Skutt KS-1027 section removal

[marymae]

Hi,

I purchased a used Skutt KS-1027.  The previous owner switched pugs from a V208 to a V240. ( I don't really know what that means but he was able to plug it into his dryer plug) After plugging it in at home, my breaker tripped when the switches were turned to HI.

The KS-1027 has 3 sections.  I want to take out the lower section so there isn't as much power going to the kiln.  Is that doable and would it help my problem?

Thank you!

[neilestrick]

You cannot run that kiln on a clothes dryer circuit. There are two issues to deal with when hooking up a kiln, voltage and amperage. The electrical service in homes in the US is 240 volts. In most commercial spaces it is 208 volts. The elements in the kiln are wound to work properly on whichever service you have. You get the correct elements depending on your voltage.

As for amperage, the breaker in your breaker box, and the wire going from the box to the kiln, must be able to handle the amperage draw of the kiln. Smaller kilns pull lower amperage, bigger kilns pull more. Everything from the breaker box to the kiln must be able to handle the amperage draw of the kiln, plus 25% to meet code. A Skutt KS1027 pulls 48 amps, so it has to be on a 60 amp breaker, and have at least 6 gauge wire from the breaker to the kiln. If the previous owner changed out the plug to work on a clothes dryer, then he probably created a dangerous situation because most clothes dryers run on a 30 amp circuit. If he put a 30 amp plug on the kiln and ran it on a 60 amp circuit, then he was lucky it didn't overheat and cause a fire. Did he just change out the plug, or the whole power cord, too?

As for you removing a section of the kiln, yes, it is possible, however you'll have to put different elements in it. You'd be turning it into a KS1018, which uses different elements than the 1027. The 1027 elements would be under-powered since the ratio of wall area to lid/floor area are different The 1018 pulls 40 amps, so it needs to be on a 50 amp breaker.  The biggest kiln that could run on a 30 amp clothes dryer would be a kiln that only pulls 24 amps, which would be much smaller than what you have.

[marymae]

Thank you for your reply!  I really appreciate your knowledge. 

The previous owner change the power cord and all the elements but he was using all 3 sections so I don't know if they would be the right ones for a 2 section kiln.  Is there a way to see what kind of elements he put it?  I tried contacting him but was not successful.  

We took out the bottom sections and my electrician put in a new breaker.  We tested the kiln and it heated up but the power light did not turn on.  Im not sure why.  We let it heat on HI for over and hour  without the breaker tripping.  I will check the elements and if they are the right ones, I think I should be good to go?

 

 

[neilestrick]

1 hour ago, marymae said:

We took out the bottom sections and my electrician put in a new breaker.

So you're using two sections, the kiln is 18" deep inside? What size breaker did they install, and what size wire is going from the breaker to the outlet? What is the amperage rating of the outlet? It should say on it. Post a picture of the outlet if you need to.

1 hour ago, marymae said:

The previous owner change the power cord

What type of cord did he install? Post a picture of the plug and cord.

1 hour ago, marymae said:

I will check the elements and if they are the right ones, I think I should be good to go?

You need to measure the resistance of the elements using a multimeter. From there we can figure out everything else.

Do not run the kiln until we get this all straightened out. Without knowing the amperage draw of the kiln we don't know what size everything else should be.

[Dick White]

Several concerns about the current state of affairs - you took out the bottom section, which changes the amperage draw from 48 amps to 31 amps, assuming the elements are the correct ones for a 240V 1027 kiln. That requires a 40 amp circuit, including the associated wiring. You said you were using a dryer circuit, which is typically a 30 amp circuit. You say the electrician changed the circuit breaker. Changed it to what amperage? If the sparky put the required 40 amp breaker on an existing 30 amp circuit, you need a new sparky and hope your homeowner's insurance is paid up.

