# Stove check my math



## Cletis (Aug 20, 2010)

Yo. How's my math 

Service 3 phase 240V

Stove 27kw (Continuous all day) 

#4 XHHW on 70 amp 3 pole breaker 

I had 65 amps and sized ocpd up to 70amp on #4 in MC

OCPD was about 25 ft away and sort of in sight so I don't think I need a disconnect. It's also a shunt trip which will be ordered and installed. 

Sound good or did I miss something?


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## Dennis Alwon (May 9, 2009)

Most stoves are not continuous as there is generally a thermostat involved to turn it on and off. That being the case then continuous is not necessary.

You sure this is a 3 phase 240V and not 208V


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## Cletis (Aug 20, 2010)

*yes*



Dennis Alwon said:


> Most stoves are not continuous as there is generally a thermostat involved to turn it on and off. That being the case then continuous is not necessary.
> 
> You sure this is a 3 phase 240V and not 208V


Yes, sorry, It's a commercial griddle where it runs almost continuous for cooking sandwiches, eggs, etc...like in waffle house


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## Cletis (Aug 20, 2010)

Cletis said:


> Yo. How's my math
> 
> Service 3 phase 240V
> 
> ...


Nameplate


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## Dennis Alwon (May 9, 2009)

I am asking what is the voltage on the premise not on the equipment.


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## Cletis (Aug 20, 2010)

*yes*



Dennis Alwon said:


> I am asking what is the voltage on the premise not on the equipment.


Supposedly, 240 3 phase, but yes. Sounds suspect. If 208 then 75 amps draw and I will multiply by 1.25 to get conductors and follow same rules as above.


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## Dennis Alwon (May 9, 2009)

If 208v then it would not be compliant to install the 240V unit.


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## Dennis Alwon (May 9, 2009)

Cletis said:


> Supposedly, 240 3 phase, but yes. Sounds suspect. If 208 then 75 amps draw and I will multiply by 1.25 to get conductors and follow same rules as above.


Cletis- with resistant heat the amps goes down when the voltage goes down. Thus 208v supply would draw less current than a 240V supply


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## Cletis (Aug 20, 2010)

*yeah*



Dennis Alwon said:


> Cletis- with resistant heat the amps goes down when the voltage goes down. Thus 208v supply would draw less current than a 240V supply


I know, ohms law and all that. I'll invigate tomorrow


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## Cletis (Aug 20, 2010)

*temp*

One thing I don't know is when if it is 208V 3 phase I can recalculate the resistance then how can I convert the max temp on griddle to new max and let the owner decide if he wants me to hook up or not. He already spent $7k non refundable on griddle (i'm sure griddle salesman didn't say anything about voltages to him when making the sale) .


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## Cletis (Aug 20, 2010)

*ok*

ok. I just did this real fast like in 15 min while I'm cooking and cleaning and watchng babies. Check for errors. i think I just need to convert joules to temperature now. There could be errors


P = 27000 watts = W

A = 65 = A = I

V = 240 = V = E

E = IR

Therefore 

240(1.73) = 65(R?)

Furthermore

415/65 = R

6.38 = R 

Substituting in new voltage 

208 x 1.73 = 359 

R = E/I with new voltage 

W? = A V 

65 x 359 = 23,389 Watts 

New Power is 23,389 watts 

New Ohmic Heating 

Q = I^2 x R (Q is unknown we need to find) 

Q = 6.38^2 x 65 = 2.75 x 10^6 = 275,683 joules


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## Cletis (Aug 20, 2010)

I think I"m down to Q = cm(delta)T now 

Q = Heat added 

C = specific heat

m = mass

T = Tfinal-Tinitial

any help here? anyone Chris, BBQ, B4T anyone? can you take it from here? chicken steve?


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## backstay (Feb 3, 2011)

Cletis said:


> Yo. How's my math
> 
> Service 3 phase 240V
> 
> ...


OCPD should be 90.


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## Cletis (Aug 20, 2010)

*thanks*



backstay said:


> OCPD should be 90.


yeah. I typed that in wrong. I actually already ordered a 90 amp 3 pole with 4 wire #2 Al MC already cut. Check my continuing math below

Since I used steel nichrome wires for this calc glowing red 

R ref * (1 + alpha (T -- T ref)). 
Rearranging, T ref = (1 + (alpha * 1600F -- R / R ref)) / alpha. 

Since nichrome wire's alpha is: alpha = 0.00017 / degree C (as shown in a "Colors of Heated Steel" chart) * 1 degree C / 1.8 degrees F alpha = 0.0009444 ohms / degree F change then substituting values provides: 

T ref = (1 + 0.000944 * 1600 -- (22.04 ohms / 6.38 ohms)) / 0.000944 ohms / degree F T ref = (1 + 1.5104 -- 1.565) / 0.000944 T ref = 0.946 / 0.000944 T ref = 1,002 degrees F 

Does this sound right as new temp?


