My kiln is running and going down in temp instead of up! What to do now?

[neilestrick]

Did the breaker flip instantly when the kiln started, or did it take a few seconds or minutes? If it flipped instantly, that's usually a case of a wire making contact where it shouldn't or something not being wired correctly. If it took a few seconds or minutes, that's usually a case of the draw of the kiln exceeding the rating of the breaker, or a bad breaker.

[Bill Kielb]

1 hour ago, feistyfieryceramics said:

Should I ask the electrician to measure the voltage if

Yes, he should but .........your kiln was designed to be 5000watts @ 220v so the gross resistance should have been 220^2/5000 (220volts square divided by 5000 watts)  or 9.68 ohms total and since three elements are in parallel, 9.68 X3 = 29.04 ohms each give or take some winding tolerance. This means your kiln will draw 22.72 amps which is less than the 25 amps rated on your breaker. When you run this same machine on 240 volts  using the right size elements you get 24.79 amps which is near tripping your 25 amp breaker as well so voltage matters a lot especially when calculating  which elements to wind.

Your current element set was also made in error as a 5000w 220v element set should be 29.04 ohms each and he made yours at 27.5 ohms (average) which is 5280 watts not 5000w. So technically he gave you a set that is incorrect based on his own labeling.

Anyway, what you have is likely near 6000 watts (especially if running 240v) 

I think you could complain and say they were wound beyond 5000 watts. He should have asked what the label on the kiln said and followed that. At best he miss-wound your elements on his bad math I guess.

I think I would have an electrician review it and see if he can safely following local codes increase the breaker size and will the present wiring etc.... need to be changed to match the new breaker size. If yes, then likely these new elements will  work  for some time but will also burnout quicker than they normally would.

My thinking is the electrician rout is easiest to get to a compromise finish, knowing that this kiln will end up as an overrated kin in the end.

[Bill Kielb]

12 hours ago, feistyfieryceramics said:

(test) button says 25 A above

Just read a bit more of this, This 25 amp breaker is an RCCB also know as a ground fault in north America. These breakers detect any small leakage of current to earth ground as well as overload. You appear to have three phase service available as well so very interesting. The 25 amp stands for just that, it will trip when 25 amp circuit is exceeded which certainly could be your kiln based on 5000 watts. This device has a number .03 which basically means it will trip very fast on .03 amps of current leakage to earth ground in addition to 25 amps load. Since this is the breaker that tripped, it would be good to double check your wiring and also for a qualified electrician to determine if a ground fault exists.

It is very possible that your kiln is three phase which means smaller three phase breaker such as the one on the right in your panel.  So tripping of the main breaker, (the one on the left with the test switch)  device could indicate a pinched wire for sure and not be an overload condition due to the slightly higher wattage of your kiln elements.

@feistyfieryceramics

Just keep looking at these pictures and .....
we really need to know which breaker, other than this main breaker controls the kiln to understand what and how it’s wired. I think it’s 11,12,13 ( my Swedish is non existent) if yes, what is the rating of that breaker? If you shut off 10,11,12 you should be able to confirm that it is for the kiln and the kiln will not fire.

I think the breaker marked three phase (trefas Utag)  is for your kiln. Your kiln wired at three phase will draw much less amperage than single phase so if this breaker shuts off the kiln, it did not trip from overload, instead a ground fault was detected by your main so pinched wire, a connection that is not ideal or touching ground (steel case) will cause the ground fault to trip. Post pictures of your element install, especially the connections if you can.

The higher wattage elements you can deal with later, if we solve this, you likely can use your kiln until replacement time and get the right elements next time providing everything is sized safely which is starting to look like it is actually.

sorry trying to write all this flipping back and forth between the pictures, I think you are going to find a pinched wire or somewhere where bare wire is touching steel, etc...

Btw, download these and keep them with your kiln, it appears to require a three phase breaker at 10 amps

https://www.cromartiehobbycraft.co.uk/files/Kiln Downloads/CTL Range Leaflet (1st).pdf

https://www.cromartiehobbycraft.co.uk/files/Kiln Downloads/CTL Range Leaflet (2nd).pdf

 

[feistyfieryceramics]

@Bill Kielb @neilestrick OMG! We did it! We figured out the problem with your help and now it is working now. I started the kiln at that same ramp of 500 C per hour for the paper test and all the elements burned the paper and the breaker didn't flip.

