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Cress kiln turned off before cone in sitter melted


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I am new to using manual kiln sitter kilns.  Recently I purchased from the original owner a Cress B-1411 built in 1980 it is 115v 20 amps.  She said she purchased it new and only fired it twice.   I had it wired into the same 60amp circuit as my 240V Skutt knowing that I could only fire on kiln at a time.  I started a test fire a couple days ago but had to end it as I ran out of time all elements were glowing.  Today I placed a new cone 5 bar in the sitter put it on low 2hr, everything was good...then medium 2hr.... still good then turned it up to high my hope was it take an additional 4 hrs though I had no clue as it is the first fire.  Short of the four hour mark the lights were no longer on and the elements were not red the cone bar had not melted I snapped it making the sitter trigger off, and my witness cones 4, 5, 6 had not melted and barely changed color, still brittle.  I could not restart I held the sitter and pushed the plunger again and nothing...kiln was still hot but not scorching, was it just too hot?  No thumbwheel  just two dials with settings slow, medium, high pic below.  It did not trip my circuit my Skutt still registered the air temp so it had power. Any ideas?  Thanks in advance.

 

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When you say you held the sitter, do you mean you lifted the claw part, or the hammer that flops down? If you were lifting the claw part at the top that’s held in place by the cone or bar, that’s not the part that actually turns it on or off. It’s the hammer/weight at the bottom that does the falling.  If you lift that part up again and push the button in firmly, and lower the weight again very carefully it should stay on. You’ll have to turn it off again yourself: you have no backups at that point.

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Before we get to why the kiln turned off early (and it may be related to this), can you please explain how this kiln is wired into the same 60 amp circuit as your Skutt? Is it on its own properly sized breaker or running on the 60 amp breaker?  Post a picture of the serial plate with the voltage and amperage info, or at least let us know what it says, including max temp rating. The reason I ask is because this kiln looks to be too large to be running on 115 volt 20 amps if it's a pottery kiln. Kilns must be on their own breaker that is rated at 25% greater than the draw of the kiln, so it can't run on the same circuit. Give us the kiln info and we'll figure out what's going on here. Could be a sitter issue, but we need to make the wiring setup is safe.

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23 minutes ago, whirlygigceramics said:

the electrician direct wired it like the skutt rather than keeping the plug

Thanks for the photo. Is it on its own breaker? Should be on a 25 or 30 amp breaker.

Have you confirmed with Cress what the max temp rating is for the kiln? I can't find any info for it on the Cress web site. I'll call them and see if you haven't. For its size and voltage it may only be rated for cone 6 or less, which would not be ideal for glaze firing to cone 5. You'll only get about 30 firings from a set of elements.

As for the power and the Sitter, when you push in the power button, does it stay in like it's supposed to, or just pop back out? If it's staying engaged, but there's no power to the elements, then you've likely got a fried connection in there somewhere. It could be a wiring connection in the box, or it could be a break in an element depending on how it's wired. If the light isn't coming on, then it's probably a wiring connection, or even a fried light (but you'd still have power to the elements even if the light is dead). It's also possible that the contact plates in the sitter are corroded. I'd unplug the kiln and open the box and look for any obvious issues. Also possible that the breaker is dead. If there's nothing obviously wrong when you look in the box, you'll need to trace the power path with a meter to see where it dies. You might need an electrician or kiln tech for that if you're not comfortable working with live electricity.

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@neilestrick it share a 60amp breaker with the skutt but only one kiln is fired at a time. Had my skutt wired with new breaker in 2019 and the skutt has power. The woman I purchased it from says it is rated cone 6. That would be rare that I would use it at that cone but I figured to test it I would see if it would reach temp. When I push the plunger it does stay in then I turn the dials I can hear them click once but no illumination to the little knobs and no heat to elements 

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2 hours ago, whirlygigceramics said:

This is what the wiring looks like. Far left is the skutt power cord, smaller flat grey cord is the Cress. Of course both kilns cannot be fired simultaneously. 

@Bill Kielb is this allowed? Doesn't code require that the 240 volt line be the only thing on that breaker?