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## Cletis (Aug 20, 2010)

*1.25*



backstay said:


> OCPD should be 90.


1.25 made it 81.25 amps and rounded up to a standard 90 amp ocpd


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## Dennis Alwon (May 9, 2009)

Cletis said:


> how can I convert the max temp on griddle to new max and let the owner decide if he wants me to hook up or not.


I have no idea.


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## Cletis (Aug 20, 2010)

*problem*



Dennis Alwon said:


> I have no idea.


I'll check with wolf tomorrow. Since it's a purely resistive load and the temp controls just vary the voltage as long as I size the new branch circuit conductors and ocpd correctly to altered voltage I can't see any problems realistically, maybe legally. It just won't get quite as hot.


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## Dennis Alwon (May 9, 2009)

So cletis tell me how you got Q= I^2 x R = joules when in fact it is equal to Watts


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## Cletis (Aug 20, 2010)

Dennis Alwon said:


> So cletis tell me how you got Q= I^2 x R = joules when in fact it is equal to Watts


That's just joules law. I thought that may be useful to find temp of actual griddle surface at the time of research...

More on griddles interesting 

Electric
Electric griddles are typically made of a thinner plate material than a similar gas griddle to improve the heat transfer between the bottom-mounted elements and the cooking surface. Elements used to heat the griddle are typically 4-5 kilowatt (kW) per linear foot, and made from round rod sheathed incoloy material whose geometry is designed to optimize temperature distribution across the plate. The round elements have a tangential point of contact with the griddle plate and are commonly held in place by a clamping bracket or plate. More than one element per linear foot is common, and an array of these elements is required to heat a griddle plate of any given width. Electric griddles tend to be less expensive than a gas unit of similar size, due largely to the reduced plate thickness, but also the generally lower cost of construction and reduced sophistication of most electric griddle control systems.
Though they tend to lag their gas counterparts in productive capacity, an advantage to electric griddle construction is the relative simplicity of the system that tends to limit failure modes and can result in long life expectancy for these products. The lack of hot effluent gases can significantly reduce kitchen heat loads, and reduce overall kitchen system costs by exchanging a major gas heat source for an appliance with lower hood requirements. Rates for gas and electric utilities can be used to balance the cost of ownership decision in an appliance purchase, as some geographic areas have a combination of higher natural gas prices and lower electric prices that may make electrical appliances a more effective choice.[15]
[edit]Temperature Control
Depending on the application a griddle may have either manual gas control or one of several types of thermostat in both gas and electric griddles. These control types have different performance characteristics based on the heat source, mounting, plate material and material thickness, and cannot be considered in isolation when making performance decisions.
[edit]Thermostat Controls


Thermal Cycling of Common Griddle Thermostat Controls
Thermostats are used to regulate the griddle surface around a temperature set point established by the operator. Ranges of operation can vary depending on the controls used and the construction of the griddle, but 200 to 450 °F, 93 to 232 °C is most common. Other than solid state controls, which are very sensitive across their entire range of control, snap-action and modulating (aka – throttling) thermostats have peak sensitivity across the middle two-thirds of their operating range. This can limit their overall performance at the low end of their temperature spectrum (at or below 225 °F, 107 °C). This is due to the nature of the temperature control mechanism, which consists of a fluid-filled bulb (typically an oil) connected to the thermostat control via a long narrow capillary tube. The fluid in the bulb expands and contracts with temperature, activating a control response from the thermostat. There is a time lag between sensing the temperature change from the surface of the griddle plate to the response of the fluid within the bulb, to the thermostat control and turning the heat source on or off, up or down. This lag is referred to as hysteresis, and is a primary aspect of recovery time – an important griddle performance metric.
Most commercial griddles have a single thermostat control for every 12 in (305 mm) of unit width, though some may have only one thermostat for every 24 in (610 mm). This construction technique reduces unit cost by limiting the number of expensive control elements, but at the expense of performance and zone control. The thermostat control will not react quickly (if at all) to a surface load that is not relatively close to the probe, whether embedded or bottom mounted, resulting in less control and wider temperature variations on the cooking surface. Many griddles-cooked food portions are 5 in (127 mm) or less in diameter, meaning the distance from probe to the center of a load can average up to 8 in (203 mm) – a very long distance for heat transfer in steel.
[edit]


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## hardworkingstiff (Jan 22, 2007)

Cletis said:


> I'll check with wolf tomorrow. Since it's a purely resistive load and the temp controls just vary the voltage as long as I size the new branch circuit conductors and ocpd correctly to altered voltage I can't see any problems realistically, maybe legally. It just won't get quite as hot.


It will also take longer to get to the not as hot temperature.


