Re: [LAU] ground loop hell

( ... ) Modern American electrical code requires a big-sized bare conductor (and some minimum length requirement that I forget) coiled into any poured concrete foundation. This is an effective ground. Simply drilling into concrete and installing some conductive rod is ineffective. Some practitioners use multiple ground rods, all connected together, driven into the earth, with a big conductor from the ground rod array to the service entrance. There are different sizes of grounding rod, from 1/2 inch to 1 inc diameter. Most of us have no control over the electrical wiring we use. With rare exceptions, initial electrical wiring is proper. Problems show up after non-electricians (handy personages, cheap M. Mouse laborers...) show up to extend or repair things. It's hard to wire things badly because the suppliers sell only devices that conform to the National Electrical Code--wiring things up is a matter of using the right tinker toy, hard to get wrong other than swapping the neutral and the hot (hot is either red or black and connects to a brass colored screw; neutral is white and connects to a silver colored screw; ground wires are either green or bare copper and connect to a green colored screw). If you own your own home and it uses a grounding rod, consider sinking another one or two or five or 27 and connecting them all together. Multiple grounding rods reduce the impedance of the barrier between a single grounding rod and the actual dirt into which it's sunk by a factor of the number of grounding rods (two rods halve the impedance between the service ground lug and true earth). Note that the size of the conductor should be huge (#4 at minimum, 0 or 00 or greater can't hurt and might be correct depending on expected ampacity). This conductor must connect each of the ground rods to the others as well as (a single length) to the service entrance bonding lug. Note also that the devices that clamp the wire to the grounding rods must be the correct size and material for both the rod and for the wire. If you have grounding problems, it's likely that the original grounding components have corroded or become loose. Either presents a potentially dangerous shock hazard. (Adding grounding rods to a working system does not as long as you do not break the existing connections.)