Pizza Oven 240 vs 208

[Buck Parrish]

A pizza oven with a name plate 29 amps 208 v. How long do you think it will last on 240 v ? It does have a motor to move it from front to back.

[iwire]

If the heating elements are not rated 240 I do not give them long and I would not hook it up.

The elements will get much hotter at 240 if designed for 208.

[infinity]

How long will it last is anyones guess. I have 240 volts supplying a single phase, 208 volt, fan driven space heater in my garage that I've used occasionally for the past 5 years and it's still working. :cool:

[Buck Parrish]

How long will it last is anyones guess. I have 240 volts supplying a single phase, 208 volt, fan driven space heater in my garage that I've used occasionally for the past 5 years and it's still working. :cool:

Does the fan go faster?

[480sparky]

Invest in a buck transformer and sleep tonight.

[LarryFine]

How long will it last is anyones guess. I have 240 volts supplying a single phase, 208 volt, fan driven space heater in my garage that I've used occasionally for the past 5 years and it's still working. :cool:
How long, and what gauge, is the garage's feeder? ;)

[infinity]

How long, and what gauge, is the garage's feeder? ;)


About 15', #6 THHN. :smile:

[iwire]

Does the fan go faster?

The fan will not run faster, the speed of AC motors has to do with frequency not voltage.

It would be the heat running so much hotter than designed that would worry me.

As far as Infinity and his garage ........ well there are a lot of things I would do at my own house I would not do for a customer.:smile: Supplying a 208 appliance with 240 is a violation and not something I would do for a customer.

[StephenSDH]

A 1KW 208 heater will produce 1.3KW at 240. The oven would heat up quicker, but once it gets up to temp it would start cycling the heaters say a duty cycle of 40% instead of 50% to maintain the same temp. The heaters would have a reduced life, but that might mean they still run for forever.

I've seen many companies do this with heaters. Very common for American manufacturers to get in European equipment with 400V heaters and run them 480V. Not saying it is code, but common.

If the equipment has motors on it, the motors windings are designed for 208 then they will likely run hotter because the electrical field generated starts to collapse.

The difference between the nominal is 15 percent, I forget the range utility companies aim for, but I think it is 10 percent.

Good luck, Steve

[72.5kv]

the Volt/Hertz ration of the motor when running at the higher voltage changes, the magnetizing current drawn by the motor goes up also which increases heating

[iwire]

The oven would heat up quicker, but once it gets up to temp it would start cycling the heaters say a duty cycle of 40% instead of 50% to maintain the same temp.

Your assuming a standard oven, the OP mentioned a motor a couple of times which makes me think pizza oven with conveyor. In this type of oven the heat stays on all the time and the pizza is run through on the belt.

If this is the case it may work fine ....... or it may produce a pizza cooked on the outside but not on the inside ..... or a hi temp safety stat may cycle on and off which is not a good thing ........ or the outer case may get hotter then designed or safe. My point is we do not know, it was not listed for this use at a higher voltage.



I've seen many companies do this with heaters. Very common for American manufacturers to get in European equipment with 400V heaters and run them 480V. Not saying it is code, but common.

Yeah, as you know manufacturers can do a lot as they have there designs tested and listed for the purpose. :smile:

The difference between the nominal is 15 percent, I forget the range utility companies aim for, but I think it is 10 percent.

Roughly 6% over,

http://i249.photobucket.com/albums/gg235/iwire_bucket/ANSIC841.jpg

but if you running at 15% over to start with that could shoot you into 21% over if the power company ends up running at the top end.

I would not violate 110.4 for a customer. :smile:

[infinity]

As far as Infinity and his garage ........ well there are a lot of things I would do at my own house I would not do for a customer.:smile: Supplying a 208 appliance with 240 is a violation and not something I would do for a customer.

I agree, I wouldn't hook this up for a client. The heater was almost brand new and the price was right, free, right out of the dumpster. Seems that someone used for one winter to heat a material locker. Spring came and out it went. I figured that since it was in my own garage I can deal with it if went up in smoke. Although it gets very intermittent use it's still going. 8-)

[iwire]

I agree, I wouldn't hook this up for a client. The heater was almost brand new and the price was right, free, right out of the dumpster. Seems that someone used for one winter to heat a material locker. Spring came and out it went. I figured that since it was in my own garage I can deal with it if went up in smoke. Although it gets very intermittent use it's still going. 8-)

Exactly how I would deal with it as well. I know a few garages with 277 volt lighting running at 240, not exactly the same but what we do at home is often different then what we would charge for. :smile:

[StephenSDH]

I would not violate 110.4 for a customer.

