I have a Sundance optima spa, around 1998, indoor. It's wired with a 50A dedicated 230V circuit. The heater is a cylinder maybe 3" in diameter mounted directly on the control box.

After working fine for many years, the breaker started tripping sporadically, then with increasing frequency. Local spa guy came out, pointed out some leakage from each of the two pumps (one 2speed) and suggested replacing them. He wanted to replace the whole units - I decided to just replace the wet ends myself - MUCH cheaper.

Wet ends replaced, no more leaks, but breaker still blows. Seems like if the heater is on, it blows quickly, but if no heat, then it goes for a while (the latter no conclusively proven yet).

I saw some notes here about measuring resistance to ground, but each end of the heater shows infinity to ground. There was about 11 ohms between the two heater terminals. Now I was only able to get to the spa about 15 mins after it blew, so maybe the heater had drained by then?

I also disconnected the electrical supply line from the control unit (with the breaker off). Each leg of the supply line (at the spa) measures about 10-30K ohms to ground. With the supply disconnected, each terminal block on the spa - where the supply line normally connects - showed infinity to ground.

So the spa side looks good from that respect, but should the resistance to ground of the supply line be that low? I'd rather not disconnect things at the circuit breaker end, since then I have to cut power to the house (or work on an open panel).

I don't know that it is blowing due to a ground fault vs. overload, but nothing seems hot, so I suspect a ground fault. Is there a more definitive way to tell? I suppose I could do a current measurement and see what that shows.

I'm running a longer test with no heater on, to see what happens there.

Any suggestions very welcome.

...Mike

So, the pumps were leaking a little water, not electrical current, right?

Anyway, you're usually looking at one of several culprits with this trype of issue, though there are always exceptions.

First, disconnect BOTH heater leads, see if the problem disapears. If not, check for burnt/damaged wires at the main breaker, subpanel, and main terminal block. If they appear fine, see if you have an ozone generator installed. If so, disonnect power to the ozone generator.

yes, it was water leaking.

Turns out the problem was at the circuit breaker. Replaced it, and all things look good now. Thanks for the help.

mkraley, or anyone else.... Can you elaborate was your breaker in the panel bad. Did you just replace the breaker? I am having similar issues. Recently bought a new heater element. was running great for about 2 months. Now the heater runs for about 10-30 minutes and then cuts off. (Heater light was on entire time till the breaker trips.) If I reset the breaker it'll run for a another 10-30 minutes and trip out again. GFCI circuit near Spa does not trip, and tests out fine. (BTW: I have a Crown Spa with a pneumatic/analog spapack, 220V Heater and 2 speed pump setup with a 15 long stainless 3" Heater at the top backside of the control box. The thermostat is on the left side of the control box. I recently replaced one of the contacters for the heater and it was working great.) Photos here: http://spaforums.com/viewtopic.php?t=3987&highlight= If I turn the heater control way down in temp so the heater never cut's on (I live in Florida) the spa circulates at any speed indefinitely. I have not done any testing on the heater element with ohmmeter but I can if I know what to test for. So I either have some kind of heater problem... or possibly the breaker (or connection) in the panel is bad. I bought the breaker and external GFCI box when I got the spa running about 6 months ago. One more thing.. when the original heater went bad it used to trip the GFCI and the 200A house breaker and not the the 50A panel breaker (2 pole). Not sure if this is related, or is indeed a sign of a bad breaker.. I'm hoping that it might be the breaker since this is a cheap easy fix. breaker breaker... just had to say it a few more times... " title="Smile" />

There was a bad connection between the breaker and the panel. I think there was some oxidation between the pigtail and the panel screw. This caused high resistance => heat => an even worse connection. The wire was melted.

Thanks. Sorry I did not notice your post was a few years ago....

Is that one thing that can cause what they call a "dead fault"? I have heard that term while troubleshooting the other symptom of the 200A breaker tripping instead of the 50A breaker.

I will inspect/replace the breaker and connection and post results.

I noticed that when the heater and pump were running that the breaker was warm-hot on the outside of the panel in the house just before it tripped.

I shutoff power to the panel and replaced the breaker and reapplied the power and the problem is fixed. The new breaker does not even get warm after an extended time.

The old breaker which I bought new less than 6 months ago was a little loose when pushed in all the way on the the copper load bar. (my electrician installed it the first time so I did not notice it was loose) This was on one of the hot wire connections at the back of the 50 A breaker. The 6G wires leading off to the outside GFCI box showed no signs of heat, but the back of the breaker where it interfaced the copper load bar had some black dust indicating heat corresponding to the black 6G wire.

The heater uses both poles and more current so this could explain why it was only popping the breaker when the heater was running for a while.

Thanks for your help guys. Hope this helps someone else.
( Disclaimer: working with the Breaker Panel is dangerous, consult with an electrician as I did, if you are unsure)