Bill Kielb

I agree, if they talk about SCCR Short circuit current ratings then they have a better understanding how things are ultimately rated. If the manufactures design has been certified, then their engineering has established it. It’s a 48 amp load so a 50 amp cord seems perfectly logical and the default short circuit current rating of the cord / plug is likely very much higher than 50 or even 60 amps at 240 volts dead short. UL 508A table SB 4.1 for power outlets is partially what you are looking for, except the ratings are in ka or thousands of amps over a time period. It’s far more complicated to get everything approved and to work safely so the engineering and certifications are the best values. some fun reading page 14: https://www.overcurrentprotection.org/wp-content/uploads/2021/08/Review-of-SCCR-and-NEC-2020-Presentation.pdf Still sometimes folks just have their own idea. I have been waiting for two months for a part time electrical inspector of one of our local villages to allow tandem breakers in the panel I have shown above. I was trying to add 1 circuit actually.I finally said the delay is getting so costly I will just change all the panels to newer with more positions. Approve the drawings already! 20 new 100 amp panels, drywall retrofit, labor, lots of extra money paid ……. By the end user.

I think the simple answer is the breaker is sized per code which treats continuous loads differently than non continuous because of the potential for extra heating produced in the breaker. Most breakers under NEC are designed for max loading of 80% for the same reason. The cords are sized and derated appropriately for corded conductors that also produce more heat because they are molded into a cord. The next size up rule often influences the materials to build things and stay safely conservative. Electricians in the states should be used to using 80% breakers, yet often when it comes to kilns they want to put a 30 amp breaker on a 30 amp kiln. Go figure, you would think they would be looking not to exceed 80% of the value of the breaker they just purchased or 37.5 amps. (125% of 30 amps btw) Is it a weak point? I view it as a design criteria. In North America breakers are generally produced and sized at 80% for continuous loads but will trip at there published amperage. The sizing is very much about the heat produced and the life and safety of the breaker. 100% breakers can be purchased, they need to meet very stringent testing standards before they are designated 100%.and usually have to be enclosed in a minimum size enclosure for cooling. There are many skilled electricians who deal with this daily, still there are probably many more line electricians that likely don’t so for kilns it is often a challenge. So virtually any retail breaker one buys for the home is an 80% breaker meaning it was designed to be loaded at 80% capacity for a continuous load.

The rule actually is in place to protect the breaker from overheating. It’s actually pretty common for resistive loads that could draw maximum amperage for a certain period of time. 3 hours here - I think. Anyway, the practice is to oversize the breaker by a fixed amount to minimize the heating on it. The kiln still draws 48 amps so many electricians are just not familiar with a kiln load which is considered a continuous load and has a specific heating effect on circuit breakers. Most electricians are used to loading a breaker with no more than 80% of its rated load, which by the way 125% is the reciropcal of 0.80. The rules just make things a bit more goof proof …….. if you know them. A 50 amp plug on a 48 amp load is really not an issue. The confusing thing is it’s designed to protect a typical breaker in a typical enclosure from overheating and degrading over time for a very specific type of load. An electric kiln.

Yes, full electrification means removing all natural gas and still being able to heat, cool, cook, hot water, dry your clothes and not cost more than the combined prior gas and electric. So, the most common single family upgrade is 200 amps residential. We do add 15kw supplemental heat though (like a large kiln), just in case everything fails. That fits ok in 200 amps, not 100 amps though. Larger than that services are limited to commercial or farm use here. Single family generally tops out at 200 amps in the Midwest. I’ve done so many I can recite the kw loads in my sleep. Heat pump Water heater 4.5 kw element, 500 w heat pump , range, up to 10.6kw, heat pump 9.6 kw …….. yikes! I can say the new heat pumps are FAR more efficient than just 2-3 years ago. PS. Don’t forget the copper tracer to go along with the fiber so it can be found when it’s broken.

No worries, hope it works out for you. When your uncle looks at it, the top right relay can simply go away connecting the wire on 1 to 7 and 3 to 9. Just left it in untouched for simplicity. It could become a backup for relay on the left marked A should it ever wear out.