Neither would I, but he was asking what would happen... If I picked up a 208 pizza oven off craigslist, my wife would hate me, but I would be having yummy crispy pizza tonight.

[Buck Parrish]

Neither would I, but he was asking what would happen... If I picked up a 208 pizza oven off craigslist, my wife would hate me, but I would be having yummy crispy pizza tonight.


Exactly. he paid more for the buck booster then the used oven.

[charlietuna]

I would hook it up! There are many appliances like this. Now, if it was a printer i would recommend a buck/boost transformer. I don't think the motor,nor the elements will know the difference while operating at a higher voltage and lower current draw! MY$.02.

[charlietuna]

I would hook it up after explaining the situation to the owner! There are many appliances like this. Now, if it was a printer i would recommend a buck/boost transformer. I don't think the motor,nor the elements will know the difference in a pizza oven while operating at a higher voltage and lower current draw! MY$.02.

PS: I came across some great 175 watt MH fixtures that came out of a basketball court. Very expensive-heavy glass-designed for the purpose. One day, i had nothing to do and decided i'd hang them in the stock area of my warehouse thinking the whole time they had multi-tap ballasts! Now, i have half the original fixtures in the dumpster and the MH fixtures hanging nicely from chains, when i find out they were straight 277 volt fixtures. My shop's service was a delta, so i took that lighting circuit and put it on the highleg. Twelve years ago --no proplems.

[iwire]

I would hook it up after explaining the situation to the owner!

So as an EC you would intentionally ignore 110.4?

That surprises me, yes there are thousands of appliances that can be run on either 208 or 240 without any issues and they are labeled that way.

This appliance is labeled 208, I would not supply it 240.

[MarkyMarkNC]

If this is the case it may work fine ....... or it may produce a pizza cooked on the outside but not on the inside ..... or a hi temp safety stat may cycle on and off which is not a good thing ........ or the outer case may get hotter then designed or safe. My point is we do not know, it was not listed for this use at a higher voltage.

So you're not going to hook up a man's pizza oven because the pie may come out too crispy? :grin:

[iwire]

So you're not going to hook up a man's pizza oven because the pie may come out too crispy? :grin:

Which is a real shame as that is how I like them. :grin:

[charlietuna]

110.4 Voltages. Throughout this code, the voltage considered shall be that at which the circuit operates. The voltage rating of electrical equipment shall not be less than the "nominal" voltage of a circuit which it is connected.

I consider the word "NOMINAL" in 110.4 to mean in engineering terms:

"Real versus nominal value in engineering - a value that is used as the name for an actual value which is close but not exactly the same."

Now, taking your approach, let me ask you how many 115 volt rated appliances have you installed on 120 volt sources which actually operate at or near 130 volts? "SHALL NOT BE LESS THAN "NOMINAL VOLTAGE"". I had a code instructor years ago that always preached " knowing the code is important, but knowing why it is code is more important". His name was Mike Holt.

[LarryFine]

I don't think the motor,nor the elements will know the difference in a pizza oven while operating at a higher voltage and lower current draw! MY$.02. Sorry, Charlie. :grin: Within a certain range, a motor will use less current on a higher voltage, but the current of the heating elements will rise with the voltage.

My shop's service was a delta, so i took that lighting circuit and put it on the highleg.You mean they're connected from the high leg to the neutral? That's supposed to be a big no-no for the transformers.

[charlietuna]

True the motor will draw less current since it is doing the same amount of work.

The heating elements will produce more heat, but the thermostat will control the oven's setpoint.

"Connecting the high leg to the neutral" --now i never said that! That will cause you a major problem!

[iwire]

The heating elements will produce more heat, but the thermostat will control the oven's setpoint.

Now again your assuming a 'standard oven' which I don't belive it is. There is also no way for us to know if the unit can tolerate the elements running at a higher temp.

110.4 Voltages. Throughout this code, the voltage considered shall be that at which the circuit operates. The voltage rating of electrical equipment shall not be less than the "nominal" voltage of a circuit which it is connected.

I consider the word "NOMINAL" in 110.4 to mean in engineering terms:

"Real versus nominal value in engineering - a value that is used as the name for an actual value which is close but not exactly the same."

Right, the 'Nominal voltage' of the building is 240.

The nominal voltage rating of the oven is 208.