Regarding the kiln itself, the design of Skutt kilns places hotter elements in the top and bottom rows to compensate for heat losses through the lid and base. The middle 4 rows of elements are cooler because less heat is need in the middle compared to the top and bottom. By removing the bottom section, you have eliminated that one element at the bottom that needs to be hotter. It may have somwhat unbalanced heating now. Furthermore, though it is now the size of a 1018 kiln, kilns are designed with optimal ratios of heat to kiln surface area. The standard 1018 kiln needs 39 amps to perform up to maximum expectations. Yours now has only 31 amps. Thus, you will probably be limited to cone 6 at best.

[marymae]

Thank you for your reply!  

The previous owner change the power cord and all the elements but he was using all 3 sections so I don't know if they would be the right ones for a 2 section kiln.  Is there a way to see what kind of elements he put it.  I tried contacting him but was not successful.  

My electrician put in a new breaker for me today.  We tested the kiln and it heated up but the power light did not turn on.  Im not sure why.  We let it heat on HI for over and hour  without the breaker tripping.

Here are the photos of my kiln hook-ups.  I will have to get a multimeter to check my elements.  I will only be using the top and middle sections, 18" deep.  I only fire to ^6.  You are so kind to help me!  Thanks again!!

 

[neilestrick]

Edited

Best bet to get this kiln running properly and safely is to start over with the correct elements. You'll need elements for a KS1018. There are two types of elements for that kiln, 2 top/bottom and 2 center, total of 4. Measure the thickness of the bricks in your kiln, they will be either 2.5" or 3". Get elements for the correct brick thickness or they won't fit correctly.

You'll need to put a new power cord on the kiln. Get it from Skutt. It'll be a 50 amp cord with a NEMA 6-50 plug.

Expect to spend about $400 for kiln parts.

With the correct elements the kiln will pull 40 amps. Codes says that the breaker must be 25% greater than the draw of the kiln, so it will need a 50 amp breaker. All wiring from the main panel to the sub panel by the kiln and from the sub panel to the outlet must be at least 6 gauge wire. Larger if needed for voltage drop.

You'll need a new outlet to match the plug, NEMA 6-50.

Get a good electrician who can do this right so you don't burn down your house.

[marymae]

The electrician said I only have 100 amps for my whole house/garage.  If this is true will there be enough amps for my kiln and everything else in my house/garage?

 

Edited February 22, 2023 by marymae
clarification of my question

[High Bridge Pottery]

Isn't 25% greater than 30 amps 37.5 amps? I know it doesn't match the kilns amps but it seems within the code and the electrician is oblivious to how much power the kiln is using?

[neilestrick]

1 hour ago, High Bridge Pottery said:

Isn't 25% greater than 30 amps 37.5 amps? I know it doesn't match the kilns amps but it seems within the code and the electrician is oblivious to how much power the kiln is using?

You're right. My bad. I was in a rush. Edited to avoid confusion.

But I'd like to know why he wired it up to match the plug when that doesn't match the info on the serial plate. Trusting the previous owner who changed the power cord?!? I don't think there's any way that kiln was pulling only 30 amps before. That would be like turning off an entire ring. It would maybe hit low bisque temps at best.

[neilestrick]

3 hours ago, marymae said:

 Will this even work?

That's a question for your electrician. It depends on what else is hooked up to the panel.

[Dick White]

1 hour ago, High Bridge Pottery said:

Isn't 25% greater than 30 amps 37.5 amps? I know it doesn't match the kilns amps but it seems within the code and the electrician is oblivious to how much power the kiln is using?