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## Cletis (Aug 20, 2010)

*ahhh*



hardworkingstiff said:


> It will also take longer to get to the not as hot temperature.


nice tip. It shouldn't matter though, as they fire it up when they open and just leave it on all day really, but nice to know that:thumbup:


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## Dennis Alwon (May 9, 2009)

Cletis said:


> That's just joules law. I thought that may be useful to find temp of actual griddle surface at the time of research...


You can convert watts to joules as W= joules/second or Joules = W/second




> What is the power consumption of an electrical circuit that has energy consumption of 90 joules for time duration of 3 seconds?
> P(W) = 90J / 3s = 30W


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## icefalkon (Dec 16, 2007)

Cletis, I have a question if I may...

My calculation for what your grill comes out to the same number 81.25A, bringing OCPD to 90A. Why would you go further than that? 

I'm not being factitious, I really do want to know.

Steve from NYC


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## Cletis (Aug 20, 2010)

*wired*



icefalkon said:


> Cletis, I have a question if I may...
> 
> My calculation for what your grill comes out to the same number 81.25A, bringing OCPD to 90A. Why would you go further than that?
> 
> ...


It's just the way i'm wired. I gotta try to investigate way more than needed for personal satisfaction. I know I could have just ended there but I tend to go on hours and hours into the useless details for some reason. I think it's a mental disease or something?


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## icefalkon (Dec 16, 2007)

Cletis said:


> Nameplate


Did you look at the spec sheet? I just downloaded it and it does in fact come in 208V as well.

Here is the spec book...if I can upload it...

Steve from NYC


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## icefalkon (Dec 16, 2007)

Hope that helps Cletis. Note that it says the model you have requires two electrical connections! Interesting!

Steve


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## Cletis (Aug 20, 2010)

*thanks*



icefalkon said:


> Hope that helps Cletis. Note that it says the model you have requires two electrical connections! Interesting!
> 
> Steve


thanks for locating that. Unfortunately, I think he bought slightly used and no returns.... basically, he is stuck with it


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## icefalkon (Dec 16, 2007)

Cletis said:


> thanks for locating that. Unfortunately, I think he bought slightly used and no returns.... basically, he is stuck with it


Ouch bro...that sucks! Well, what's the worst that will happen...it won't operate at full efficiency right? 

Steve


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## Cletis (Aug 20, 2010)

*yeah*



icefalkon said:


> Ouch bro...that sucks! Well, what's the worst that will happen...it won't operate at full efficiency right?
> 
> Steve


That's my theory. Is it correct?


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## hardworkingstiff (Jan 22, 2007)

I guess you could offer to install 208-volt elements (probably expensive, maybe not available).


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## icefalkon (Dec 16, 2007)

Cletis said:


> That's my theory. Is it correct?


Yeah, it will work, it just won't work at peak. Luckily it's a griddle not an oven. It would be much worse if it were an oven. The temperatures would never be on and it would be a disaster cooking with. Being it's a griddle, and will most likely be on high most of the time, it should be fine. 

Steve


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## icefalkon (Dec 16, 2007)

hardworkingstiff said:


> I guess you could offer to install 208-volt elements (probably expensive, maybe not available).


Could you imagine the cost associated with that lol. The guy bought it used...and this thing is under $4k brand new! LOL

Steve from NYC


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## Cletis (Aug 20, 2010)

*temps*



icefalkon said:


> Yeah, it will work, it just won't work at peak. Luckily it's a griddle not an oven. It would be much worse if it were an oven. The temperatures would never be on and it would be a disaster cooking with. Being it's a griddle, and will most likely be on high most of the time, it should be fine.
> 
> Steve


i'm not a cook or anything but I would think griddles need to mostly be around 250-300F ?? like 3/4 operating power. sound right ?


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## Cletis (Aug 20, 2010)

*..*

Aha 

Griddles can operate between 200° and 550°F, however, cooking temperatures *normally fall between 225° and 375°F*. Most units reach their thermostatically controlled cooking temperature in 15 to 30 minutes.

The wolf you linked maxes at 475F so all should be well


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## BBQ (Nov 16, 2010)

icefalkon said:


> Did you look at the spec sheet? I just downloaded it and it does in fact come in 208V as well.
> 
> Here is the spec book...if I can upload it...
> 
> Steve from NYC


And notice it is thermostatically controlled just as Dennis mentioned it would be.


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## BBQ (Nov 16, 2010)

icefalkon said:


> Yeah, it will work, it just won't work at peak. Luckily it's a griddle not an oven. It would be much worse if it were an oven. The temperatures would never be on and it would be a disaster cooking with. Being it's a griddle, and will most likely be on high most of the time, it should be fine.
> 
> Steve


It will be slower to heat and recover, but it is very doubtful that it could not reach temperature.