I'll tell  walk you though what happened and then maybe we can "regroup" to go over what I need to ask an electrician and whether I need different elements.

So last night; the first time we turned on the kiln, before installing the elements, I remember seeing that the orange light on the outside of the kiln was on when I passed by it on the way to the little/old kiln computer. I was able to program the computer before the breaker switched. I think maybe the "klink" of the elements turning on was when the breaker flipped.

One of ceramic insulators around the bolts that you attach the heating elements to in the electrical box  was already missing a little piece when we bought the kiln, but the chip location didn't allow the metal contact the frame. We thought maybe it had been further damaged during our installation of the new heating element and that maybe the bolt (and therefor the element was making contact) with the frame there. When we got to the studio this morning it didn't look like there was any further damage to that piece. BUT!!!!! We saw that the bottom bolt was definitely in contact with the frame and we checked and found that there was continuity between the element in the frame... we guessed that shouldn't be the case! So we adjusted all the bolts and all the insulators to ensure that this sort of contact would not be possible (and we will get a new insulator to replace the damaged one). After we adjusted everything there was no longer continuity between the element and the frame! And when we then measured each element again they were all 27.3 ohm.

See photo with magnified view in blue square. This turned out not to be the problem. When we looked at this photo last night from home, we thought it looked like the bolt was making contact due to the chip, but it turns the rolled metal edge of that vertical piece of metal just made it look like it in the photo.

The photo with the pink arrow shows where the element/bolt was contacting the frame!

 

 

 

 

 

 

 

[feistyfieryceramics]

@Bill Kielb @neilestrick

There is som old looking stuff in here so I am not sure if it is all in use but the really ancient looking thing that has a big "4x6" written on it is the fuse box. I've blown a fuse by using 3 hair dryers at the same time and have changed it. The plaque on there says V 500 A 25.

This other ancient looking thing that also has the sort of "counter" showing how much electricity we are using has a plaque that says 3 x 25A 380 V.

Here is the showing how much electricity we are using. Not sure what it's called. 

Here is the breaker list 11, 12, 13 were added when the 3-phase plug for the kiln was installed.

Here is the breaker. I've hav flipped one of these once when I had two hair dryers going (why did this flip the breaker but 3 blew the fuse?).

Then this is the 3-phase plug that the electrician installed for us. It says something about 200/346V and 240/415V.

[feistyfieryceramics]

So! I also just got a response from the electrician who we texted in a panic last night  He says can come by on Tuesday at 11. I told him that the kiln was working now but that I hope to have a list of questions to help us understand the electricity situation in the studio so we can do things safely, get the right elements, etc.

So my the next thing I am going to do after class today is run an empty bisque firing as I heard that helps extent the life of the elements. My husband who is a programer set up a webcam to take a photo of our little/old kiln computer so I can see it it is able to achieve the correct rate of rise and temp, etc. 

With the firing schedules you sent, there are unfortunately more segments than my computer allows. I can only set two rates of rise before a soak. How can I adapt these schedules for my kiln?  

[Bill Kielb]

27 minutes ago, feistyfieryceramics said:

With the firing schedules you sent, there are unfortunately more segments than my computer allows. I can only set two rates of rise before a soak. How can I adapt these schedules for my kiln?  

Nice work! I was afraid I was too late having reviewed the pictures and thinking more about it. Anyway when the electrician does come, at some point have him measure the voltage for you. My suspicion is it was 220 v at one time but probably  has been raised overtime by the utility (As most of the world) to 230v or even 240v. Anyway good to know for next element change. Your kiln has either slightly more power than new  because he gave you elements at about 5200 watts, or considerably more than new  by whatever percentage it is above 220v. All good though, now I know your kiln breaker is 10 amps per leg / 3 phase.