Adamah art studios puts on events. Been there - nice facility IMO https://www.adamahartstudio.org/

Thought I would add here re: tandem breakers. Just was out looking at some old 1970 panel installs and came across a panel that detailed in the diagram how many and where the tandem breakers could go. The answer for this panel - no more than 4 allowed and they need to be at the bottom of the panel. This is a 20 opening panel that can expand to 24 using tandem breakers. This is actually sort of common as manufactures try and place them in a spot with the most cooling (the bottom). In theory they could generate double the heat of a single breaker.

I hate to say this but my best idea would be shielded cable for the thermocouple lead. This is all very speculative as a relay is worn enough to create lots of arcing noise and the guess is the noise is getting into the thermocouple circuit. Almost all circuits have noise suppression built in on board to combat this. So if I had spare relays, I would swap them out just to see if I had a particularly noisy worn relay. (Even with a new controller) Even so, how to guard against our new relay contacts from wearing and causing issues in the future? Sort of a total random thing actually if true. The shielded cable is my lowest cost idea that all kilns could benefit from but are almost not necessary these days due to onboard filtering etc… This is really hard to figure out without some really good test equipment and as such is very speculative. If you have a spare relay, change it. Try and route your thermocouple leads as far away from high voltage wiring as possible to decouple potential noise sources. Good grounding always helpful, especially the circuit board ground, however that is developed. It might be one of the screws on the board that fastens the board to the metal case is corroded and is designed to be the ground but no longer is a good ground because of the corrosion.

Since they are sheathed, not really twistable but that definitely is a technique. Since a relay can wear to the point of generating obnoxious arc noise (No good way I can think of capturing without an oscilloscope or digitally some way) just pondering if there is an easy one stop sort of sure fire way to minimize for future likely occurrences.

Yes, the center tap of the 24 v side. Definitely NOT the 240 v side

I am a big fan of the V6cf so even if you have relay noise, newer controllers are built to suppress it. If you can find a good deal on a v6cf I really like the controller and it has performed for many many years.. to check you r service ground takes a bit of investigation on the actual wire run. It should terminate at a ground rod outside your service entrance and be tight and well connected. Good to always check, it is a safety component of your service. Typical method below, there are several common methods.

The cooler observation MIGHT be relay arcing and electrical noise generated by the relays. Watched your video makes this a real possibility. Need to ponder a bit to see if there is something relatively goof proof and easy to suggest. One thing for sure - Making sure the kiln ground is actually connected from the kiln to a good earth ground is something to check and grounding the center tap of that transformer can be be very helpful with noise generated. If you have a shielded thermocouple wire, make sure the shield is ONLY grounded at one end ( preferably the circuit board end) Sounds silly but both ends would be a no go for sure.

Neil’s got the right overall questions. The simple answer is the usual solution is to produce the design wattage of the kiln with YOUR voltage. My knowledge is limited but Australia and 230v nominal is what I remember. Queensland was being modernized to 240v. Anyway best to match the original design wattage (which is the amount of heat your kiln was designed to produce) at your voltage which might mean changing your resistance. If you put your wattage into an internet calculator and solve for resistance at your nominal voltage that’s probably the best way to get the kiln to perform as designed. So to answer your question, lower resistance means higher current and wattage and likely needs new mains electric to comply with code.

Yes it is! When I said: “If you search Glazy.org for Matte, you will find many recipes. The Katz — Burke has extensive color test and ought to be easily adjusted from its present matte to ……” …… Because I thought it had just that. If you scroll through the page there seems to be a nice variety of adjustments, tests, even a modification called buttercream! Thought it might be helpful. I have definitely made smooth buttery true mattes in more than one way though.

Interesting these recipes seem to be Si:Al in the 5:1 - 6:1 range - sort of a Stull observance for me. Some appear to have R2O:RO in the 0.1:0.9 range. Just asking - these have proven durable in your use?