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## Cletis (Aug 20, 2010)

*Electric*



icefalkon said:


> Could you imagine the cost associated with that lol. The guy bought it used...and this thing is under $4k brand new! LOL
> 
> Steve from NYC


Let's say he is at 75% 

23,000 x 0.75 = 17,250 watts x 10 hrs day x 350 days year x 0.7 kwhrs / 1000 = 

drum roll 

$ 4,226.25 per year electrical cost


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## icefalkon (Dec 16, 2007)

Cletis said:


> Let's say he is at 75%
> 
> 23,000 x 0.75 = 17,250 watts x 10 hrs day x 350 days year x 0.7 kwhrs / 1000 =
> 
> ...


woof! that's a lot of money to fry bacon and eggs! LOL I hope this guy is successful! 

Steve from NYC


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## Cletis (Aug 20, 2010)

*new*



icefalkon said:


> woof! that's a lot of money to fry bacon and eggs! LOL I hope this guy is successful!
> 
> Steve from NYC


He is a new business and he is slammed day to night

$4,226.25 / 350 = $12 per day electric 

When you look at it that way he only needs to sell 1 extra coffee, bagel sandwich, and maybe a croissant per day to offset


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## icefalkon (Dec 16, 2007)

Yeah, I mean it's a griddle. Dennis was 100% correct. It'll take longer like BBQ said, but ultimately it'll work. This is a prime example of what happens when a client buys materials without an electricians input. You would think that he would have called your cell to make sure what the operating voltage in your area was before putting the money down. 

I hope you're gonna get free breakfasts for all this mental work on a Sunday bro! LOL

Steve from NYC


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## icefalkon (Dec 16, 2007)

Double Post


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## Dennis Alwon (May 9, 2009)

Notice also that the loads per phase on the 240V unit is lower than the 208 unit????? Also notice that the load per phase is no where near 80 amps. There are no 3 phase elements but rather single phase elements sharing 3 phases so the calc is not as simple. In fact you are way over and a 90 amp breaker is way high.


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## Cletis (Aug 20, 2010)

Dennis Alwon said:


> Notice also that the loads per phase on the 240V unit is lower than the 208 unit????? Also notice that the load per phase is no where near 80 amps. There are no 3 phase elements but rather single phase elements sharing 3 phases so the calc is not as simple. In fact you are way over and a 90 amp breaker is way high.


Then how would you calculate phase conductors? By nameplate 27kw or manual ??


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## hardworkingstiff (Jan 22, 2007)

> **NOTE: Two separate conduit connections must be made: one connection carries 16.2 KW, the other
> connection carries 10.8 KW.


I saw this note in the owners manual. Looks like you are supposed to supply 2 circuits.


http://www.wolfstoves.com/pdf/site/WEG-GriddlesManual.pdf

Edit: I also noticed this


> Since the griddle is not fused, you must connect it to a fused circuit equipped with a
> suitable disconnecting means as required by local authorities.


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## icefalkon (Dec 16, 2007)

Dennis Alwon said:


> Notice also that the loads per phase on the 240V unit is lower than the 208 unit????? Also notice that the load per phase is no where near 80 amps. There are no 3 phase elements but rather single phase elements sharing 3 phases so the calc is not as simple. In fact you are way over and a 90 amp breaker is way high.


Yes, but the reason it was way high is because prior to posting the manual, no one knew that the load was broken into two parts. I just looked at the manual again and look what you come up with if you combine the amperage ratings of the two parts...

Waalaa...look at the X or A phase...with 208V it's 90A, and with with 240V it's 78A...

I'm glad I found and posted the manual for you Cletis! 

Good luck!

Steve from NYC


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## icefalkon (Dec 16, 2007)

hardworkingstiff said:


> I saw this note in the owners manual. Looks like you are supposed to supply 2 circuits.
> 
> 
> http://www.wolfstoves.com/pdf/site/WEG-GriddlesManual.pdf
> ...


Good catch! The manual is posted on p2 of this thread.

Steve from NYC


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## Cletis (Aug 20, 2010)

icefalkon said:


> Good catch! The manual is posted on p2 of this thread.
> 
> Steve from NYC


Yeah. Im firing my tech tomorrow as he gave me all this bogus info. Ill snap pics and get to bottom of this tomorrow.


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## hardworkingstiff (Jan 22, 2007)

icefalkon said:


> Good catch!


Thanks.


> The manual is posted on p2 of this thread.
> 
> Steve from NYC


Yes, but I couldn't read it too well. I had to find it to be able to see it better (that's why I posted the link too).


