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Old 12-20-2020, 07:39 AM
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electric wiring question

So, I just had a wire burn up on the annealer that was built last year and as I look at the thing, I'm confused. The installation was of two elements. Both used 8 gauge wire to supply power and one element has two 230V leads going to the pigtails. The other, which is where it failed had only one wire taken from the power supply to the other element. That wire was attached with a split bolt and then a bridge wire was run from it to the other element end. This whole mess burned up but only after about one year.

What I don't get is why this worked at all. It clearly put a major load onto that wire and under normal circumstances, 8 gauge would be more than adequate. It had been covered with a shield so I didn't see it earlier. The bridge wire seems totally inadequate being made out of a piece of Kanthal about two inches long.
I'm going to replace both leads from the power source ( relay) with two 8 gauge wires, one going to each element end and then under a split bolt.

Thoughts?
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Old 12-20-2020, 10:30 AM
Eben Horton Eben Horton is offline
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Sods law. .
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Old 12-20-2020, 12:57 PM
Josh Bernbaum Josh Bernbaum is offline
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I don't know if I'm picturing what you mean by pigtails or not, but if it means wire nut connections like in home wiring, that might be tough to get everything tightened up properly with big 8 gauge copper. Do you have an option to mount two (if it's single phase) or three (if 3 phase) mild steel flat stock pieces to the back of the oven, insulated off the unit with some 1/2" marinite board? Then those flat steel pieces can be drilled and used like what I've heard called "bus bars". Each element-end gets wound and tightened down by washers, nuts and bolts to the bars, and at the end of the bars you can attach the power-feed wires using set-screw type terminals. Sorry I don't have all the terminology, I just play an electrician on TV.
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Old 12-20-2020, 01:24 PM
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The split bolt connectors are adequately sized. I don't know if they were loose yet. My question remains why it would be feasible to run only one side of the 240V leg to one end of the element where it gets connected, and then to bridge from that connection over to the other leg of the element.

It did fail but it took some time to happen. On the other hand I didn't use the lehr much at all in the last year.
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Old 12-21-2020, 12:19 PM
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Is that really it?
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Old 12-22-2020, 06:25 AM
Victor Chiarizia Victor Chiarizia is offline
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you running from a hockey puck or din a mite relay thingy. pic would be nice. i
m building a knife tempering oven now and am also starting to think about wiring. funny how you forget how you did something after a while. ah, oldish brain dysfunction.v
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Old 12-22-2020, 01:57 PM
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Let me try to rephrase it. Each leg of a 240V line is 120V. So if you only take one leg of it, you have a 120V hot lead. If you take that 120V hot lead, attach it to the end of a wire wound element rated for 240 and then take a jumper from that lead and attach it to the other end of the wound element, I cannot see in any way that this creates a 240V circuit. What surprises me even more is that it worked at all and then fried the jumper after a year. I had put the controller on 53% power to avoid our electric company's usurious $9.49 cent surcharge yet I can't see that causing the burnout either.

Why did this thing work at all?
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Old 12-22-2020, 02:05 PM
Steven O'Day Steven O'Day is offline
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Re-reading this. One element has 240v to pigtails, one hase 240v to one pigtail and the other pigtail is connected to the other element? It seems like this would work except for the heat factor of the wire connector but why would you do this?

Last edited by Steven O'Day; 12-22-2020 at 02:13 PM. Reason: re-read post
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Old 12-22-2020, 02:27 PM
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I haven't excavated what the builder did. This was all covered up. The problem I have with your suggestion is the upper element works great and the bottom one is dead. Each single lead has to be 120V. 2 leads makes 240V . I'll try to dig the wire out in the morning. Even so, that leaves me with three wires coming out of the MDR and it makes no sense. It is single phase.
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Old 12-22-2020, 08:01 PM
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one of the wires could be neutral
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Old 12-24-2020, 04:19 PM
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At this point I understand it better than I did. The wire coming from the MDR to the first pigtail is 8ga and goes under a split bolt. Then the jumper goes to the pigtail just below it BUT it's not the same element, it's the other element. I have to tear the cover off of the other two connectors to see what's up there but this appears to be wiring in series which doesn't make sense again because after the wire melt down, the jumper burned up yet the upper element still worked. That I don't get.

What is clear to me is that the use of split bolts like this probably was not the best connection in the world and the line coming to the first connection is overamped by also serving the second element. Each wire should serve one pigtail, not two. It melted well back into the conduit.
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Old 12-25-2020, 08:54 PM
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Franklin Sankar Franklin Sankar is offline
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Were there any dogs involved..😁
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Old 12-26-2020, 08:27 AM
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well, yes, my dog has been comforting me.

