Lee 4 pound pot electrical surprise

[oley55]

I primarily use a Lee 4/20 bottom pour pot, but also have a Lee 4 pound pot I use for this and that (salt bath annealing and small batch different alloy casting). A few weeks ago I was using it and thought I felt a tickle but didn't give it much thought. A few days ago I was using it right after I had been running a hot plate and the 4/20 and had my 20 amp GFI breaker pop a couple times. At first I thought perhaps the breaker was popping because of previous higher current usage, but made a mental note to check the pot.

Today I remembered and popped the cover off to make sure nothing was touching stuff it shouldn't and saw no problems. So I plugged it in and checked the pot carriage/body and found 124 volts. Myself told me, "hey that's not good!" I did some partial disassembly to mostly isolate the heating element from the carriage and pretty much confirmed the short was in the heating element. Fortunately as a "proper prior planning prevents piss poor performance" precaution I had ordered the free replacement parts from Lee (pot, thermostat and heating element) a couple years ago. After a lot of fiddling I finally pulled the original heating element out and installed the new one and viola just like magic, zero volts coming off the carriage or the heating element.

Close inspection of the old element failed to show any abnormalities. The insulation inside each end of the element appears intact, so somewhere inside the element coil something has failed. Frankly I have never given the possibility of a coil short a thought. My thoughts/experience have always been when an element fails it either just quits heating or burns through with a welder like arcing sound. I have never once considered a short like this.

Now I'm thinking I should maybe better replace my Lee two prong power cords with three prong grounded cords.

[imashooter2]

I found the melted salt gets inside the pot housing through the 3 screws on the rim. I wonder if that happened to you and the salt somehow corroded the element?

[jdfoxinc]

Use glass beads or fine silica sand as a heat transfer medium.

[oley55]

I found the melted salt gets inside the pot housing through the 3 screws on the rim. I wonder if that happened to you and the salt somehow corroded the element?

there really isn't any pitting or corrosion on the element, but surely a possibility.

why the element shorted is less of a concern than how it could operate in a shorted unsafe condition. Guess it's a good thing I never felt inclined to cast boolits barefoot or in soaking wet shoes. LOL

[imashooter2]

Indeed! [smilie=l:

[sniper]

Use glass beads or fine silica sand as a heat transfer medium.

That's what I love about the forum. Always something new to learn!
So, what's the procedure for using the beads or sand? How long does it take for the media to reach working temp., and what temprerature must be set on the Lee pot? How long to leave the brass for complete annealing?
Thanx! :)

[oley55]

That's what I love about the forum. Always something new to learn!
So, what's the procedure for using the beads or sand? How long does it take for the media to reach working temp., and what temprerature must be set on the Lee pot? How long to leave the brass for complete annealing?
Thanx! :)

yeah, some more info would be interesting. It seems like the heat transfer couldn't be as fast or as complete as the submersion in a liquid. The liquid is in total and complete contact with the surface of the brass. Beads or fine silica would still have contact voids, or so it seems...

But I worry these thoughts/questions will bring on the dreaded AMP and/or other annealing processes debate. Folks got some strong feelings about this for some reason. If my way works for me (right, wrong, or ineffective), why bust my chops about it?

[Stewbaby]

Use glass beads or fine silica sand as a heat transfer medium.

So you’re saying you fill the void around the heating element with that?

[imashooter2]

I’m pretty sure he means you fill the pot with the medium instead of salt and the process is similar to molten salt bath. Dip the cases into the sand.

[jsizemore]

Most of those elements are built with a resistor wire surrounded by ceramic material and then clad with a metal sheath. Sometimes that resistor wire gets a bit close to the metal sheath. If you had a ground on the pot, it would trip the breaker with the bad element. That would be the short you are referring to. You don't want to become the ground connection and become part of the shorted circuit.

If you read long enough about the AMP annealing system, some folks have taken a different piece of brass from the same lot and got a different annealing time. So, not so perfect. I know folks that use a torch and socket. Others melted lead in a pot or salt or beads in the the melting pot. My friends are all happy with their methods. I use a Bench Source. After I get it setup and running, I just got to be the monkey that keeps it full of unannealed brass.

[oley55]

I just got finished putting a 3 prong grounded plug on the little 4 pounder. The Lee 4/20 comes from the factory with a grounded plug. Go figure… ground on one but not the other.

[jsizemore]

My 4/20 was a 2 prong plug. When it cleared the box, I went to Lowes to buy an appliance extension cord. Already had romex connectors. Cut off the female plug and opened up the hole for the romex connector. Overkill? Heck yeah!

[Mal Paso]

I just got finished putting a 3 prong grounded plug on the little 4 pounder. The Lee 4/20 comes from the factory with a grounded plug. Go figure… ground on one but not the other.

The older 4-20s came with a 2 prong plug.

Thanks for the OP. The Lee elements I've seen are solid like oven elements. The short could be at the end where the wire exits. Something to watch for.

[oley55]

I looked very closely at the insulation when I had the problem, but saw nothing. No cracks, splits or buildup of possible conducting material.

It is of note the newest elements have insulation that protrudes out along the electric wire versus the 5 year old where the insulation is down inside. Regardless, hard to see how the electric could leak via either method. There is surface scale on the old element but nothing of note.

New element in PIC is for a 4/20, but the new one I installed in the 4 pounder was manufactured the same way. Disassembling for a PIC didn't seem necessary.

[popper]

New one has ceramic extending from the tube to increase path length for crud buildup. Ceramic cracks with expansion/contraction - crack fills with conductive crud.

[Mal Paso]

Thanks for the pictures. The amount of electricity necessary to trip a GFI or register on a meter is very small. A thin film of salt between the wire and jacket would be enough. A short inside the element is still possible but less likely. Whatever the cause a 3 wire plug and GFI is a great idea.

If you have an Ohm Meter you can measure the resistance and determine how much electricity would flow.

[oley55]

I suppose, but we should keep in mind the thermostat, wires and ends of the heating element are in the mostly sealed tower separated from the pot. The element coils around the pot could could see some salt intrusion. The inside of the tower shows zero signs of salt or corrosion.

I have contemplated wiring the coil direct into an outlet and then checking for a short or leak, but I already have too many electrician pliers n cutters with arc created wire stripper slots. I ain’t the most electrically savvy guy

[Mal Paso]

I suppose, but we should keep in mind the thermostat, wires and ends of the heating element are in the mostly sealed tower separated from the pot. The element coils around the pot could could see some salt intrusion. The inside of the tower shows zero signs of salt or corrosion.

I have contemplated wiring the coil direct into an outlet and then checking for a short or leak, but I already have too many electrician pliers n cutters with arc created wire stripper slots. I ain’t the most electrically savvy guy

Ya, that would push my thinking toward a short in the middle. Some things aren't worth investigating, it's enough to change the part. The 3 wire plug was an excellent idea especially since now we know they can short.