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## Cletis (Aug 20, 2010)

*Interesting*

Now, if this is fact. Which is weird. He told me there is only one connection on back with #6 stranded wire. I bet there were two sets and he didn't mention that.  Fired!! Anyhow, if we go by the 16kw and 10kw if we do a general calc @ 208 we would get 44 amps and 27 amps so if we multiply by 1.25 then I would need the conductors to be # 6 and #10 per 310.16 so a 60 amp and a 30 amp breaker would suffice normally BUT, by the chart phase a on the 30 amp total load takes 45amps on phase a then 27 amps on other two phases so basically I'm gonna need 2 - 60 amp 3 pole shunt trip breakers for this bad boy right ? Have any of you ever seen a double fed commercial appliance????


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## Dennis Alwon (May 9, 2009)

Cletis said:


> Then how would you calculate phase conductors? By nameplate 27kw or manual ??


The nameplate is only giving you the total connected load. Now that I can read the manual I would use that and I would run 2- 50 amp 3 phase circuits for 208V. The fact that the unit is 240V would change things a bit.

I still don't see how the load is greater for the 208V unit with the same kw rating


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## MikePEC (Jun 23, 2012)

Yes. Dish machine I will be wiring in a hotel kitchen requires two 3 phase 480 volt feeds one 50amp and 40amp.


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## Cletis (Aug 20, 2010)

Dennis Alwon said:


> The nameplate is only giving you the total connected load. Now that I can read the manual I would use that and I would run 2- 50 amp 3 phase circuits for 208V. The fact that the unit is 240V would change things a bit.
> 
> I still don't see how the load is greater for the 208V unit with the same kw rating


well, the phase a drew 45 amps then wouldn't you multiply that phase by 1.25 giving you 56.25 therefore a 60 amp breaker basically because of phase A ???



MikePEC said:


> Yes. Dish machine I will be wiring in a hotel kitchen requires two 3 phase 480 volt feeds one 50amp and 40amp.


I guess it's the wave of the future with these super high powered devices. I just havent seen any yet other than these new hot tubs on a 30 and 20


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## MikePEC (Jun 23, 2012)

The plumber that got me involved with this client that sells the equipment gave me the best advise ever, call the manufacture and talk with a tech so you know exactly what your up against!


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## hardworkingstiff (Jan 22, 2007)

Cletis said:


> Now, if this is fact. Which is weird. He told me there is only one connection on back with #6 stranded wire. I bet there were two sets and he didn't mention that.


I'll bet whoever wired it originally just went by the name plate rating and never read the instructions. Be careful about jumping your employee before you know what's going on.


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## icefalkon (Dec 16, 2007)

What's weird is the breakdown of phases on the smaller circuit...look at the difference 45A...then B and C are half of that! Why is that?


Steve from NYC


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## Cletis (Aug 20, 2010)

*dont*

That is odd. I have never ever seen such unbalanced load on 1 device before. But, I don't get around much like the super commercial guys. They can probably chime in on this. I bet the last guy just ran a 90 amp 3 pole and tied the two sets on with 90, which would probably work fine other than the #6's are fused wrong. Reminds me of a chandelier with 12 - #18 fixture wires all going to a 12-2 on a 20 amp breakers sort of


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## hardworkingstiff (Jan 22, 2007)

icefalkon said:


> What's weird is the breakdown of phases on the smaller circuit...look at the difference 45A...then B and C are half of that! Why is that?
> 
> 
> Steve from NYC


I agree. Looking at the manual, I'd say the 60" model will have a total of 10 elements. 6 are wired to the 1st set getting the 45 amps for all three phases. That would leave 4 elements to be wired up and you would get 1 leg lower than the other 2. If there were 5 elements, then I can see getting 1 leg lower than the other 2. Anyway, the amperage they state doesn't make sense.


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## icefalkon (Dec 16, 2007)

hardworkingstiff said:


> I agree. Looking at the manual, I'd say the 60" model will have a total of 10 elements. 6 are wired to the 1st set getting the 45 amps for all three phases. That would leave 4 elements to be wired up and you would get 1 leg lower than the other 2. If there were 5 elements, then I can see getting 1 leg lower than the other 2. Anyway, the amperage they state doesn't make sense.


Yeah, that's what I mean...it doesn't make sense. Whew...I thought it was just me there! LOL.

Now...I wonder if an intrepid guy could rewire them to make it more efficient?

Steve from NYC


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## Cletis (Aug 20, 2010)

*?*



hardworkingstiff said:


> I agree. Looking at the manual, I'd say the 60" model will have a total of 10 elements. 6 are wired to the 1st set getting the 45 amps for all three phases. That would leave 4 elements to be wired up and you would get 1 leg lower than the other 2. If there were 5 elements, then I can see getting 1 leg lower than the other 2. Anyway, the amperage they state doesn't make sense.


WHAT!!!!!!!!!!!!!!! A manual with incorrect information...well ...I .....never


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## 360max (Jun 10, 2011)

Cletis said:


> I think I"m down to Q = cm(delta)T now
> 
> Q = Heat added
> 
> ...


