfunctions, but it does nothing for getting rid of electrical noise and static charges. Now, for those competent to install a GFCI, here are notes to use; all others skip down.
These are the supply connections to the double outlet. It is a Hot connection on the Load side of the device just like the small right-hand slots that you can use to power additional outlet boxes further down the circuit layout. If there's a cable leaving this box to power other boxes, use this "Output" Red as the Hot supply going out on that cable.
I was going to rub the mud off with my left hand with the rag I had. Immediately I knew what that earlier sensation was on my wet hands and wet hose. I went to the back of the truck and unplugged the AC shore power to the truck and touched the truck again. No shock. The back of the truck was dry, and the cord was dry too. The puzzling thing was it was all hooked up to a power drop from the ceiling with a GFCI outlet.
He came out to the truck and told me to plug it in. Well, he touched the aluminum ladder assembly and he got a nasty shock from that.
Faulty Neutral Ground Wiring on a House
I unplugged it, he touched it again and nothing happened. The vehicle was then sent to our maintenance facility the next day we kept it unplugged after that. They plugged it in yes, a mechanic got shocked and inspected the truck to fund out that the battery charger unit sat in a pan that had raised sides. Water had gotten into the tray and filled it allowing it to come in contact with the VAC feed terminals from the receptacle in the truck.