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Kenny Pieper
01-16-2012, 03:01 PM
I am curious today what it would be like to get shocked with one of these furnaces. Has any one had this experience?

Pete VanderLaan
01-16-2012, 04:19 PM
If your transformer secondary is under 50 volts, it won't happen. The human body does not conduct under 50 Volts. I don't know your secondary.

Kenny Pieper
01-16-2012, 04:29 PM
Don't know what my secondary is. I have one of these staledman 300#ers. Why the cut switch on the door then.

Dane Gamble
01-16-2012, 04:52 PM
Pete - Are you referring to the power that the large cables handle that connect the control panel to the furnace? Hard to believe you wouldn't get shocked, assuming as you have said, that it was below 50 volts.

Dave Bross
01-16-2012, 04:58 PM
I've been shocked by a 12v car battery on some of those special extra swampy days here in the jungle. Nothing serious or even painful, but shocked none the less.

I suspect it's all about how well grounded you are.

Pete VanderLaan
01-16-2012, 06:15 PM
It does depend on how well grounded and how powerful ( pressure as in volts) the power is. You will certainly get burned but not necessarily shocked. I once inadvertnetly had an element touch my crucible and I gathered all day. The furnace did not have a kill switch. I was fine. Barefoot, standing in water maybe not so fine.

Dave's point about the car battery is the best demo of the phenomenon. Pick up a fully charged battery by the posts. Nothing happens. Put a wrench across the posts and watch the wrench disappear. Cats conduct well too, so do cows.

At one point a long time ago I was welding and just drawing rod to the point where i never looked up from under my hood. henry Summa was, unknown to me watering down the slab. I came to be in a puddle, welding. I am very lucky to be alive from what that did.

Steve Stadelman
01-16-2012, 06:47 PM
I put the kill switch into everything I built in case of something stupid and tragic like a short from the high side to the low side of lithe transformer. I honestly don't think that you will get a shock from a moly unit unless you are standing in a puddle. I was just looking out for everyone's safety by putting in a full safety system (with redundant functions ) because I never want to even give anyone a shock much less burn down their shop/home/studio or god forbid kill them.

Steve Stadelman
01-16-2012, 06:49 PM
They are expensive to build. I guess that counts as "moly shock".

Eben Horton
01-16-2012, 08:41 PM
i stuck a pair of jacks in an electroglass furnace with no kill switch and got the jolt of a lifetime... It was not pleasant.

Steve Stadelman
01-16-2012, 09:18 PM
i stuck a pair of jacks in an electroglass furnace with no kill switch and got the jolt of a lifetime... It was not pleasant.

Why? What?

Hugh Jenkins
01-17-2012, 01:58 AM
A wire melter would be an entirely different story.

Pete VanderLaan
01-17-2012, 06:19 AM
when people pat themselves on the back about not needing a transformer, which is in fact the case with SiC electric furnaces, you have to remember that "They don't need a transformer" and therefore the voltage is, um , 240V which is more than ample enough to pass through your heart and soul. Given that mullite conducts whereas high alumina doesn't, you should draw some conclusions here.

It's one of the big advantages of moly's that doesn't usually get mentioned.

Dave Bross
01-17-2012, 07:03 PM
I took a 240v hit from one of my wire melters when the kill switch malfunctioned.

I was standing on a rubberized carpet with rubber sole shoes... otherwise I don't think I would be posting this.

Hurt like hell even without being too well grounded.

I put in a warning light after that....light on... don't do it.

LOL at Pete's welding story. I've had excitement that way just from those drippingly humid days here and laying on the floor welding overhead. Watched one guy banging his head repeatedly on the bottom of a car with the involuntary spasms. We got him unplugged before he damaged himself too badly.

If you're gonna be dumb ya gotta be tough.

Eben Horton
01-17-2012, 09:11 PM
Why? What?

its a habit of mine... my furnace is gas fired.

I do it to heat up my jacks so i can wax them up before i start a piece. I just open the door a tiny bit and stick the blades in there for about 5 seconds. because i was holding the handle and stuck the blades in there, i completed the circuit. I wanted to lay down on the hotshop floor after that in case i passed out.

Steve Stadelman
01-17-2012, 09:23 PM
Well yes, cardiac arrythmias often cause that "I feel like I'm going to pass out" feeling. :(

Josh Bernbaum
01-18-2012, 07:00 AM
because i was holding the handle and stuck the blades in there, i completed the circuit.

I still can't fully understand. You must have touched one of the elements with the steel tool you were holding, right? Are the elements in that furnace design a jacks blades-length from the door opening?

Eben Horton
01-18-2012, 07:04 AM
My blades hit the side of the hearth ( door opening)

Pete VanderLaan
01-18-2012, 08:10 AM
Silicates and fireclays both will conduct at high temperatures. Aluminas don't. While I can't say for sure what Eben experienced, the kill switch on an SIC unit is an important tool. SiC runs at 240V which will happily conduct through you. Moly's to a great extent run on voltage below 50V but not all of them. The early 300# units used a 60V tap on a conventional 480V transformer that had 240V running into it. The transformer cannot differentiate between 480 and 240 so it simply split the load to being two 120V and one 60V tap. We wanted the 60V wired in series to 450/450 elements so that they ran at a proper 20V each. The later units used a 9/18 style element which needed 12 V to run efficiently. That in series took a 36 V secondary on the transformer, well below the 50V threshold to shock you.