:laughing::laughing::laughing::whistling2:


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## 360max (Jun 10, 2011)

Cletis , I'm starting to think your Miller in disguise:shifty:


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## hardworkingstiff (Jan 22, 2007)

Dennis Alwon said:


> The nameplate is only giving you the total connected load. Now that I can read the manual I would use that and I would run 2- 50 amp 3 phase circuits for 208V. The fact that the unit is 240V would change things a bit.


Yea, instead of the load being 39A at 240 (since it's a resistance load) I calculate 33.8A at 208. I think 2 40-amp circuits work fine (assuming the equipment is not updated).


> I still don't see how the load is greater for the 208V unit with the same kw rating


They use elements with lower resistance on the 208 models which causes the amperage to go up so they can maintain the same KW ratings on the equipment.


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## Cletis (Aug 20, 2010)

*nope*



360max said:


> Cletis , I'm starting to think your Miller in disguise:shifty:


no way. That dude is psycho. EVer been over to his site? It's even too weird for me


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## BBQ (Nov 16, 2010)

Dennis Alwon said:


> I still don't see how the load is greater for the 208V unit with the same kw rating


yeah you do, you are just having a brain fart.


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## Cletis (Aug 20, 2010)

*?*



hardworkingstiff said:


> Yea, instead of the load being 39A at 240 (since it's a resistance load) I calculate 33.8A at 208. I think 2 40-amp circuits work fine (assuming the equipment is not updated).
> 
> The use elements with lower resistance on the 208 models which causes the amperage to go up so they can maintain the same KW ratings on the equipment.


that doesn't seem right. Can you recheck. i'm going with manual until proven otherwise...I'm assuming manual did not calculate in the 1.25 or did they?


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## hardworkingstiff (Jan 22, 2007)

Cletis said:


> that doesn't seem right. Can you recheck. i'm going with manual until proven otherwise...


You have a machine rated for 240-volts and pulls 39-amps @ 240-volts. It's a resistive load so E=IR straight up. Change your voltage (while the resistance stays the same) and the amperage changes the same % your voltage does. 

208/240=.8667, therefore 39*.8667=33.8 amps at 208V.



> I'm assuming manual did not calculate in the 1.25 or did they?


No, they did not, and it's not a continuous load so you don't need to. But, if you insist, 33.8*1.25=42.25


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## Cletis (Aug 20, 2010)

*45*



hardworkingstiff said:


> You have a machine rated for 240-volts and pulls 39-amps @ 240-volts. It's a resistive load so E=IR straight up. Change your voltage (while the resistance stays the same) and the amperage changes the same % your voltage does.
> 
> 208/240=.8667, therefore 39*.8667=33.8 amps at 208V.
> 
> ...


the manual said 45 not 49 and if they did not then 45 x 1.25 = 56.25 therefore 60 ????? Where did the 39 come from?


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## hardworkingstiff (Jan 22, 2007)

Cletis said:


> the manual said 45 not 49 and if they did not then 45 x 1.25 = 56.25 therefore 60 ????? Where did the 39 come from?


Check the manual again under the 240-volt rating and you will see the 39 amps.

Your pic says you have a 240-volt piece of equipment, not a 208-volt piece of equipment.


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## A Little Short (Nov 11, 2010)

The reason for the two circuits is actually a code requirement. Anything with surface heating elements with more than 60A demand shall have its power supply subdivided into two or more circuits, each of which with a 50A max OCPD.

422.11(B)


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## hardworkingstiff (Jan 22, 2007)

Little-Lectric said:


> The reason for the two circuits is actually a code requirement. Anything with surface heating elements with more than 60A demand shall have its power supply subdivided into two or more circuits, each of which with a 50A max OCPD.
> 
> 422.11(B)


I knew I remembered reading that but just had no idea where it was.


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## hardworkingstiff (Jan 22, 2007)

*Something else to tell your customer*

Power = volts x amp x PF (which is 1 in this case)

Power (@240V) = 240*39= 9.36kW
Power (@208V) = 208*33.8 = 7.03kW

7.03/9.36 = 75%

The equipment will only work to 75% of it's rating wired to 208V.


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## Cletis (Aug 20, 2010)

*75%*



hardworkingstiff said:


> Power = volts x amp x PF (which is 1 in this case)
> 
> Power (@240V) = 240*39= 9.36kW
> Power (@208V) = 208*33.8 = 7.03kW
> ...


You think that can translate to 75% of 450F ?? 337F ?? or not ? that would suck


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## Dennis Alwon (May 9, 2009)

Cletis said:


> You think that can translate to 75% of 450F ?? 337F ?? or not ? that would suck


I doubt that can translate quite that simply but it will definitely take longer to get hot.