There are a number of inconsistencies here. The now-2-section kiln, if still containing the proper elements from when it was a 3-section kiln (which we don't know), would be pulling 31 amps (which is insufficient for the volume of the kiln and will have unbalanced heating, but that's not our problem; it's only our problem when our tax dollars are spent on a fire department call...). Under the 125% rule (which the electrician may or may not be aware of, some are, some aren't until pointed to that page in the code book), that would require a circuit of 38 amps, or rounding up to the next available breaker size, 40, which the picture shows  was used and is correct. The plug and receptacle shown in the pictures is a standard 30 amp set. The power cord shown in the picture appears to be the original cord but with the original 50 amp plug cut off and replaced by a 30 amp dryer plug from the hardware store. That alone is insufficient for the kiln (and I can't imagine how the previous owner ran the whole kiln on that...). In the N. American electrical inventory, there is a 40 amp breaker, but there is no standard 40 amp plug and receptacle; it skips from 30 to 50 amps. Thus, the plug needs to be a 50 amp (6-50) set while the breaker and wiring would be 40 amp material (including the black cable coming in from the left that goes back to the main panel, which in N. American standard cable colors is 8 ga., suitable for 40 amps) . Let's just assume the electrician also properly used 40 amp wire inside the metal flex cable in that installation, but set an insufficient 30 amp receptacle to avoid having to repair the existing power cord's currently insufficient plug? Just too many unknowns.

Edited February 22, 2023 by Dick White
technical adjustment

[neilestrick]

1 hour ago, High Bridge Pottery said:

Isn't 25% greater than 30 amps 37.5 amps? I know it doesn't match the kilns amps but it seems within the code and the electrician is oblivious to how much power the kiln is using?

I was just thinking about this some more- if it was flipping the 30 amp breaker then we know it was pulling more than 30 amps, so that plug and outlet should not be used.

[neilestrick]

4 minutes ago, Dick White said:

(and I can't imagine how the previous owner ran the whole kiln on that...).

I once worked on a 48 amp kiln that had been on a 40 amp breaker for years, until the breaker died.

Not sure how they got a 30 to work, though. They maybe changed the breaker to a 50 and had all that #10 wire running 48 amps.

[marymae]

The breaker did not flip when we reduced the size of the kiln from 3 to 2 sections.  Does that make a difference?   The electrician admitted he has never worked on a kiln before so maybe he felt intimidated.   He is a 68 year old man who has been an electrician all his life.  I thought he would have an idea. 

[Dick White]

18 minutes ago, neilestrick said:

I once worked on a 48 amp kiln that had been on a 40 amp breaker for years, until the breaker died.

Not sure how they got a 30 to work, though. They maybe changed the breaker to a 50 and had all that #10 wire running 48 amps.

And didn't have a fire? Or at least toasted wires?

[High Bridge Pottery]

I wasn't trying to claim it is safe to fire the kiln or good of the electrician to miss the inconsistencies just that a 30 amp socket/plug on a 40 amp breaker fits the code.

[Dick White]

20 minutes ago, marymae said:

The breaker did not flip when we reduced the size of the kiln from 3 to 2 sections.  Does that make a difference?   The electrician admitted he has never worked on a kiln before so maybe he felt intimidated.   He is a 68 year old man who has been an electrician all his life.  I thought he would have an idea. 

Still assuming that the elements are the ones specified for the original configuration, 2 things are possible: 1) The elements are sufficiently worn now that they are pulling less than the specified amperage, and that would get it slightly below the 30 amp breaker. But when the elements are completely worn and replaced, it would be above the breaker size. 2) Breakers are designed to carry only 80% of the rated load for long periods of time, hence the 125% rule for continuous loads of 3 hours or more. The 30 amp breaker likely did not trip because it wasn't overloaded for long enough, but it probably would have in the middle of a firing.

[Dick White]

10 minutes ago, High Bridge Pottery said:

I wasn't trying to claim it is safe to fire the kiln or good of the electrician to miss the inconsistencies just that a 30 amp socket/plug on a 40 amp breaker fits the code.

It is true that 48 amp kilns are built with 50 amp plugs/receptacles on 60 amp circuits. So, yes, a kiln drawing less than 30 amps could use a 30 amp plug on a 40 amp circuit. But this kiln is likely pulling more than 30 amps (though we don't actually know, just doing the math from factory spec sheets), so the 30 amp plug is insufficient.

