Kiln Overload

[Daniel Molina]

Hello to  all, I am new at this forum and not that good in English, but I will try to explain my problem:

So I bought this old Kiln (Duncan Automatic  The Pro-plus) 2 years ago, since then I use it normally but I noticed that the medium part of the kiln was not turning on while I set up to a firing, due to this, kiln was taking to long for bisque firing so I decided open the electric panel of the kiln and I found out that a cable was disconnected, I proceed to connect this cable and it solve the problem, but it brings another one, since then, all the kiln elements are turning on, but the kiln is overloading and is turning off the 50amp relay of the control panel, my kiln is 45 amp so I suppose that it should not turning off the relay. Should I bought a 60 Amp relay?

THANK YOU FOR YOUR PATIENT AND YOUR HELP!

 

[neilestrick]

Hi @Daniel Molina, welcome to the forum!

By 50 amp relay do you mean the 50 amp circuit breaker in the building's electrical panel?  Your 45 amp kiln should be on a 60 amp breaker, so that may be the problem. How long does the kiln run before the breaker trips off? If it's instantly, then something is not hooked up correctly in the kiln control box. If it runs for a short while then it's the breaker.

What voltage is your electrical service? Can you post a picture of the kiln serial plate?

[Daniel Molina]

Hello Neil, thank you for your reply, yes I was referring to the circuit electrical panel, when I turn on the kiln with all the switches on Hi-Fire, the kiln run like half of an hour before the breaker trips off. When I set all the switches in the “Ceramic” option, the kiln run like two hours before the breaker trips off.

 

My electrical service give me 220v. 
 

Here is some photos…

[neilestrick]

It's the breaker. Change it out to a 60 amp, and make sure the wiring is appropriate for 60 amps. Since your kiln is running on 220 volts, it's actually pulling closer to 48 amps. The elements are wound to work with your specific service voltage, so with elements wound for 208 volts it pulls more amperage on 220.

[Mark C.]

(and make sure the wiring is appropriate for 60 amps)  that would be #6 size copper wire feeding the 60 amp breaker box

[Daniel Molina]

3 hours ago, neilestrick said:

It's the breaker. Change it out to a 60 amp, and make sure the wiring is appropriate for 60 amps. Since your kiln is running on 220 volts, it's actually pulling closer to 48 amps. The elements are wound to work with your specific service voltage, so with elements wound for 208 volts it pulls more amperage on 220.

Thank you Neil, I just bought the 60 amp breakers, I will be telling you what happens.

 

[Daniel Molina]

17 minutes ago, Mark C. said:

(and make sure the wiring is appropriate for 60 amps)  that would be #6 size copper wire feeding the 60 amp breaker box

Both breakers are feeding by a #8 copper wire, my bad, I figured that was enough because I didn't think the kiln would go over 45 amp.

Edited March 15, 2023 by Daniel Molina

[Mark C.]

You need to rewire the box and change the breakers to make this kiln work and not start a fire.

[Bill Kielb]

In Mexico your electric ought to be a bit above 240 v for both phases and maybe even above 250v. This kiln was designed and rated at 208 volts so important to measure your actual mains voltage accurately then size wire and breaker accordingly. At 250 volts this kiln will draw over 54 amps and inNorth America require a 67 amp breaker or next size up would be 70 amps. Of course your wiring would need to be sized accordingly. You really need an electrician to size this all appropriately per your actual measured system voltage. My reading of power in Mexico is 127 volts at the receptacle and 254 volts for both phases. A 240 v rated kiln would have likely been a better fit here than a 208v kiln. You really need a decent electrician to figure this out and be safe.

So if split phase is present to match the rest of North America then measuring and knowing for sure will determine the proper breaker size.  220 v nominal is often stated and traditionally was a dated standard. Better to actually measure it.

Edited March 15, 2023 by Bill Kielb

[Daniel Molina]

10 hours ago, Bill Kielb said:

In Mexico your electric ought to be a bit above 240 v for both phases and maybe even above 250v. This kiln was designed and rated at 208 volts so important to measure your actual mains voltage accurately then size wire and breaker accordingly. At 250 volts this kiln will draw over 54 amps and inNorth America require a 67 amp breaker or next size up would be 70 amps. Of course your wiring would need to be sized accordingly. You really need an electrician to size this all appropriately per your actual measured system voltage. My reading of power in Mexico is 127 volts at the receptacle and 254 volts for both phases. A 240 v rated kiln would have likely been a better fit here than a 208v kiln. You really need a decent electrician to figure this out and be safe.

So if split phase is present to match the rest of North America then measuring and knowing for sure will determine the proper breaker size.  220 v nominal is often stated and traditionally was a dated standard. Better to actually measure it.

Thank you Bill, is very useful this information, I already contact another electrician, he will rewire to copper #6 both phases. I contract a 220 service but as you know and said sometimes I get above the estimated. For now I will not turn on the kiln till I know all the wire and breakers are the better for the power of the kiln. 

[Daniel Molina]

Thank you to all the responses, I just measure both phases and the ammeter gives me 45 amp each one, for stay more sure about my safe I will upgrade the breakers to 60amp each phase and I will have to change #8 copper to #6 copper. 

Thank you!