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## icefalkon (Dec 16, 2007)

Cletis said:


> You think that can translate to 75% of 450F ?? 337F ?? or not ? that would suck


LOL the eggs will take longer to cook now...but the bacon should be justtttt fine! LOL


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## hardworkingstiff (Jan 22, 2007)

Cletis said:


> You think that can translate to 75% of 450F ?? 337F ?? or not ? that would suck


I never looked at it that way. I would think it will take 33% longer to do the same work (1 unit at 240 / .75 rating at 208 = 1.33 units or 33% more).

It would be interesting if it could only heat up to 75% of the max temperature.


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## BBQ (Nov 16, 2010)

hardworkingstiff said:


> The equipment will only work to 75% of it's rating wired to 208V.


I think it would be more accurate to say the heating elements will only reach 75% of their rating. The surface temp of the griddle will still likely be 100%, just slower to get there.


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## Cletis (Aug 20, 2010)

*thread*

I will be calling vulcan tech support tomorrow and just do what they recommend. I'll report back. I think that this is one of my more productive threads on here. I learned a new code ref today about the 2 loads. The fun and excitement never ends with NFPA 72


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## icefalkon (Dec 16, 2007)

I agree with BBQ, I think that the surface will indeed reach max temperature, it'll just take longer to get to that point...being that the griddle will be on for most of the day or morning at least...that shouldn't be a problem.


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## BBQ (Nov 16, 2010)

icefalkon said:


> I agree with BBQ, I think that the surface will indeed reach max temperature, it'll just take longer to get to that point...being that the griddle will be on for most of the day or morning at least...that shouldn't be a problem.


The only way I can see a problem is if the place is really high volume and puts so much cold meat on it so often that it the reduced output of the elements can't keep up. 

Of course I think we can all agree getting the right voltage would be better.

A simple solution would be buck boost transformers considering the equipment has already been selected.


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## icefalkon (Dec 16, 2007)

BBQ said:


> The only way I can see a problem is if the place is really high volume and puts so much cold meat on it so often that it the reduced output of the elements can't keep up.
> 
> Of course I think we can all agree getting the right voltage would be better.
> 
> A simple solution would be buck boost transformers considering the equipment has already been selected.


I totally agree with you on that...the cold meat will continually bring the temp down.

But using the BB tranny will cost money...and from what it seems...the guy is in short supply. Adding that much to the installation IS justified though to do it the right way.That would be a justified extra to the owner to make the grill operate at full efficiency.


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## hardworkingstiff (Jan 22, 2007)

One thing I've never been sure of is the relationship between voltage and a heating element and the amount of heat generated.

In other words, if you have a 240-volt rated element, and you have it heated and full load, what happens if you were to reduce the voltage by 10%? Does the heat produced drop by 10% or does it drop more than 10%?

Let's ask this a different way. Using this same element, if I had 100-volts on it and increased the voltage by 10-volts, would I get the same temperature increase if I started with 230-volts and raised 10-volts?


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## Cletis (Aug 20, 2010)

*...*



hardworkingstiff said:


> One thing I've never been sure of is the relationship between voltage and a heating element and the amount of heat generated.
> 
> In other words, if you have a 240-volt rated element, and you have it heated and full load, what happens if you were to reduce the voltage by 10%? Does the heat produced drop by 10% or does it drop more than 10%?
> 
> Let's ask this a different way. Using this same element, if I had 100-volts on it and increased the voltage by 10-volts, would I get the same temperature increase if I started with 230-volts and raised 10-volts?


I don't think it's a linear relationship. More of a logrythmic curve


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## hardworkingstiff (Jan 22, 2007)

Cletis said:


> I don't think it's a linear relationship. More of a logrythmic curve


Anyone have a graph of this curve?


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## hardworkingstiff (Jan 22, 2007)

Cletis said:


> I don't think it's a linear relationship. More of a logrythmic curve


Depending on the slope of the curve, you may have an even greater (or less) difference in performance that we have discussed. I hope you get some good info from Vulcan tomorrow (don't forget about us).


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## Cletis (Aug 20, 2010)

*BJ*



hardworkingstiff said:


> Anyone have a graph of this curve?


Brian John should. He has graphs, charts, historical time tripping charts, pie charts, scales, IR photos, fault current trip charts, you name it


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## Cletis (Aug 20, 2010)

*Update*

Update:

Just talked with tech. It is a variable adjustable resistance griddle. So, basically it will draw the 45 amps (already figured in 1.25) for each circuit. therefore, I just need to run 2 circuits # 8 Cu (i'll probably run #6 though) on 3 pole 50 amp ocpd shunt trip breakers. He said it will adjust to lower voltage and give the same heat output and will heat up just about as quick. 

BAM!!!


