GFCI keeps blowing

jkarp said:

Actually, that's not a very good test. It could be there's a crack in the element that's taking in water when heating. GFCI trips based on current, not voltage so testing resistance isn't a reliable method.

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Oh but it is. Ohms law relates voltage, current, and resistance and it applies here like everywhere else. Water causes an easily measured resistance. The resistance causes the ground current, and we are measuring that resistance.

I just want to apologize to everyone. I can honestly say "I was wrong". My jb weld failed and the water turned it into chalk.



I originally used about 2 tablespoons of acetone to thin it and jb weld says to use no more then 1 teaspoon. People on here said it would work but it would just take longer to cure. Maybe the acetone just wrecked the jb weld apart like acid or something

Thanks for the update. It's much appreciated.

You really demonstrated the critical need for everyone to seriously consider GFCI protection with electric brewing. Electricity in a wet environment? You betcha!

I'm just glad you're safe, Cybershadow. It is for this reason that I'm not a fan of heat sticks. I would never put electrical connections underwater, even though many hundreds of people do. I use the same setup that Kal uses, and it's never leaked. Never. Not even during testing; it worked the very first time.

Sure, it costs more money to mount an element inside of a kettle, but I believe that it's probably the safest way - and you can't put a price on that. As an added benefit, if I blow an element, I can replace it with a backup in minutes.

Anyway, thanks for posting the outcome; it took a lot of guts to make that post, and hopefully, it will help somebody else that's in the same boat.

Successful autopsy!

Quaffer said:

Oh but it is. Ohms law relates voltage, current, and resistance and it applies here like everywhere else. Water causes an easily measured resistance. The resistance causes the ground current, and we are measuring that resistance.

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I'm quite aware of Ohm's law.

How exactly did you propose to test resistance under operating conditions?

Cybershadow said:

I originally used about 2 tablespoons of acetone to thin it and jb weld says to use no more then 1 teaspoon. People on here said it would work but it would just take longer to cure. Maybe the acetone just wrecked the jb weld apart like acid or something

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Wow. I'm one of the ones who said it should be OK. I stand corrected as J-B Weld DEFINITELY should not have done that!

On the upside, you should be able to re-use the element...

Chefkeith said:

Sure, it costs more money to mount an element inside of a kettle, but I believe that it's probably the safest way - and you can't put a price on that. As an added benefit, if I blow an element, I can replace it with a backup in minutes.

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Yup. I said exactly the same on Basic Brewing. Heatsticks may be cheap, but if you're going to have a dedicated brew kettle, you're far better off doing a mounted element with a simple weldless fitting.

Like I said in this post. Let me be more specific. We run the suspect heat stick until the GFI trips. This means that we had at least 4mA of current between hot and ground, which in turn means that the leakage path has a resistance of at most 30 KOhm. We now unplug the heat stick and measure resistance between hot and ground (the ground can be on the pot as well). We should see some resistance, it may fluctuate a bit, but it is not going to be far from 30K. The leakage path was already created seconds ago and it will still be there, if the heat stick caused the ground fault.

The GFI has already indicated that there is a ground fault. This resistance measurement is one way to verify what the GFI already indicated, or show that something else is at fault.

Quaffer said:

The leakage path was already created seconds ago and it will still be there, if the heat stick caused the ground fault.

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Right here's your problem.

Elements cool enough to touch almost instantly when shut off. If the problem really were thermal related, the short may disappear before you can get your meter on it. Meanwhile, monitoring amperage to ground during operation would show you in real-time what the GFCI is seeing.

jkarp said:

Right here's your problem.

Elements cool enough to touch almost instantly when shut off. If the problem really were thermal related, the short may disappear before you can get your meter on it. Meanwhile, monitoring amperage to ground during operation would show you in real-time what the GFCI is seeing.

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I thought you said water leaking in was the problem? It would still be there.

Sawdustguy said:

I agree with you...check everything. I am not saying the J-B Weld would cause a direct short. I am suggesting it is a high resistance short maybe a couple thousand ohms lending to your leakage theory. Or then again I may be barking up the wrong tree entirely. It is just a theory. If I had a highpot machine I could try an experiment.

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Thanks for reminding me about a nightmare I had.
A few years ago I run into a similar problem with epoxy.
Snubbers and current sensors for motor drives were potted with black epoxy and ran at high temps.
Some devices shot the drives down after running from minutes to hours giving over-current indications.
Improper mixing and the high temp created enough leakages current to trip the sensing circuit.
Changing to clear epoxy (no carbon black) solved the problem.


Cheers,
ClaudiusB

Ranger9913 said:

you're exceeding the 80% rule using 14awg wire. 14 gauge wire is suited for a 15A breaker maximum and 12A at 80%. Using 12 gauge wire would put you where you need to be and would most likely solve your problem.

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Every time you plug any device into your outlets you make sure you don't exceed the 80% rule?

14 AWG copper wire is rated for 20A but the overcurrent protection devices shall not exceed 15A.


Cheers,
ClaudiusB