help load calculations

[gunter78911]

help i failed a test in load calculations, branch and feeder Circuits.
I dont really have anyone to help me, and i'm trying to figure this out on my own.
I'm about ready to drop my apprentice ship program, and try to be an union apprentice.
I think i'll get better schooling.

What's is the required circuit ampacity for a noncontinuous, three-phase load of 8kW at 208V ?

I just need to stay curent with my apprenticeship, till there accepting applacations at the union.

 

[Dennis Alwon]

Amps = watts/voltage. For voltage 3 phase use 208 times the sq. root of 3 or 1.73

 

[Hv&Lv]

http://ecmweb.com/mag/electric_understanding_basics_wye/

Here is an article with lots of good information...

 

[gunter78911]

Thank you guy's so much.

So....8000W/ (208*1.732) or 8000W/360.256 = 22.064 amps ?

 

[pete m.]

Thank you guy's so much.

So....8000W/ (208*1.732) or 8000W/360.256 = 22.064 amps ?

Thats what my calculator reads. :happyyes:

Pete

 

[charlie b]

Keep in mind that the question specifically said the load was not continuous. If they instead told you that the load was continuous, you would have to multiply the required ampacity by 1.25 (i.e., add an extra 25%). That would have made your answer 27.58, instead of 22.06.

 

[texie]

help i failed a test in load calculations, branch and feeder Circuits.
I dont really have anyone to help me, and i'm trying to figure this out on my own.
I'm about ready to drop my apprentice ship program, and try to be an union apprentice.
I think i'll get better schooling.

What's is the required circuit ampacity for a noncontinuous, three-phase load of 8kW at 208V ?

I just need to stay curent with my apprenticeship, till there accepting applacations at the union.

Don't give up, hang in there! You'll get it in time. It's all about the drive. I'll admit the union has some good programs but there are some good non union programs out there.

 

[gunter78911]

Thanks everyone!

these questions are out of my work book, but i have to take retest on this chaper.

 

[T.M.Haja Sahib]

Thank you guy's so much.

So....8000W/ (208*1.732) or 8000W/360.256 = 22.064 amps ?

There is one difficulty here.The nature of load was not stated by you.If it is purely resistive,the answer is correct.Otherwise the power factor of the load should be multipied into the denominator to arrive at the current.The resulting current will always be higher.