Electrical fire smell in a newly installed used Cress FX1814 P- 19 amps kiln

[Ksmith]

I have a Cress FX1814 P- 19 amps.

Question: I tried to bisque fire a kiln full of pottery this week.  I just had 220 installed at my new place. The first bisque fire worked pretty good, but when  I walked outside to check on the kiln after 4-5 hours of the 2nd bisque firing, the whole garage smelled like an electrical fire. It was a strong smell. No smoke though. I turned off the kiln and the next day when I opened and unloaded the kiln, each piece had smoke damage.  The shelves had smoke damage too. No evidence from where though- I opened the control box and nothing seemed amiss. The wire,  electrical box and outlet seemed fine too. Any suggestions as to what may have  caused the smoke/electrical smell in the kiln?
 

For some  extra info- I bought it “new” on Craigslist in 2018, but it was built in 1994- when I bought it it was still in its original  packaging and had never been used. Over time it’s had a hard time reaching cone temp and has taken a lot longer to reach temperature (cone6). It wasn’t used for the past year and a half. The newly installed 220 has  a 30 amp breaker (20 is recommended by Cress (20 years ago)  but my electrician suggested 30) . My kiln is 19 amps. 
 

 

Edited July 11, 2023 by Ksmith
Change title

[Bill Kielb]

Post a picture of the kiln nameplate, what I can find is a kiln that draws 24 amps (if this is truly your kiln) which would require a 30 amp breaker minimum. Kilns need the breaker to be at least 125% of the load, not more than 150%. The wiring, receptacle etc… ought to be sized accordingly. For now, if it smells electrical it very likely is so finding this before operating it again is necessary. 
Your kiln is old so it was rated at 220v. Todays voltage is 240v, so it is possible it draws even more than the 24 amps which gets you into the next sized breaker at 35 amps and associated rated wiring etc…

post pictures of the name plate, cord, receptacle and wire size if you know it. Kilns are a bit specialized in their electrical requirements so better to be safe as practical with a burning electrical smell and non functional kiln.

I found a wiring diagram and looked up in an old cress manual. Both point to the need for at least a 30 amp breaker and number 8 wire (rated for more than 30 amps) I did find a website reference for 19 amps, but did not find Cress recommending this.

 

 

Edited July 9, 2023 by Bill Kielb

[Ksmith]

This is very helpful. Thank you Bill.

Haven’t  figured how to shrink photo size so I can’t post, but here’s what the plate lists:

Also, we have a new 30 amp breaker, with 8# wire. 

Cress

Model:FX1814 P

Ser 9407, volts 220AC, amps 19. 
 

The man at Cress said a 20 amp breaker is what was recommended 20 years ago (with 8# wire) but because it’s older, he says it may now be different. He also said he wasn’t a qualified electrician and couldn’t give me any additional advice. 
 

From what you said above, maybe the 30 amp breaker is too much. Would that cause electrical problems inside the kiln only and not the non kiln wiring and breaker on the outside? To note- the smoke damage was only on the inside of the kiln- pottery and shelves. 
 

I can try harder to shrink photos and post if that helps. 

[Bill Kielb]

So going by the nameplate 220/19 = 11.57 ohms and 220 *19 = 4180 watts (which ought to be somewhere on the label of the kiln) …….  so at the new residential voltage of 240v,  240v / 11.57 = 20.74 amps. Circuit breaker Minimum Size for continuous load (kiln) = 1.25 X 20.74= 25.93 amps. Maximum breaker size = 1.5 X 20.74  = 31.1amps.

So if we believe the kiln label then 30 amp breaker is fine, (20 amp breaker) would be too small.  #8 wire is good, slightly over rated so very good.

Now, please confirm your wiring is at least #10, your breaker is 2 pole 30 amps. From there, something burned so could be a loose connection at the plug, or plug to kiln or elsewhere in the kiln at element connections etc…. It’s important to find it. Since you could smell it and the kiln did not reach temperature it seems near for sure that the defect exists and must be diagnosed before you can safely move forward.

One easy way to shrink your photos (among many) is to send them by email to yourself. Usually most email programs allow you to reduce the size while attaching or before sending. Photos definitely would help folks here see things more in context.

Edited July 9, 2023 by Bill Kielb

[Pres]

@Ksmith, I believe you would get more traffic/help with your kiln problems if you would change the title to something like "Firing a newly installed used Cress FX1814 P- 19 amps kiln".

You may edit the title by clicking on the 3 dots in the upper right corner of the post. 

Good luck with your kiln problem, and Welcome to the forum.

 

best,

Pres

[neilestrick]

If there was an electrical fire in the kiln, you should be able to find melted wires/connectors in the control box. That should not cause smoke damage inside the kiln itself, though. Most likely there was something burning in the kiln.

