Cord & Plug connected load, multiwire circuits

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marmorcam

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Hello!!

I am trying to size a panel for a Barber Shop and Beauty Salon. I do not know if the loads connected would be Cord & Plug (and have to reduce the ampere rating to 80%) or not. I mean, for example, can I have 3 hair dryers on a 30 A circuit, 208v? (that would be 208*30= 6240W (yes!!), but 208*30*0.8=4992W (no!!) ) and so on with all the other loads (they are basically all receptacles at 120v or 208v where you connect barber and beauty salon stuff!)

And I had another question: Is a 208v circuits (from a 120/208Y panel) a multiwire circuit? I do not understand quite well the NEC definition! I would say yes because it has two ungrounded conductors (then the 120v circuits would not be?)

I am a mess! But it is quite difficult to understand all the definitions in another language!!

Thank you very much for your help!
 
mwm1752 said:
you need a qualified professional to do the work --
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It is just a degree project...Just wanted a little bit of help, I am new in this whole electricity world...Do not think I am asking too much, I doubt that anyone of you was born knowing everything!
 
I am confused, You are in Spain. They have 120v receptacles? Thought all was 220 or something.


Your profile states you are a Engineer, what type may I ask. Electrical?
 
I think you are approaching the situation backwards. Start by finding out how much load each of the hair dryers (or other items) will draw. For example, if each hair dryer is to be served by 208 volts, single phase, and if each draws 8 amps (i.e., 8 x 208 = 1,664 watts), and if they are all plug and cord connected to a 30 amp branch circuit, then Table 210.21(B)(2) says your limit is 24 amps, and three hair dryers would fall just within that limit. But if each hair dryer requires more than 8 amps, then you cannot have three of them plugged into the same circuit.

As question about the 208 volt circuits, they may or may be "multi-wire branch circuits." If all you have is two ungrounded conductors, then the answer is no. If you also have a neutral conductor (i.e., it is a 120/208V, single phase circuit), then the answer is yes. But that is not the whole story. We are allowed to install MWBC under certain circumstances. One is if each of the ungrounded conductors is part of a line-to-neutral circuit. Another is if the circuit supplies only one utilization equipment. See 210.4 for more information.
 
I do believe they print a spanish version of the NEC -- I was not trying to offend but commercial building for public use gennerally have engineered documents. I have great respect for engineers knowledge of force,leverage & mathmatics when it comes to designing complicated systems, & structures.
 
Sierrasparky said:
I am confused, You are in Spain. They have 120v receptacles? Thought all was 220 or something.
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Sierrasparky said:

Your profile states you are a Engineer, what type may I ask. Electrical?
Click to expand...

No we do not, but I am trying to extrapolate my knowledge..!
And yes, I am an engineer, not electrical but energetic, building physics specialized!

Thank you very much to all of you, that actually helped!
 
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