Load

[Kevin.hndz]

Can someone teach me how to calculate what size wire for the commercial mixer ?

New item by Kevin Hernandez

photos.app.goo.gl

 

[LarryFine]

It's labeled 100a, so you need a conductor suitable for 125a if continuous, or for 100a if it's not.

 

[infinity]

What voltage are you using?

 

[Kevin.hndz]

What voltage are you using?

208

 

[infinity]

208

What kind of load is this just motor(s)? If so your current will be higher than the nameplate at 208 volts.

 

[Tulsa Electrician]

Pic of name plate.

 

[Kevin.hndz]

It's labeled 100a, so you need a conductor suitable for 125a if continuous, or for 100a if it's not.

Number 3 ?

 

[LarryFine]

Number 3 ?

Yes, #3 cu is rated for 100a.

 

[infinity]

Number 3 ?

You still didn't say what kind of load it is? You said a mixer so if it's a 220 volt rated motor load at 208 volts it will draw more than 100 amps.

 

[Teaser2]

Just make sure that this not a 3 phase mixer: 3X220V +PE. 3 phase 220V with a ground. (As you know, in Europe 220/380V, however, it is still a possibility)

 

[Knightryder12]

Its labeled as 26kw at 220V, 3 phase. 26kw is only 68.2 amps. At 125% that's only 85.29 amps. Wondering where the 100 amps is coming from. Found another one of these machines on the web and it was a 208V model and it was listed at 25kw and 100 amps???

 

[Jraef]

Just make sure that this not a 3 phase mixer: 3X220V +PE. 3 phase 220V with a ground. (As you know, in Europe 220/380V, however, it is still a possibility)

It's labeled for 60Hz, so it would not be showing that if intended to be used in Europe. It was likely purposely built for export to North America, so they got a 220V 60Hz rated motor for it.

My concern would be that motor's tolerance for accepting 208V 60Hz. 220V has not been an industry standard for motor designs for more than 50 years, so it's likely they have taken a 50Hz motor and re-rated it for 60Hz already, so running it at 95% voltage SEEMS like it would be OK, but we don't know how they got that 220V rating, especially if that "2013" is the manufacturing date (which is likely given that they have a web address on the label).

 

[Teaser2]

It's labeled for 60Hz, so it would not be showing that if intended to be used in Europe. It was likely purposely built for export to North America, so they got a 220V 60Hz rated motor for it.

My concern would be that motor's tolerance for accepting 208V 60Hz. 220V has not been an industry standard for motor designs for more than 50 years, so it's likely they have taken a 50Hz motor and re-rated it for 60Hz already, so running it at 95% voltage SEEMS like it would be OK, but we don't know how they got that 220V rating, especially if that "2013" is the manufacturing date (which is likely given that they have a web address on the label).

I understand. OP needs to gather more information with this mixer in order to know what to do for sure. Thank you for the feedback.

 

[Jpflex]

It's labeled 100a, so you need a conductor suitable for 125a if continuous, or for 100a if it's not.

Not all appliances are considered continuous loads. How would you recommend figuring this out on an appliance per appliance basis if you are not certain which should be continuous with a 125% factor included for ampacity?

Example nameplate doesn’t say continuous and manufacture manual isn’t present etc or are you just supposed to know all the sections in NEC that list certain appliances as continuous?

 

[infinity]

Not all appliances are considered continuous loads. How would you recommend figuring this out on an appliance per appliance basis if you are not certain which should be continuous with a 125% factor included for ampacity?

Example nameplate doesn’t say continuous and manufacture manual isn’t present etc or are you just supposed to know all the sections in NEC that list certain appliances as continuous?

Take a look at the Article 100 definition of continuous load. It should be very clear as to how it's applied.

 

[Jpflex]

Yes, #3 cu is rated for 100a.

What about termination temp rating, are we assuming 75 degrees or 60 degrees for a 100 ampere circuit?

Which brings another question: code requires 60 degree termination for wires between 14 to 1 AWG or 100 amperes or less

However if you size the 100 ampere wire and OCPD to 125 i amperes does the rule change to 75 degree termination because the circuit has changed over 100 amperes?

 

[Jpflex]

Take a look at the Article 100 definition of continuous load. It should be very clear as to how it's applied.

But it’s not clear and code contradicts itself. For example dwelling lighting load can draw maximum current ampacity rated for a circuit over 3 hours and not be considered continuous but if you do the same in an area for non dwelling all of a sudden it’s now considered continuous.

I have found books to state this but I haven’t seen the NEC book flat out state that dwelling lighting and general receptacle loads are not to be counted as continuous even if the circuit reaches maximum current for 3 hours or more. That is unless there is a small foot note or section I missed?

 

[Jpflex]

Yes, #3 cu is rated for 100a.

If terminations are marked for 60 degrees celcius I believe you would need a much larger size wire #1

But if termination on both sides of wire are rated at. 75 degrees celcius, you can go # 3 THHN

 

[infinity]

But it’s not clear and code contradicts itself. For example dwelling lighting load can draw maximum current ampacity rated for a circuit over 3 hours and not be considered continuous but if you do the same in an area for non dwelling all of a sudden it’s now considered continuous.

I have found books to state this but I haven’t seen the NEC book flat out state that dwelling lighting and general receptacle loads are not to be counted as continuous even if the circuit reaches maximum current for 3 hours or more. That is unless there is a small foot note or section I missed?

You're not missing anything. The definition is short and sweet, only 15 words. There are two components, time (3 hours or more) and load (maximum load on the circuit). In a dwelling if you had say 5 rooms of recessed lighting on a single circuit all 5 of those rooms would have to be on simultaneously for 3 or more hours for the load to be continuous. Even if all 5 rooms were on at the same time for 3 or more hours if any of those rooms had a dimmer and was not used at 100% output the load is not continuous.

Now if you have an office building where the all of the lights on a circuit all get turned on at 8:00 AM and off at 6:00 then that would be more than 3 hours at maximum load making it a continuous load. If the bathrooms lights are on that same circuit have an occupancy sensor then the load is no longer continuous.

 

[Knightryder12]

What about termination temp rating, are we assuming 75 degrees or 60 degrees for a 100 ampere circuit?

Which brings another question: code requires 60 degree termination for wires between 14 to 1 AWG or 100 amperes or less

However if you size the 100 ampere wire and OCPD to 125 i amperes does the rule change to 75 degree termination because the circuit has changed over 100 amperes?

That only applies if you are uncertain about the terminal ratings. Most everything made in the last 30 years or so should and would have 75 degree rated terminals.