Chemgineer
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Melting metals
I've used a small electric melting furnace and noticed an electrical tingle in my hand when handling the graphite mold. I thought this was an effect
of a bad Chinese furnace.
However I have now used a separate high temperature hot plate (coiled element in a brick type setup) and I get the same tingle when trying to touch
melted aluminium with steel tongs.
Is this an electromagnetic effect from the 240v AC heating element inducing a current in the molten metals?
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Rainwater
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Not at 50/60 hz with a coiled element.
That sounds like a fault.
I would check the grounding of the furnace. Given that it is not blowing a fuse, it will be in the return path.
A gfci outlet should keep use safe if your not electrically proficient.
[Edited on 5-9-2024 by Rainwater]
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Twospoons
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It could also be a fault with your house wiring. I had a similar thing happen when the neutral connection to our house corroded through - anything
earthed and metal was tingly.
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Chemgineer
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The strange thing is I am only touching the molten metal with a steel tool, the crucible it is in is isolated from the heating element.
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unionised
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Many "insulators" become slightly conductive when hot.
So it's possible that you are feeling a leakage current.
Graphite is quite a good conductor.
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averageaussie
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forgive me but how are you feeling the electricity? outside of a small arc like in a static shock I'm not sure how you would feel an electric tingle.
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Chemgineer
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I'm feeling a frequency buzzing up my arm. I am wondering if the refractory brick that has the heating coil in it is actually slightly conductive.
Either that or the molten alluminium is have a current induced in it my magnetic induction.
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Morgan
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So when you turn off the voltage does it still produce the "buzzing" or resonance?
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Chemgineer
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If i turn the furnace on with solid alluminium in it and try, I don't get the effect, only happens when its up to temp and melted.
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Rainwater
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Quote: Originally posted by averageaussie  | | forgive me but how are you feeling the electricity? outside of a small arc like in a static shock I'm not sure how you would feel an electric tingle.
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Getting electrocuted is one of those things that can be neither be properly described nor ever forgotten. It's almost the same as being tasered but
mostly not as overwhelming due to mains frequency being 50/60 and a taser being a lot more
A simple test. Get a dmm or something that can read continuity or resistance and voltage.
Your country will determine which is what, but with the unit unpluged from the wall, test all 3 prongs to the frame of the furnace, only the ground
pin should have continuity to the frame.
If none of them have it, problem found.
Next, same thing but there is a relay in the way of testing. So plug it up, turn it on, and get to smelting. Once your melt looks nice, use your meter
again and check for voltage on the case
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