[neilestrick]

42 minutes ago, marymae said:

The breaker did not flip when we reduced the size of the kiln from 3 to 2 sections.  Does that make a difference?   The electrician admitted he has never worked on a kiln before so maybe he felt intimidated.   He is a 68 year old man who has been an electrician all his life.  I thought he would have an idea. 

It all has to be wired up according to the actual amperage draw of the kiln, which we don't know at this point.

Most electricians don't know anything about kilns. They are unusual compared to most appliances they work on. Typically they defer to what the serial plate says.

4 hours ago, neilestrick said:

Best bet to get this kiln running properly and safely is to start over with the correct elements. You'll need elements for a KS1018. There are two types of elements for that kiln, 2 top/bottom and 2 center, total of 4. Measure the thickness of the bricks in your kiln, they will be either 2.5" or 3". Get elements for the correct brick thickness or they won't fit correctly.

You'll need to put a new power cord on the kiln. Get it from Skutt. It'll be a 50 amp cord with a NEMA 6-50 plug.

Expect to spend about $400 for kiln parts.

With the correct elements the kiln will pull 40 amps. Codes says that the breaker must be 25% greater than the draw of the kiln, so it will need a 50 amp breaker. All wiring from the main panel to the sub panel by the kiln and from the sub panel to the outlet must be at least 6 gauge wire. Larger if needed for voltage drop.

You'll need a new outlet to match the plug, NEMA 6-50.

See above. This is what is needed to make the kiln work for you with two sections. Your electrician will be able to tell you if you've got enough power to run a 40 amp kiln or not.  If not, then look for a kiln that only pulls 24 amps, as you can put that on a 30 amp circuit. Many 18"x18" interior kilns are 24 amps.

[marymae]

You guys really put your time in on this one!  Thank you, even though it's not what I was wanting to hear! 

[Dick White]

3 minutes ago, marymae said:

You guys really put your time in on this one!  Thank you, even though it's not what I was wanting to hear! 

We'd rather keep you in the group to talk about your pottery than see you living in a motel fighting with the insurance company after a fire.

[neilestrick]

46 minutes ago, Dick White said:

It is true that 48 amp kilns are built with 50 amp plugs/receptacles on 60 amp circuits. So, yes, a kiln drawing less than 30 amps could use a 30 amp plug on a 40 amp circuit. But this kiln is likely pulling more than 30 amps (though we don't actually know, just doing the math from factory spec sheets), so the 30 amp plug is insufficient.

I've spoken to L&L about this before, because I occasionally run into an electrician who will not use the 50 amp cord on a 60 amp circuit. L&L said this is sort of a gray area, and all the 48 amp kilns get UL listing with the 50 amp cord because the cord uses 6 gauge wire and can handle the 60 amps should it need to. If you look at the smaller kilns made by L&L and Skutt that pull 20 amps, they size the power cord for the 30 amp breaker, not the 20 amp draw. 

[Bill Kielb]

3 hours ago, High Bridge Pottery said:

sn't 25% greater than 30 amps 37.5 amps? I know it doesn't match the kilns amps but it seems within the code and the electrician is oblivious to how much power the kiln is using?

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.

Edited February 22, 2023 by Bill Kielb

[marymae]

1 hour ago, neilestrick said:

It all has to be wired up according to the actual amperage draw of the kiln, which we don't know at this point.

Most electricians don't know anything about kilns. They are unusual compared to most appliances they work on. Typically they defer to what the serial plate says.

See above. This is what is needed to make the kiln work for you with two sections. Your electrician will be able to tell you if you've got enough power to run a 40 amp kiln or not.  If not, then look for a kiln that only pulls 24 amps, as you can put that on a 30 amp circuit. Many 18"x18" interior kilns are 24 amps.

So really, making this kiln a 1018 isn't saving much in amps compared to the 1027.  True?