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1 hour ago, whirlygigceramics said:

When I push the plunger it does stay in then I turn the dials I can hear them click once but no illumination to the little knobs and no heat to elements 

Those are infinite switches, with timers in them that cycle the power on and off. Depending on how they're set up, the lights may only go on when the switch is sending power to the elements. Do you get any heat if you turn them on high/ all the way up? Also make sure that the knobs are in the correct position, like when the knob is pointing to off then the switch is actually in the off position. Some knobs can be mounted in various positions, not just the correct one.

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@neilestrickhmmm interesting that it only lights when the cycle on. Now this may sound dumb...but...from the off position I assume you turn the black plastic knob  toward low to high. To turn it off does it go high back to low then off or can you go from high continuing to  turn left beyond high to off.   How would I know true off position. Here is a pic in off I only have one black plastic knob currently the electrician broke my other one 

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3 minutes ago, whirlygigceramics said:

To turn it off does it go high back to low then off or can you go from high continuing to  turn left beyond high to off.

Usually you can go from High directly to Off. So from Off you should feel it click into the Low position, or if you turn the other way from Off it'll click into the High position. Between Low and High there should be no resistance, just a smooth rotation of the knob.

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1 hour ago, whirlygigceramics said:

From off it clicks then moves freely.

As long as you're certain of the Off position you should be good. On High it should turn the elements on full power. You get nothing from either switch? What size fuse is that in the breaker box? Have you tried swapping it for one you know is good? If he put a 20 amp fuse in there then it may have blown. It should be 25 or 30 amps.

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Ahhh that little glass fuse says 20a on it. I honestly don’t remember/ know if they added that little fuse thing or if it was there since I had my skutt wired up. I’ll find out if this electrician put it in that little fuse would need to be at least 60a to handle the skutt or on 30a fuse for the Cress and the skutt a 60a fuse since there are two fuse slots

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2 hours ago, neilestrick said:

@Bill Kielb is this allowed? Doesn't code require that the 240 volt line be the only thing on that breaker?

Definitely not the best ever but looks like they brought in 240v, a neutral and ground. So a bit messy and what looks like lamp cord feeding 120 v. Not the best ever as well as the two pole fuse holder with one side used as well as the load side buss from the 240 v disconnect to the 120 volt cartridge fuse. A bit home made IMO. My thought is the 120v  leg is protected by the fuse.

Edited by Bill Kielb
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Electrician just told me skutt not wired into fuse thank goodness but the power cord to Cress is not rated for  a 30a fuse and would melt before a fuse that big would trip. He will come look. Maybe it needs a hefty cord. I’d be happy to get this kiln to go to cone 04 and for low fire glazes, and to do luster and decal that was the main purpose. Just thought why not push it cone 5 in test  but Cone 5 not a necessity 

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2 hours ago, whirlygigceramics said:

Electrician just told me skutt not wired into fuse thank goodness but the power cord to Cress is not rated for  a 30a fuse and would melt before a fuse that big would trip. He will come look. Maybe it needs a hefty cord. I’d be happy to get this kiln to go to cone 04 and for low fire glazes, and to do luster and decal that was the main purpose. Just thought why not push it cone 5 in test  but Cone 5 not a necessity 

That's not the best cord IMO. By code, kilns need to be on a circuit that is rated for 25% greater than the draw, but no more than 50% greater. So your 20 amp kiln should be on a 25 or 30 amp breaker. That means a power cord that can handle that, too. A 30 amp cord and 30 amp outlet would be best, with either a 25 or 30 amp fuse. Ideally you would install a 60 amp sub panel, then pull the line for each kiln off of that, each with its own properly sized breaker.  It's a bit shim-sham the way it is now, and I would be surprised if it would pass inspection. It's a perfect kiln for low fire work, you just need to get the wiring/fuse situation worked out.

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4 hours ago, neilestrick said:

be surprised if it would pass inspection.

Turning the disconnect into a fixture / raceway/ whatever you call it with the addition of the fuse block most likely would not be allowed. Economy way to do this in the old days would likely be as below. Plug fuse protected switch mounted in exterior rain tight surface mount box piped and wired to disconnect. Seal tight from box to new kiln within six feet of disconnect. Some solution like this where all rated parts, wire, appropriate interior volume / fill.

Second thought might just need a rated fused disconnect, these plug  fuse switches probably aren’t rated high enough.

 

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Edited by Bill Kielb
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