The thing that might interest you would be for 3” brick at 2350 f losses through the kiln wall end up to be about 5.29 btu per sq inch or 1.55 watts per square inch and need 3.5 - 4 + watts per square inch to work effectively over a reasonable number of firings. So pretty easy to know How many watts it would take to supply for your kiln given heating is prox. 100% efficient. Translate that to gas by understanding your burner will probably operate in the 70-80% range and the whole kiln thermally will probably in the 50% range. At least you have a credible idea of what your burner size might need to be. Not sure all that helps but gives you credible idea of losses at 2350 f (cone 10)

Nice to see all working. Your kiln is set up as single zone in its wiring as well. Right now your top and bottom elements are on a relay and your center is on a second relay. To zone it, the element circuits will need to match the zoning.

Natural gas / propane - auto ignition temperature is 482c - 649 c (1200 f) To be very safe so folks don’t create their own bomb we usually require the temperature of early (body) reduction to begin no less than 1500 f to be extra safe. No point in finding the cool spot in the kiln to only to blow up the studio. The L&L docs are for interior square inches so surface area calc. The data show for 3” walls kilns are designed in the 3.3 - 4 or more watts per interior surface area. Good data actually to gauge kilns by along with recorded losses at various temps. If you need 30,000 btuh and that burners flame length at that output or above is 12”, then the flame will impinge on the wall significantly for any shape less than 12” so to me, figure out required btuh, add your margins of safety and check burner requirements such as pressure, orifice, and flame length. Almost ALL of your heating comes from radiation, so an effective flame is key. Convection - not very significant especially at high temps.

The elements wear together so generally if it needs elements, it needs them all. Firing at cooler temperatures definitely makes a difference but really at zero outdoor temperature that’s on the order of 3-4% change to a kiln firing over 2000f. Yes, very cold especially for humans who live in a very small temperature range but most often does not affect the kiln to a large degree. I don’t want to completely dismiss the outdoor temperature though. As elements wear by about 10% most kilns begin having trouble making top temperature. So on a very cold day and a worn kiln, that 1,2,3 % from the outdoor temperature could add up to be significant. More of a function of we wish kilns were designed with more like 120% of the energy needed than 110%.

A well stocked drill index can make your orifice estimation easier. Reduction at bisque temperatures a bit difficult if I understand that correctly. We limit early reduction to 1500 f I believe to be safe. L&L has nice resources here https://hotkiln.com/sites/default/files/pdf/BTUS-Davinci.pdf for electric kilns and btu loss per sq inch interior at various temperatures which can easily be translated to watts per Square (your area here) as a guide using 100% energy conversion. Maximizing burner projection with minimal impingement maximizing the radiant area probably most important. I think I would have a good idea of the energy required at 100% efficiency and see what the burner projection or flame length at approx 150% of anticipated energy needs ends up as a start.

If you search Glazy.org for Matte, you will find many recipes. The Katz — Burke has extensive color test and ought to be easily adjusted from its present matte to semi matte, etc… by testing and increasing the silica in small increments till your desired sheen is achieved.

Generally requires new elements (240v single phase) and follow the circuit diagram for the 240v single phase model. So the cost of elements, your time as labor and misc wiring as may be required. Not knowing what you are used to or what your. Skutt presently is. To add automation with some form of digital controller then likely 400.00 - 600.00 or more in controller parts, relays, wiring and your labor to fabricate things such as an enclosure and install it all. Last things I can think of is electrical run to the kiln, maybe an electrician and maybe add a vent if you are used to that on your Skutt. Is it worth it? I guess depends on the funds available and whether you can buy the kiln you want already made. With all the bells and whistles you can have a new old kiln for let’s say 1k-2k and sweat equity. Can you find something already made for that amount with absolutely new elements, relays, etc….. probably not.

I did not look it up, I think you have the only possible, speculating we need on the order of 20 ohms to get a four segment parallel arrangement to be prox .5 ohms.

For this controller, knowing it errors anytime the actual temperature lags 100 deg f behind setpoint. If you are writing single test segment to 1000 f for instance, I would not go faster than 500 f per hour. It has a speed up and slow down function, seems a bit to learn. I think I would stick with a high speed rate no greater than their 360f degree per hour cone fire for early and intermediate segments. At top temperature most kilns struggle to make 110f per hour as their elements age, so that probably would be my fastest final segment here.

Thanks, it was a very first old piece and the lettering, sorry to say is mine and definitely looks it.