1. Any idea how hot the kiln got?

2. Is your kiln vented?

3. Did you have any paper inside any of the pieces, or any wax resist on the work?

 

[Ksmith]

Hi Neil. I don’t have any idea how hot the kiln got. It had run for about 3 hours. I had cone 04 cones and there was no sign of them melting. There was no paper, debris or wax resist. Kiln is not vented but top hole was open. No sign of melting, faulty wires or fire of any kind. Just electrical fire smell and smoke damage on pieces. 

[neilestrick]

The smoke effect I'm seeing in your pictures is kind of what I would expect from a kiln that got hot but didn't get over 1000F. The organic materials i the clay were burning up but not burning out completely just yet. I'm not 100% convinced that there wasn't something else burning in the kiln, though. Did you use a different kiln shelf than the first firing, that maybe had something in/on it that was burning out? Where is the kiln located? Was it sitting open between firings, and perhaps some sawdust or something got into it?

Inspect all the wiring in the kiln control box, and if everything looks good, try it again. Check the power cord during the firing to make sure it's not getting hot.

[Ksmith]

There was nothing new or different except that I was firing 2 plates upright tilted against the kiln walls. I’ve done that before. I’m confused that it was such a strong electrical smell and not a “normal” burning smell. The kiln is in my garage. The back door was open. The kiln was open off and on between firings.  It was a couple of days from my previous bisque firing.

 I will recheck the wiring and retry- watching, smelling and feeling wires.  Thank you so much. 

[neilestrick]

20 minutes ago, Ksmith said:

I was firing 2 plates upright tilted against the kiln walls.

That wouldn't cause the smell, but it's not good practice. It'll cause hot spots on the elements and prevent the heat from radiating into the kiln, and you risk cracking the element grooves. Always keep pots at least 1" from the elements. A good rule of thumb is don't let anything hang over the edge of the kiln shelf.

[Babs]

Does your kiln glow red in all elements  if you were to start it up on high for 15mins? Doez the smell/ smoke  perist?

[Kelly in AK]

This is not my wheelhouse, however since I’ve personally had a kiln malfunction in an unexpected way I feel compelled to mention this:

Have you taken the outlet cover off to see how things look in the junction box?

I do suppose you have because you mentioned the wiring size, and if you mentioned doing it specifically I apologize for being redundant. An electrical smell is what it is. The nose knows.

Mine was a hardwired kiln with a junction box that was too small, overheated and caused the wires to short. Kiln, control box, all fine. Everything happened in the wall. (Wired by a licensed electrician, by the way!)

[Babs]

47 minutes ago, Kelly in AK said:

This is not my wheelhouse, however since I’ve personally had a kiln malfunction in an unexpected way I feel compelled to mention this:

Have you taken the outlet cover off to see how things look in the junction box?

I do suppose you have because you mentioned the wiring size, and if you mentioned doing it specifically I apologize for being redundant. An electrical smell is what it is. The nose knows.

Mine was a hardwired kiln with a junction box that was too small, overheated and caused the wires to short. Kiln, control box, all fine. Everything happened in the wall. (Wired by a licensed electrician, by the way!)

Good point .

I got my kiln hard wired and wiring and fuse box changed to avoid what you write about @Kelly in AK when noticing heating at power point. And so in wall and roof!

What was happening in the neighbourhood? In your roof?

The pots may be just raw like @neilestrick suggests.

Edited July 13, 2023 by Babs

[Kelly in AK]

I believe what Neil suggested about organics just burning off about the time the kiln shut off could explain it. It ran for about three hours, so seems to line up for me. We don’t often see in the kiln from 500-1000° because it’s dark and why would you? That’s what it looks like though, especially in an unvented kiln. It’s that the smell was “different” that raises alarm. And yet, just as Neil said, there could have been something foreign in the kiln burning. 

[Ksmith]

Kelly in AK, I paper tested the elements a couple of weeks ago and the coils never turned orange and it was on for 30+ minutes (with me checking every few minutes). Each coil did burn the paper though. The speed control was on normal but the % power was at 1 so maybe that’s why- it has a thumb wheel. 

[Callie Beller Diesel]

I also have a Cress with this weird setup, but a slightly different model. And mine’s from 1984, not 94.

Your infinite switch (the slow/normal/fast knob) may be aging, especially if you’re finding your kiln taking a longer time to get to cone 6. The elements being dark after 30 minutes on power level 1 are what I’d expect out of my kiln set on the lowest and slowest available. When I replaced mine a couple of years ago after I had some kiln issues, I found my kiln fired a lot faster than I had been used to. (Oddly, I didn’t have to replace my elements. Yet. Touch wood.)

There was no obvious carbon or other wear indicators on the old one when I removed it, so it could be deceiving. I also had to source an alternate infinite switch than the original, because the OG isn’t made anymore.