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Helmsalee

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About Helmsalee

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    — Downeast Maine

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  1. Neil, thank you for the information. This is very helpful. Especially thanks for the explanation of the fused disconnect. Makes perfect sense. Helmsalee
  2. Thanks, Roberta12. I hadn't thought of the insurance angle, though of course I intend to advise our insurer once the building is complete and fitted out. I think that, on the front loader, the cover of the panel swings away, so shouldn't be a problem. I look forward to hearing what Neil has to say. Mark C., thanks for the advice to PM Neil. I've done that, and am eager to hear what advice he offers. Helmsalee
  3. Thanks for your input, Fred. Yes, I'm looking at the EFL2626. Sorry about the typo. I've edited the title of the post to correct it. The shipping weight of the EFL2626 is only 575 lbs (only! hah!). I figure on casters and with a little extra volunteer muscle, I could push the kiln around if it were on casters and I were motivated enough. But I see your point about fewer wire connection points. I've rewired a sailboat, and know well the virtues of continuous, and short, wire runs. I don't have much experience with AC, and frankly it scares me. So I want to do it right. About the fuse versus breaker, I've cut and pasted the entire text of the relevant pdf file I found on the L&L website. Here it is: ----------------------------------------------------------------------------------------- NOTES CONCERNING CIRCUIT PROTECTION FOR ELECTRIC KILNS Electric kilns are resistance heating devices. The electrical circuit that provides power to the kiln must be wired in accordance with the National Electrical Code (NFPA 70, last edition is 1996) as interpreted by the local authority having jurisdiction where the kiln is located, e.g., a township building inspector. The circuit can be defined as the device (kiln) itself plus the wires (conductors) supplying power to it. There are two common methods of protecting electrical circuits: fuses and circuit breakers. Fuses self-destruct when they sense an overload in the circuit. Circuit breakers are commonly used in new construction; they trip (turn off power) when they sense an overload, and can be reset (turned back on) when the circuit is returned to normal. Circuit breakers are more convenient because of this feature. However, they can cause nuisance tripping and ruin kiln firings when they trip part way through a firing. This is because most circuit breakers are activated thermally; if the circuit breaker temperature rises above a preset level, a bimetallic element inside the circuit breaker opens, and the power is turned off. This works well most of the time; however, over time the bimetallic element becomes weaker because resistance heating circuits are at their rated load longer than other types of electrical loads such as motors. Eventually the circuit breaker becomes too weak to hold itself closed over a long enough time to finish a kiln firing, unless the circuit is drastically oversized to compensate for this gradual aging process. There are many different types of fuses, including dual-element time delay, one-time, sub-cycle, etc. Most of these designations relate to how quickly a fuse will “blow” in response to an overload, and these types of fuses have been developed to protect not only the circuits, but also varying types of equipment. For instance, SCR’s (silicon controlled rectifiers) need to be protected from voltage spikes which can occur within 1/60 of a second and destroy the device - these are usually protected by ‘semiconductor’ fuses which are very fast acting, current limiting, and have no time delay. Another consideration in selecting fuses is the interrupting capacity in amperes - in other words, how big a short circuit can be opened by the fuse. In large industrial plants this can be an important factor, because if enough power is available it would be possible that a short circuit would allow too many amperes to flow into a circuit for a general purpose type fuse to interrupt - which could potentially cause an electrical fire. Most residences and small commercial shops do not have enough power available before the main circuit protector (usually a 200 amp circuit breaker) would open, and a small interrupting rating (10,000 Amps or 50,000 Amps) is enough. For protecting kiln circuits, ‘one-time’ general purpose type fuses should be used. These are inexpensive, have no appreciable time delay, and are available in a large variety of sizes. They are also widely and easily available, and are made by several large fuse manufacturers. Different manufacturers have different designations for their ‘one-time’ fuses; some of the more common ones are: MANUFACTURER MAX RATED VOLTS INTERRUPT RATING FUSE DESIGNATION LITTELFUSE 250 VOLTS 50,000 AMPS NLN BUSSMAN 250 VOLTS 50,000 AMPS NON GOULD SHAWMUT 250 VOLTS 50,000 AMPS OT LITTELFUSE 600 VOLTS 50,000 AMPS NLS BUSSMAN 600 VOLTS 50,000 AMPS NOS GOULD SHAWMUT 600 VOLTS 50,000 AMPS OTS ----------------------------------------------------------------------------------------- I look forward to Neil's input, and anyone else's who has more experience than I do (and that means nearly everyone in this forum). Helmsalee
  4. I'm making plans to build a pottery studio on my (very rural and remote) property, and am planning to buy an L&L front-loading kiln: L&L EFL2636. Three questions, before I place my order: Re: Vent. I've read on this forum that venting a kiln is not absolutely necessary if the kiln room won't have people in it while firing. But the (excellent, clear, and detailed) documentation on the L&L website says that all kilns should be vented because of the corrosive nature of the fumes inside the kiln, which shorten its life — quite a different concern than the concern for human health. My studio will have a separate kiln room, divided from the rest of the studio by a wall with a door that will be closed during firing. It will have a window that will be open in nice weather, and a gable fan that will always run during firing no matter the weather. The studio building itself is on a different part of the property from my house. What do you think? Should I buy the vent kit or not? Re: Wiring. The kiln I've chosen has two wiring options. One is to hard-wire the kiln to the fuse panel. The other is a 6-foot cord that plugs into a receptacle wired to the fuse panel. I thought I'd prefer the plug-in option so that I could buy the optional casters and move the kiln if necessary (though I don't imagine it would be moved often, or even ever). Do you see any downside to the plug-in cord option? Re: Fuse. The L&L documentation for this kiln says that a certain kind of fuse should be installed instead of a breaker because breakers are more apt to trip and ruin the firing due to the nature of the energy demands. Sounds reasonable to me, though I imagine my electrician will press to install the usual breakers and I'll have to insist. Any opinion about this? Thanks in advance for any advice. Helmsalee
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