Water main earth

[PBC_1966]

I have a vague memory of carrying out an experiment with a beaker of water some years ago, and as best as I can remember used a couple of electrodes suspended over the top, probably about 3 inches long and a similar distance apart. They were just stripped lengths of copper cable, probably 2.5 sq. mm or similar, not plates. I can't remember the exact current figures, but I recall that with 240V AC applied to the "pure" tap water the current was relatively low, maybe under 1A, but by the time I'd added enough salt to form a saturated solution it was well up into the range of several amps, getting near 10A (and, of course, the beaker of water was soon bubbling away nicely!).

The "pure" tap water was in East Anglia, so already quite hard water.

 

[Echo the husky]

That reminds me of the salt water dimmers used in old theatres!

 

[JohnD]

you must be very old!

I've seen wire-wound, and I've seen carbon block.

 

[Echo the husky]

im 27!

 

[JohnW2]

I have a vague memory of carrying out an experiment with a beaker of water some years ago, and as best as I can remember used a couple of electrodes suspended over the top, probably about 3 inches long and a similar distance apart. They were just stripped lengths of copper cable, probably 2.5 sq. mm or similar, not plates. I can't remember the exact current figures, but I recall that with 240V AC applied to the "pure" tap water the current was relatively low, maybe under 1A ... The "pure" tap water was in East Anglia, so already quite hard water.

In an attempt to get back into context .... I'm in a very hard water area. According to Anglian Water, during the period Jan-Sept 2015, the average conductivity was 655 μS/cm which, if I've got it right, translates to a resistivity of about 15.3 Ωm. If that's right, and I've got my further sums right, that means that a plastic pipe of internal diameter 12mm filled with such water would have resistance of about 134 kΩ per meter. In other words, if 1 metre of such water-filled pipe were connected via a zero impedance path to earth at one end and 230V were applied to the other end (of the water), one would expect a current of about 1.7 mA to flow - and for longer lengths of pipe, the current would decrease pro-rata.

... that's all assuming that no-one can find fault (far from unlikely) with my hastily undertaken calculations!

Kind Regards, John