On my HLT I have 2 120 volt 1500 watt elements. I am going to power them using 1 230 volt circuit and connect them in series. The math works out for this and it looks like they will pull about 13 amps on each leg. Any reason this would not work?
Element wiring question
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SirJoshuaIV
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What type of wire is run, what gauge? Does it have a 2 hot legs, a neutral and a ground? If so, then I would imagine this would work. But wouldn't it be easier to just switch out the breaker to a 30amp single pole breaker? Each element draws 12.5 amps, so you would be fine on amperage and the existing wire should work (if the wire is rated to 30 amps) regardless of it is 3 wire or 4 wire.
I am no electrician, so take what I say with a grain of salt.
I am no electrician, so take what I say with a grain of salt.
No reason it wouldn't work. But, for the 230V circuit, total draw is ~13A, it's not really considered ~13A per leg, per se.
Yes, it will work but there is a very minor consideration here which suggests that the common point be connected to the 230V circuit neutral. The two elements won't have exactly the same resistance. Suppose R1>R2. If the interconnection between R1 and R2 floats (not connected to anything else) the voltage across R1 will be bigger than the voltage across R1 so that this element will get a bit hotter than the other and its resistance will go up even more causing it to get still hotter and so on. Conversely, if the common point is connected to the neutral the voltage across each element will be the same and the higher resistance one will be a little cooler than the other bringing the resistances closer to one another. This suggests that thermal runaway is possible in the series connection without neutral but it is extremely doubtful that this would happen with the elements immersed in liquid as even if one of the elements dissipates a few more watts than the other it's temperature is isn't going to be much different from the other.
Based on this if the neutral wire were available I'd connect them
H htr N htr H
rather than
H htr htr H
but I wouldn't stay awake nights worrying if they were connected in the latter configuration.
Based on this if the neutral wire were available I'd connect them
H htr N htr H
rather than
H htr htr H
but I wouldn't stay awake nights worrying if they were connected in the latter configuration.
I considered using a neutral but I only have a 3 wire 230 circuit so I would have to run a new 4 wire outlet with special plugs etc. I dont want to use the ground wire for a neutral for fear of being zapped.
Thanks
Thanks
Don't worry about it. The idea just popped into my fevered brain late at night. You should not use the ground wire for this purpose as you note.
I considered using a neutral but I only have a 3 wire 230 circuit so I would have to run a new 4 wire outlet with special plugs etc. I dont want to use the ground wire for a neutral for fear of being zapped.
Thanks
So it's a true 230V 2 wire w/ground circuit, not the rather common 3 wire 120/240V (or perhaps in your case 115/230V) dryer type circuit using neutral/ground in common?
All 3 wire 230 volt circuits are the same, however you look at it. I work in commercial refrigeration and there are some ice machines that require a dedicated neutral for the computer board. If you do not have a 4 wire 230 volt circuit you risk losing the board and voiding the warranty.
http://www.hoshizakiamerica.com/techtips/Pdf/All/tips153.pdf
http://www.hoshizakiamerica.com/techtips/Pdf/All/tips153.pdf
What I say next probably depends on if you are going to speak in common parlance of neutral and ground wires, or use the Code-correct grounded and grounding wire terms.
In common parlance, 120V comes from one hot leg and neutral, the circuit may or may not include a safety/equipment ground wire. Using the Code-correct terms 120V comes from one ungrounded wire (the "hot" wire) and one grounded wire (the "neutral"), and may or may not use a grounding wire (the safety/equipment ground).
So, at my house, in common parlance 120V comes from one hot and neutral. In code-speak my 120V comes from one ungrounded wire and one grounded wire - again, not to confuse grounded with grounding.
Clear as mud, eh?
In common parlance, 120V comes from one hot leg and neutral, the circuit may or may not include a safety/equipment ground wire. Using the Code-correct terms 120V comes from one ungrounded wire (the "hot" wire) and one grounded wire (the "neutral"), and may or may not use a grounding wire (the safety/equipment ground).
So, at my house, in common parlance 120V comes from one hot and neutral. In code-speak my 120V comes from one ungrounded wire and one grounded wire - again, not to confuse grounded with grounding.
Clear as mud, eh?
I do understand that the wires come from the same place. However a neutral wire will carry a current while a ground wire is just there to discharge unwanted surges and static voltage. That is why a 120 volt circuit has both a ground and a neutral. 99% of the time it probably doesnt make a bit of difference.
The ground wire is there to insure that cabinets, metallic conduits and the frame of any equipment connected to the circuit is at earth potential in other words to provide a sure path for hot-to-frame fault currents other than through someone who happens to touch the frame. This is not intended to be a current carrying conductor and this notion is reinforced by requiring certain circuits to be equipped with interrupters that open if ground wire current is sensed.
Yeah, I'm guessing you do understand that but there seemed to be some unclarity about neutral and grounding in the earlier posts.
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