What Hugh said about wire melters is absolutely true. They can kill you if there is a ground fault with no shutoff and they are more prone to it since a leak in a wire melter often causes a short which does not shut down the system.

The way this stuff is being built so casually these days actually reminds me of the fire service. Its codes are all based on tragedies that were bad enough to cause revisions to what we commonly call the "Life Safety Code". I am still expecting to hear of someone getting killed by a wire melter.

Pete VanderLaan
01-18-2012, 08:14 AM
My blades hit the side of the hearth ( door opening)
*********
Is it the case that the door was open so little as to not trigger the kill switch? As Dale would say "Bad Design". If the body of the furnace were live in general, it would be no different than touching your pipe down to the ledge while gathering. It would also suggest that the whole body of the furnace was live just sitting there. Scary.

Death is nature's way of telling you to slow down.

Scott Novota
01-18-2012, 08:36 AM
The Electroglass gloryhole does not have a kill switch and you will complete the circut if you are touching any metal that is grounded and touch the side of the beast with your pipe/piece. Think of having your arm touch the shield or the marver and the pipe/piece tagging the retention ring and you get the picture pretty clear.

I have have done the chicken dance of pain more than once. Public shop that I don't work in at all anymore but it is still being used as is despite my warnings.

Pete VanderLaan
01-18-2012, 08:42 AM
That's hard to beleive but well, there is a lawsuit waiting in the wings when someone dies. Emergency services are built on History

Thomas Chapman
01-18-2012, 09:59 AM
A number of years ago I thought to be clever and used a sheet of graphite for the floor of my (top loading) color pick-up box, to eliminate kiln wash on the colour rods. The elements sagged a bit and touched the graphite, and with no kill switch, I got the 220 jolt when I went in for a pick-up. My elbows hurt for a few days.

David Hopman
01-18-2012, 10:00 AM
The Electroglass gloryhole does not have a kill switch and you will complete the circut if you are touching any metal that is grounded and touch the side of the beast with your pipe/piece. Think of having your arm touch the shield or the marver and the pipe/piece tagging the retention ring and you get the picture pretty clear.

I have have done the chicken dance of pain more than once. Public shop that I don't work in at all anymore but it is still being used as is despite my warnings.

Mine has never done this.

Steve Stadelman
01-18-2012, 11:06 AM
Mine has never done this.



Yet.........

Lowell Duell
01-18-2012, 11:41 AM
At one point a long time ago I was welding and just drawing rod to the point where i never looked up from under my hood. henry Summa was, unknown to me watering down the slab. I came to be in a puddle, welding. I am very lucky to be alive from what that did.

are you saying that if you use a buzz box in a damp environment you risk getting shocked?

Dave Bross
01-18-2012, 01:45 PM
U betcha! just about guaranteed eventually.

Pete VanderLaan
01-18-2012, 02:42 PM
Yes, I am indeed saying that. Electricity seeeks the most attractive path to ground. Normally, the ground clamp on your welding rig is the most attractive which is why you can hold your work and weld. Don't stand in a puddle of water doing that or you may tweek the nose of Buddah. Damp locations are iffy. Sometimes you will just get a mild tingle. When It's talking to you, listen.

I have no idea how underwater welding works.

Virgil Jones
01-18-2012, 04:26 PM
In my last studio, before I enlarged the building and improved the drainage around the outside, the cement floor would soak up enough water that some parts of it were actually wet. I was kneeling on a dry (I thought ) area and welding equipment parts that were laying on the floor. I could feel the buzz thru my legs as I was welding! Not exactly an electric shock but definitely got my attention. I Put all my parts on plywood to weld after that. Also saved the floor from popping hot slag creating divots exploding out of the concrete floor.

Eben Horton
01-18-2012, 05:05 PM
*********
Is it the case that the door was open so little as to not trigger the kill switch? As Dale would say "Bad Design". If the body of the furnace were live in general, it would be no different than touching your pipe down to the ledge while gathering. It would also suggest that the whole body of the furnace was live just sitting there. Scary.

Death is nature's way of telling you to slow down.

the kill switch is bypassed. its always on, even when you gather.. zap!!!

Steve Stadelman
01-19-2012, 01:21 PM
This goes back to what I tried REALLY HARD to impress on everyone that would listen to me or who bought equipment from me. Electricity is dangerous. Not just uncomfortable. In the right circumstancees even a car battery will hurt or kill you. Welding is dangerous. Running an electric furnace or glory or annealer with no kill switch AT ANY VOLTAGE is basically criminal.

Eben Horton
01-19-2012, 05:54 PM
i agree.. i wasnt too happy with what happened. I think it might have dained my bramage.

Pete VanderLaan
01-20-2012, 06:38 AM
Whenever Steve starts using the Caps Lock key, watch it. I'm putting a kill switch on my toaster!