To connect the 208 listed equipment to a 240 nominal source is in fact a violation of 110.4




Now, taking your approach, let me ask you how many 115 volt rated appliances have you installed on 120 volt sources which actually operate at or near 130 volts?

Two problems here with your thoughts.

A 120 nominal system is still a 120 nominal system when operating at 130 volts.

The 115 volt rated motor is designed to run on a 120 volt nominal system.

http://i249.photobucket.com/albums/gg235/iwire_bucket/ANSIC841.jpg


"I had a code instructor years ago that always preached " knowing the code is important, but knowing why it is code is more important". His name was Mike Holt.

I am missing your point, the 'why' of 110.4 is clear, do not connect equipment that is listed for use at a certain voltage to a voltage system that is higher.

[charlietuna]

Bob,
What is the source of voltage regulation chart standard you posted?

I find article 110.4 very clear and have posted the meaning of the word "NOMINAL" in the eyes of engineers.

It's been common practice for years to use 208 volt motors on 240 volt circuits and vice-versa. Of course you must adjust the overloads for the voltage.

i disagree with you!

[macmikeman]

Bob,
What is the source of voltage regulation chart standard you posted?

I find article 110.4 very clear and have posted the meaning of the word "NOMINAL" in the eyes of engineers.

It's been common practice for years to use 208 volt motors on 240 volt circuits and vice-versa. Of course you must adjust the overloads for the voltage.

i disagree with you!


Dual voltage rated motors maybe, but not what you describe is ok. The other thing to consider about this is the thermostat will not operate as it should, it will most likely run at a lower temp than the setting is showing.

[iwire]

Dual voltage rated motors maybe, but not what you describe is ok.


Exactly. Thank you.:smile:

[charlietuna]

Hawaiian "brudder",
Please explain how the thermostat is effected by higher voltage?? It turns "on" and "off" the voltage to the element at the customer's chosen setpoint. True the elements will get hot faster, but thats about all.

The area of our trade where this is an issue is restaurant equipment. In my apprenticship years i worked for a contractor who represented some major equipment distributors -- we never had a problem with this issue! Equipment would come in for a new chain store with all kinds of voltages on their nameplates -- there was no shipping it back! And we serviced these same chain restaurants. In the past ten years we have had issues with copy machines not operating correctly on wrong voltage and we would install buck/boost transformers--and to tell you the truth, i always questioned if this was the true cause of the problem! And another area is in the printing industry, where many items are rated at 200 volts, not 208, but function fine on 240 volts.

[macmikeman]

Hawaiian "brudder",
Please explain how the thermostat is effected by higher voltage?? It turns "on" and "off" the voltage to the element at the customer's chosen setpoint. True the elements will get hot faster, but thats about all.

The area of our trade where this is an issue is restaurant equipment. In my apprenticship years i worked for a contractor who represented some major equipment distributors -- we never had a problem with this issue! Equipment would come in for a new chain store with all kinds of voltages on their nameplates -- there was no shipping it back! And we serviced these same chain restaurants. In the past ten years we have had issues with copy machines not operating correctly on wrong voltage and we would install buck/boost transformers--and to tell you the truth, i always questioned if this was the true cause of the problem! And another area is in the printing industry, where many items are rated at 200 volts, not 208, but function fine on 240 volts.

Not sure exactly how to explain it except I have witnessed it as well where the higher voltage messed up the temperature guage for the oven, and it read lower on the digital readout than the actual temperature that the oven got to as per a second freestanding thermostat placed into the oven confirmed. Once the voltage was bucked back to where it was supposed to be (208) everything worked fine and the elements haven't had to be changed since. The kitchen manager told me that before I converted the voltage the elements had to get replaced about every three months.

[LarryFine]

Maybe the original adjustment of the T-stat maintained the average temperature using the expected heat rise time and loss time.

A higher wattage makes for a faster rise time, but doesn't affect the loss time, so maybe the average temperature ends up higher.

[texassparky]

We have done quite a few commercial kitchens and there is a lot of kitchen equipment that the nameplate will only have 208v on it. Which I was always under the impression was still nominal for 240v. Until we started seeing equipment with tags that say "NOT RATED FOR USE ON 240V SYSTEM".

So if the nameplate isn't dual - 208 / 240 it gets a transformer in our installs.

[catchtwentytwo]

I'm sorry if I missed this in the other posts but are we talking about an electronic "thermostat" or a plain-old on/off type?