Mark Bannister wrote:

24 watts could easily be overwhelmed by a long hard freeze I would
think. At 110 volts 1240 watts is only a little over 11 amps
(1250watts/110 volts), not really all that much. You may have a weak
circuit breaker. A typical 110 volt line would be on a 20-30 amp

Even in the US, I don't believe you're permitted to use more than a 20 amp
breaker on a standard branch circuit. In Canada you may not use more than
15amps.

breaker (I guess this depends on where you live).

Yeah, but the pond's probably a long way from the nearest outlet on a
too-small extension cord. 1250/15 = 83V, which is one heck of a voltage
drop, but perhaps not impossible if the house is on the end of a long rural
run - where voltages tend to fluctuate quite a bit anyway.

So, rtk, the lessons learned a
(1) don't use extension cords (I bet the LG de-icer said that, too - because
I seem to remember somebody actually noting that, here)
(2) when you must use an extension cord, use one that's big enough: for this
job, that means _at least_ 14Gauge.
(3) when you start having electrical problems with your pond, get smart and
call an electrician - it's _so_ much better than burning down the house or
electrocuting your spouse (unless of course you want to electrocute your
spouse)
--
derek