# Conveyor Furnace



## Green CTE2 (Jan 2, 2009)

A buddy of mine purchased a conveyor furnace for his business. The only info he was given for it was 33kw, 230v, 3p. He does have a 3p panel 120/240. there's no nameplate on the furnaces themselves. Any opinions on how to find the current breaker/wire size?


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## CTshockhazard (Aug 28, 2009)

Green CTE2 said:


> Any opinions on how to find the current breaker/wire size?


I would use math and table 310.16 & article 240.4 in the code book.

Do that, post back, and someone is likely to tell you if it's correct.:thumbsup:


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## Dennis Alwon (May 9, 2009)

In a simple single phase you would take your watts and divide by your voltage to get your amperage. But since this is 3 phase you divide by your voltage times the sqrt 3. 

Since this is a heater you must also multiply your amperage times 125% plus you need to add the current of the motor. Since there is no name plate you may have to open the furnace up and find the info on the motor itself.


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## RIVETER (Sep 26, 2009)

*Conveyor furnace*



Green CTE2 said:


> A buddy of mine purchased a conveyor furnace for his business. The only info he was given for it was 33kw, 230v, 3p. He does have a 3p panel 120/240. there's no nameplate on the furnaces themselves. Any opinions on how to find the current breaker/wire size?


 What is a conveyor furnace?


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## Green CTE2 (Jan 2, 2009)

*Conveyor furnace*

the paperwork says "these furnaces are capable of performing a wide variety of apps including annealing, brazing, glass to metal sealing, normaling and sintering"


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## Green CTE2 (Jan 2, 2009)

so if it is 33kw/240= 137.5/ 3sq= 45.83amp

46 x 125%= 57.5amp

so would that mean id use a 60amp breaker and #6 thhn...


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## jw0445 (Oct 9, 2009)

Your getting there. The square root of 3 is 1.73


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## CTshockhazard (Aug 28, 2009)

kW / (V x Sq Rt of 3) = A 

A x 1.25 = circuit min. ampacity


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## Green CTE2 (Jan 2, 2009)

so your saying 80amp x 1.25 = 100amps per furnace???


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## CTshockhazard (Aug 28, 2009)

Green CTE2 said:


> the paperwork says "these furnaces are capable of performing a wide variety of apps including annealing, brazing, glass to metal sealing, normaling and sintering"


After re-reading this I'm not so sure that the 125% that applies to fixed electric space heating would apply here.

But the 125% would apply if this load is expected to run for 3 or more hours at a time.


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## Green CTE2 (Jan 2, 2009)

so what jw 0445 is saying it would be 137.5 amps divided by 1.732? = 80amps?


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## user4818 (Jan 15, 2009)

You do know an E1 license is required to do this job, right?


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## Dennis Alwon (May 9, 2009)

Green CTE2 said:


> so your saying 80amp x 1.25 = 100amps per furnace???


That is almost the minimum but you also have to include the motor load.


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## jw0445 (Oct 9, 2009)

100 amps is your answer when you add 25%. #2 cu. thhn


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## Dennis Alwon (May 9, 2009)

jw0445 said:


> 100 amps is your answer when you add 25%. #2 cu. thhn


Every one is forgetting the motor. That will bring it over 100 amps.


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## CTshockhazard (Aug 28, 2009)

Dennis Alwon said:


> Every one is forgetting the motor. That will bring it over 100 amps.


Dennis, I realize it's being called a conveyor furnace, but I haven't seen any mention of a motor.

I'm picturing a piece of equipment that through electric heating can braze or anneal, etc, something that is passing through it on a conveyor.


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## Dennis Alwon (May 9, 2009)

CTshockhazard said:


> Dennis, I realize it's being called a conveyor furnace, but I haven't seen any mention of a motor.
> 
> I'm picturing a piece of equipment that through electric heating can braze or anneal, etc, something that is passing through it on a conveyor.


So the conveyor is not part of the equipment? I guess that's possible. I would have thought there was a motor somewhere but maybe not.


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## brian john (Mar 11, 2007)

Dennis Alwon said:


> So the conveyor is not part of the equipment? I guess that's possible. I would have thought there was a motor somewhere but maybe not.


The conveyor furnaces I worked on had a separate feed for the motor.

Heater was one load, motor another load, though like everything this is equipment specific.


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## Green CTE2 (Jan 2, 2009)

I guess that is one of the problems, whether or not it has a motor....


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## wildleg (Apr 12, 2009)

is it wise to install a furnace like that if it doesn't have a label ? If the furnace (for whatever reason) kills someone, is it going to be criminal negligence to the person who hooked up an unlabeled and therefore possibly unlisted appliance ?


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## bobelectric (Feb 24, 2007)

So your "Buddy" bought this unit with out any thought?


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## LGLS (Nov 10, 2007)

Yep. A "buddy" of his purchased this piece of industrial manufacturing equipment, and it has nothing to do with the OP who only wants to help his... "buddy."


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## nitro71 (Sep 17, 2009)

Nameplate has enough information on it. Just because it doesn't hold your hand doesn't mean it's not safe.


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