The most important part of the glaze firing schedule is the last 100c for proper cone bend so if you do need to dry everything out, then set a reasonable speed through thee firing, maybe 250c per hour. If you need to dry things out without a controller that preheats some folks  turn the kiln on, heat to just short of 100c and let sit overnight or run a drying program 25 c per hour to 100.

For bisque time is very important and of course the last 100c to get your cone to fall. Maybe stretch this last 100c by reducing the rate to 40c per hour or  so it has a decent amount of time at top temp with a  200 c per hour for the starting segment. Again to dry things you can always use the preheat to 100c and let sit overnight to dry thoroughly or create a drying program as above.

Great pics, you guys are getting picture  savvy, electric savvy,  and pottery savvy. Nice work!

[feistyfieryceramics]

3 hours ago, Bill Kielb said:

For bisque time is very important and of course the last 100c to get your cone to fall. Maybe stretch this last 100c by reducing the rate to 40c per hour or  so it has a decent amount of time at top temp with a  200 c per hour for the starting segment. Again to dry things you can always use the preheat to 100c and let sit overnight to dry thoroughly or create a drying program as above.

So for a bisque firing assuming I have already dried the pieces out... something like this? 200 C per hour to 963 C. Then 40 C per hour to 1063 C. Without a hold?

3 hours ago, Bill Kielb said:

The most important part of the glaze firing schedule is the last 100c for proper cone bend so if you do need to dry everything out, then set a reasonable speed through thee firing, maybe 250c per hour. If you need to dry things out without a controller that preheats some folks  turn the kiln on, heat to just short of 100c and let sit overnight or run a drying program 25 c per hour to 100.

Do you mean set it to 100 C and then turn off the kiln, or do you mean hold at 100 C over night? Alternately, I could set it to 25 per hour to 100 C while I'm in the studio and then set a new program for the glaze firing before I leave. Is it important to dry pieces out in the kiln after glazing? I was waiting 24 hours but then I read a post on the forum that certain glazes crawl if you don’t let it dry but that if your glazes do that, you can load and fire right away after glazing. What are your thoughts on that?

Assuming I have already dried the pieces out... 250 C per hour to 1122 C. Then 40 C per hour to 1222 C. Without a hold?  How about a slow cool for matt glazes or for healing bubbles?

3 hours ago, Bill Kielb said:

Nice work! I was afraid I was too late having reviewed the pictures and thinking more about it. Anyway when the electrician does come, at some point have him measure the voltage for you. My suspicion is it was 220 v at one time but probably  has been raised overtime by the utility (As most of the world) to 230v or even 240v. Anyway good to know for next element change. Your kiln has either slightly more power than new  because he gave you elements at about 5200 watts, or considerably more than new  by whatever percentage it is above 220v. All good though, now I know your kiln breaker is 10 amps per leg / 3 phase.

Okay so. All I need is to have him check the voltage? Great! If it is in fact 220 V in the studio, that's good? Then I have the right elements? If it is 230 or 240, the elements will still work but they will burn out faster because the kiln will be running at higher than 5 kw? How often should I check the resistance to see if they've changed by 10% or more (After that issue with the warping and the kiln turning off due to the pacman hinge, open the kiln up and stick a popsicle stick in there to make sure it hasn't rotated again! I like to be cautious because I feel sooooo bad if student work gets messed up)? Or is it better to record how long the firings are taking and then change the elements when I notice they are getting longer.

And since the breaker is 10 amps per leg and 3 phase that means it would be hard to flip the breaker from normal use of the kiln? I am definitely scared of the breaker going in the midst of a glaze firing if I am not in the studio.

Another thing that I am curious about is...with my original set of elements, the top burned out, the bottom looked in bad shape and had that "tooth" stuck to it, and the middle one looked pretty good BUT had the highest resistance of them all. At first we thought, maybe we should keep this middle element as emergency backup and reinstall it if another element goes out mysteriously, but with the higher resistance we are questioning that. Also I think we should just order a backup set when we know what the voltage is in the studio.

3 hours ago, Bill Kielb said:

Great pics, you guys are getting picture  savvy, electric savvy,  and pottery savvy. Nice work!

Thanks! It is stressful and scary but you feel a lot of pride after. Hopefully things go smoothly for awhile and my heart can stop beating so fast before the next issue comes up

 

Thanks for your help!