I think the jumper is a choke on the system when what is needed is an open interstate highway. I'm running two wires to it. The hotter it gets, the more resistance in the line so, the hotter it gets.
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Old 12-31-2020, 08:16 PM
Michael Ahlefeldt-Laurvig Michael Ahlefeldt-Laurvig is offline
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I cant follow your vocabulary, with pigtails etc , but the first basic fault is using coiled Kanthal wires in your annealer. Its a 50 year old throwback from the ceramists thats never left the US glass scene.
You dont need Kanthal, you’re not going that hot, you dont want exposed “hot” wires in an annealer.
You dont want the crap with making routed channels in soft bricks. You dont want bricks, you want insulation.
You want rod elements, as the grill in your oven.
Screw terminals and has been mentioned busbars- in my case .8 mm 1/2” angled stainless busbars. Solid, worked for 30 years. Only one broke due to a loose connection in that time
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Old 12-31-2020, 08:47 PM
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Circuit drawing

Is this what you are saying Pete?
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Old 01-01-2021, 09:54 AM
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I may try the oven elements. Henry Summa did it one time I was aware of using two, opposing each other on the walls, but he abandoned the notion and I don't know why.

What I do know is that this is unworkable from the point of view paying for the power. I ran the lehr five times in December and got my electric bill yesterday. It charged me five times for using over 5000 watts in a 1/2 hour period. The charge? 9.49 dollars each time multiplied by the current rate additional. That totaled 80 dollars alone. It was for delivery of the power, not the power itself.

I'm going to look at preheating it with propane. I can also turn on a lehr in the middle oof the night using a charge of .02 per watt, but then I'd need to run a second lehr. I can turn the percent down on the controller but it still penalizes me and takes too long to get ready. The power company no longer cares about power generation. It's in the usurious delivery system.
I also have the 30KVA generator that runs on propane but it's likely too loud for my neighbors.
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Old 01-01-2021, 10:53 AM
Tom Fuhrman Tom Fuhrman is offline
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I used stove/oven elements for years and had no problems. They are inexpensive and many times can be salvaged from people that are getting rid of an old range. I always thought they were a lot safer when students were around, as there was a certain element of safety not provided by the exposed coils. If you want to go over 1200 though, I would not suggest their use.
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Old 01-01-2021, 12:23 PM
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the 1200 is an excellent point.
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Old 01-01-2021, 01:11 PM
Michael Ahlefeldt-Laurvig Michael Ahlefeldt-Laurvig is offline
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Im not real current on information bu a few years ago there were special elements that would work continuously at somewhere above 800C
My annealer has always been just that, so the 1200f rating is fine with me
(Well, I have cooked a 14 lbs wild Atlantic Salmon whole in it once)
Although I can sympathize with salvaging things for repurpose - if you buy them from a manufacturer they are still affordable and you can choose length, effect, single or 3 phase, how much dead length close to the terminals, choice of terminals etc. You can also bend, shape them any way you like to fit your space. You can do a 180 degree bend with about a 1” radius .This can only be done before they are fired the first time. So you buy straight elements and bend them yourself
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Old 01-01-2021, 01:28 PM
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I ordered a 3500 watt one for 34 dollars. Thanks. I hope that does the job as far as watts go.

A pigtail is simply the kanthal wire wrapped around itself one where it would get connected to the load. It helps dissipate heat at the point where the connection frequently has the capacity to arc.
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Old 01-01-2021, 01:39 PM
Michael Ahlefeldt-Laurvig Michael Ahlefeldt-Laurvig is offline
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That rating your power company does on you seems like a real PIA
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Old 01-01-2021, 02:01 PM
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It would be $516.90 per month just for the lehr.

It's not sustainable. I am going to call my State representative about it. Its done by the utilities commission which i suspect of good old boy connections.
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Old 01-01-2021, 06:50 PM
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Where did you get the element.
Franklin
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Old 01-01-2021, 07:05 PM
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Amazon, American made.

let me try it first buddy. I got no cocoa balls... It's like Apollo 13. We're reading the Ammeter here. The trouble is , the bastards are American corporatists. They have zip for allegiance.
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Old 01-02-2021, 07:29 AM
Sean Jones Sean Jones is offline
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Ive found oven elements work well.
I bought the ones with the lowest surface load, the longest for the given power.
In my case three 1kW 240V elements in parallel supplied by a small SCR.
3 of fibre, internally the box is 18 x 18 x 24
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