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## hardworkingstiff (Jan 22, 2007)

Cletis said:


> He said it will adjust to lower voltage and give the same heat output and will heat up just about as quick.


I wonder what his education level is. Intuitively it does not sound correct.

Thanks for the update.


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## icefalkon (Dec 16, 2007)

Cletis said:


> Update:
> 
> Just talked with tech. It is a variable adjustable resistance griddle. So, basically it will draw the 45 amps (already figured in 1.25) for each circuit. therefore, I just need to run 2 circuits # 8 Cu (i'll probably run #6 though) on 3 pole 50 amp ocpd shunt trip breakers. He said it will adjust to lower voltage and give the same heat output and will heat up just about as quick.
> 
> BAM!!!


Wow. Ok cool. Good for you Cletis. It became a no brainer installation now lol


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## BBQ (Nov 16, 2010)

hardworkingstiff said:


> I wonder what his education level is. Intuitively it does not sound correct.
> 
> Thanks for the update.


Same amps less voltage you know as well as i do it can't heat as quick


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## hardworkingstiff (Jan 22, 2007)

BBQ said:


> Same amps less voltage you know as well as i do it can't heat as quick



Yea, kind of why I asked about his education level. :laughing:

I just love to stir the pot.


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## Cletis (Aug 20, 2010)

*update*

Here is update. We fired up the griddle. EVerything appeared ok. We went out to truck and when came back in cook said there was a big pop and light coming out the back. The breaker was tripped. We opened up our ends. No sign of a short or nick or anything really. We clamped on a meter and fired back up and everything went perfect. 35 amps per phase except third phase was around 20 at max settings. Ran for an hour with no problems. Cooked some eggs at end to test before we left. Any ideas of the appearent dead short that happened? Sounds like an element shorted but either cleared itself out or lost an element???


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## Cletis (Aug 20, 2010)

Cletis said:


> Here is update. We fired up the griddle. EVerything appeared ok. We went out to truck and when came back in cook said there was a big pop and light coming out the back. The breaker was tripped. We opened up our ends. No sign of a short or nick or anything really. We clamped on a meter and fired back up and everything went perfect. 35 amps per phase except third phase was around 20 at max settings. Ran for an hour with no problems. Cooked some eggs at end to test before we left. Any ideas of the appearent dead short that happened? Sounds like an element shorted but either cleared itself out or lost an element???


Pics


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## Awg-Dawg (Jan 23, 2007)

Cletis said:


> Pics


 

Ground wire is marked with tape.:no:


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## drspec (Sep 29, 2012)

Friction tape? Could be a nick in your phase taping of those in line lugs. In a case like that, polaris lugs are the way to go.


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## Cletis (Aug 20, 2010)

*law*



Awg-Dawg said:


> Ground wire is marked with tape.:no:


Yeah. Good eye. I definately broke the law there for sure. Marking #8Thhn green is definately a major code infraction yet marking #6 is ok for some reason? Any ideas why the change from 6 to 8? I actually just didn't want to buy a whole roll (500ft) of #8 green for only a 27ft run. lol 



drspec said:


> Friction tape? Could be a nick in your phase taping of those in line lugs. In a case like that, polaris lugs are the way to go.


Chances of that are slim but still possible. We use 33+ and wrap heavily. We opened it all up and no signs of short at all. Also, it ran 7-15 min before it blew anyhow? The device was sitting totally stationary. If there was ashort, it would of happened right away I would think. Which makes me think it was something internal like another element kicking in or something. Anyhow, it cleared itself out and I havent got a call yet in last 3 hrs it been on. I would just like to know what happened.


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## Awg-Dawg (Jan 23, 2007)

Cletis said:


> Any ideas why the change from 6 to 8?


 
Its actually #4 and larger.

I dont know the reason why it starts there.


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## Cletis (Aug 20, 2010)

*?*



Awg-Dawg said:


> Its actually #4 and larger.
> 
> I dont know the reason why it starts there.


I'm curious to the reason. For some reason I thought it was 6. Is is cause the tape will wrap around better because of larger diameter and not bunch up like on a #12 or is it some other reason ??


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## hardworkingstiff (Jan 22, 2007)

I guess you don't have before/after amperage readings to compare?


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## Awg-Dawg (Jan 23, 2007)

Cletis said:


> For some reason I thought it was 6.


 
Im too lazy to look, but the wording is something like "for conductors larger than 6" you can reidentify.

I imagine that is why .


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## hardworkingstiff (Jan 22, 2007)

If those white cables are the factory cables, aren't you missing one (according to the wiring label?


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## Cletis (Aug 20, 2010)

hardworkingstiff said:


> If those white cables are the factory cables, aren't you missing one (according to the wiring label?


****!!!!!


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## Cletis (Aug 20, 2010)

Cletis said:


> ****!!!!!


Here are the 2 ports


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