Brian,
I used to do electrical work for a farm in my town. We would use heater tape around the water pumps in order to get water to the live stock.
I used to wrestle with various techniques for keeping water lines open, but thank god I bought an exacavator and we have buried lines to half dozen hydrants around the farm. Every once in a rare while you can freeze one of those. I'm not even 100% sure I know how but I assume in the cases I've seen they might have had slight leak at the seat that exceeded the drainage capacity of the surrounding soil so you got a water level established up the hydrant, but maybe I'm overthinking this and it was just CTWT.
Brian,
I am going to assume that an airstone is like a water bubbler. Maybe they make electric blankets to wrap around the trough to prevent the frozen water.
Right, an airstone is an aquarium and backyard pond aesthetic outlet for pumped air to do the bubbling. With fish, it oxygenates the water as well as keeping it from freezing if it is an outdoor fish pond. I don't know why there isn't more focus on this kind of device for water troughs. It may put the animals off, but I have found that the introduction of stray voltage (see below for more on that) from the standard trough heater approach is highly offputting to livestock - for obvious reasons, i.e. they tend to be well grounded unless you get them rubber horseshoes (mostly kidding although they make rubber boots that are substitute for standard metal horseshoes for riding. Of course, if the horses wore them in the fields this would pretty much frustrate the effectiveness of elecric fences, or you would have to run one or two ground strands as well as hot strands).
So back on the GFCI issue. I rechecked everything. The GFCI stayed on running the heater as long as I didn't use the suspect extension cord. I took the cord inside and warmed it up for 24 hours laying on the warm floor and hoped I might drive out any moisture that might be cause the tripping. My ohmmeter shows infinite resistance between all legs of the cord. But took it back out, plugged it in and it still trips as soon as I plug anything into it, despite the fact that these same appliances will run in the same GFCI without the cord. It is no great loss to need another 6' cord but I'm mystified as to how to really diagnose what the problem with the cord is if anyone has any ideas. The male end is a molded original. I shortened the cord and put a field installed female on it. Same cord was running these heaters last year without any tripping.
Brian,
As for stray voltage, that would be a real hot topic around here. I have seen lots of problems with stray voltage around pools. Sometimes it was caused by pin hole leaks in the Power Co. (POCO) primary underground feeders.
We would get readings between 5-30 volts around a pool. Enough voltage so that you feel a tingle when you touch metal, the pool deck and had bare feet.
No underground feeders around here lighting up manhole covers and frying dogs, or the like. We're in the sticks. It's all overhead. But I did some fairly extensive research on this last year. The Stray voltage to which I refer is the relatively ubiquitous Neutral to Earth Voltage, i.e., the line loss or voltage drop between of the return to the substation - which is exacerbated in rural climes because of the distance to the substation and a grid that was sized based on electric demands before exurban buildout.
Because the voltage drop is based on current, it varies around here from about 3 volts at low usage times to as high as 7 or 8 volts when a lot of power is being drawn first thing in the morning and early evening.
This potential is introduced to the exterior of any grounded appliance because of the bonding of neutral to ground at the box. And more ground rods or pounding them deeper, etc. is marginally helpful. The one thing I learned about this, that is the most helpful analytical tool, is current takes all paths to ground relative to resistance, as opposed to my earlier misconception that it takes the easiest path.
If I had any doubt what horses were experiencing, I've had some good bouts myself running electric drills and angle grinders with diamond blades in concrete where we are using water as a lubricant and to control dust. We obviously run the tools on GFCIs but once everything is thoroughly misty, I can get some goddamn good, i.e. painful, tingles off the casing of the tools when I am grounded but this doesn't throw the GFCI.
This is because the same amount of current is going out the line and back the neutral as far as the GFCI measures. The current that is zapping me is the small but potent potential (guess that is redundant but for emphasis) between the neutral and the ground which is not measured by the GFCI.
This is a subject I really like to talk about but it is only tangentially related to GFCI. If there is a stray voltage thread here I'll try to stray onto it.
Brian