[Bill Kielb]

1 hour ago, feistyfieryceramics said:

So for a bisque firing assuming I have already dried the pieces out... something like this? 200 C per hour to 963 C. Then 40 C per hour to 1063 C. Without a hold?

To be conservative, I averaged the chart out and came up with 95c per hour to 950 and 25c per hour to 1063. To make things easy. No hold it’s about 14 hours. Plenty O time, if your clay is fairly clean and doesn’t need such a long bisque, you could speed things up after testing a faster schedule.

 

1 hour ago, feistyfieryceramics said:

Or is it better to record how long the firings are taking and then change the elements when I notice they are getting longer.

I like recording the time, you will notice in your glaze firings when it creeps up by one hour, then two, etc....  still you can measure anytime and the 10% rule is pretty decent.

 

1 hour ago, feistyfieryceramics said:

Okay so. All I need is to have him check the voltage? Great! If it is in fact 220 V in the studio, that's good? Then I have the right elements? If it is 230 or 240, the elements will still work but they will burn out faster because the kiln will be running at higher than 5 kw?

You almost don’t need him since you found the ground fault at this point. A once over would be nice. If he is there, voltage kiln off and on and amperage kiln on and maybe check all connections. You will use these numbers later to decide on things in the future. Speaking of which, if your element life ends up good (100 firings) at the higher wattage then you may choose to keep it that way. Most kilns are a bit underpowered which is why they can only tolerate a 10% reduction in power.

If these elements don’t burn open prematurely then I would continue to use them at the 27.3 ohm  design for 220v. It’s likely  going to be 4-8% more capacity (depending on voltage) as I recall which means you will likely wait much longer between  changes. If they burn open at less than 100 firings, I would drop back to the 5000w at your measured voltage design. My speculation, they will last just fine as long as they are kept free of debris.

....... and the 10 amp breaker should turn out perfect as this kiln will operate somewhere between approx 7-8.5 amps per leg, which is fine but may be a reason to order elements at the higher voltage next time. You would like to be 8 amps or less on the breaker as good practice in most codes. Probably a good question for your electrician while he is there.

I would not save any old elements except to cut up and use as inserts for hanging loops. I had a gal that would always take scraps and  embed them for her midfire  wall tiles for hanging.

[feistyfieryceramics]

1 hour ago, Bill Kielb said:

To be conservative, I averaged the chart out and came up with 95c per hour to 950 and 25c per hour to 1063. To make things easy. No hold it’s about 14 hours. Plenty O time, if your clay is fairly clean and doesn’t need such a long bisque, you could speed things up after testing a faster schedule.

Should I average the char out for glaze firing as well?

 

1 hour ago, Bill Kielb said:

I would not save any old elements except to cut up and use as inserts for hanging loops. I had a gal that would always take scraps and  embed them for her midfire  wall tiles for hanging.

Nice! I remember some "special" wire that we used to hang beads from and to make loops when I was a kid and I was saying to my husband I wonder if I can use this for that. I thought about just keeping the ends of the new heating element that we cut off. Can I use the old element too? Just sand it or something to get the oxidation off?

 

Thanks!

[Bill Kielb]

26 minutes ago, feistyfieryceramics said:

Should I average the char out for glaze firing as well?

Yes I would, that is the firing you really want to dial in your cone for consistency so that Last 100c degrees is important for consistency. Glaze fires range from  approximately 4 hours to 8 hours so maybe a rate that gets a 7-8 hour firing should be fine to start and you can speed things up as your glaze look will tolerate.

26 minutes ago, feistyfieryceramics said:

Can I use the old element too? Just sand it or something to get the oxidation off?

Yes you can as long as they are not so old that they are super brittle. I would only save her several 2’  pieces of relatively flexible old elements. Some elements become so brittle that removing them 2” at a time is a thing. She would generally cut and use single loops for a small hook with a decent imbed depth but when she needed a bigger loop we just showed her how to heat with a torch (red hot) and straighten / bend to the size she needed with long nose players. It’s sounds difficult but is super easy. She  would wire brush them shiny before sale as they will corrode and darken a bit in the firings. 

Once a wire is placed,  generally no more cold bending, so placing them as a finished loop is a thing.

Here is an elephant character she gave me. The loop of element forms the tail.  Interesting in that she just glazed it as well and it still looks good - very clever!

[feistyfieryceramics]

19 hours ago, Bill Kielb said:

Here is an elephant character she gave me. The loop of element forms the tail.  Interesting in that she just glazed it as well and it still looks good - very clever!

@Bill KielbWow! Yeah. I didn't register that was the metal. It's cool that the glaze stuck.  A new fun thing to experiment with!

I ran the kiln empty last night and I was perfect! I'll do a bisque firing tonight and monitor the end of it to check the cones.

Thank you all fo your help!

[Babs]

Not techical, but your 2 increases then soak can simply be...

Say 100C /hr to 200C

100C/hr to 600C 

Soak 00.00   i .e. none

Then 150C/hr to 700C

150C/hr to 750C

Soak 00.15 (15mins)

Basically dividing your schedule into more sections of ramp than "needed" but fits the program.

And so on.

How many ramps available?

[feistyfieryceramics]

On 3/22/2021 at 1:01 AM, Babs said:

Not techical, but your 2 increases then soak can simply be...

Say 100C /hr to 200C

100C/hr to 600C 

Soak 00.00   i .e. none

Then 150C/hr to 700C

150C/hr to 750C

Soak 00.15 (15mins)

Basically dividing your schedule into more sections of ramp than "needed" but fits the program.

And so on.

How many ramps available?

@Babs

I can have a delayed start, 2 ramps, then a hold, then a slow cool. Or at least I assumed it had to be used as a slow cool as that is what the sort of illustration shows. I have never tried to turn the slow cool into another heating ramp but now I am curious to try. But then that's it. That's all I can program.

[Babs]

Ok makes it less flexible for sure!

Bisque

100C/hr to 600C

150/hr to end temp

Hold 10mins.

(1063C is pretty high, what coneis that?)

[Bill Kielb]

1 hour ago, Babs said:

(1063C is pretty high, what coneis that?)

Cone 04

[Babs]

On 3/23/2021 at 11:25 PM, Bill Kielb said:

Cone 04

Ok then that is good!

[oldlady]

caitlin, is there some reason you do not list your location in your avatar?  your supplies come from germany, the machinery you show was made in england, is it such a secret where you live?

[feistyfieryceramics]

On 3/24/2021 at 3:48 PM, oldlady said:

caitlin, is there some reason you do not list your location in your avatar?  your supplies come from germany, the machinery you show was made in england, is it such a secret where you live?

I am living Sweden but I am American.

[feistyfieryceramics]

@Bill Kielb @neilestrick

The kiln is working great! I've been running it pretty much non-stop since it was fixed to catch up on the firing!

 

I have a questions. Generally the brick is in good shape but...

Before we vacuumed the kiln and installed the new elements, I removed bits of loose insulating brick so they wouldn't get sucked into the vacuum. Each piece is pretty small, but in two places the cumulative missing piece is big and so the element channel is sort of missing there. I am afraid that as the heating element ages and get longer, they will pop out and stick to the pottery and then burn out. So I am wondering can I make element pins from my old elements to hold the new elements in the channel (or what used to be the channel)? 

 

Thanks!

Caitlin

[neilestrick]

3 hours ago, feistyfieryceramics said:

So I am wondering can I make element pins from my old elements to hold the new elements in the channel (or what used to be the channel)? 

 

If it'a a big enough chunk, use pins to hold the piece of brick in place. Otherwise just pin the element. You can try to use your old element to make pins, but old elements are usually too brittle to straighten out. If you've got some of the straight pigtail end, that would probably be easiest.

[feistyfieryceramics]

On 4/5/2021 at 2:33 PM, neilestrick said:

If it'a a big enough chunk, use pins to hold the piece of brick in place. Otherwise just pin the element. You can try to use your old element to make pins, but old elements are usually too brittle to straighten out. If you've got some of the straight pigtail end, that would probably be easiest.

Thanks!

[Min]

I've found staples hold better than pins. (first image)