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Mark Henley
Mark Henley, Journeyman Technician
Category: HVAC
Satisfied Customers: 3217
Experience:  UA Journeyman Pipefitter , HVAC, Refrigeration, DDC controls. 26 years.Commercial & residential
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I have a question that was on a Ky journeyman HVAC Mechanic

Customer Question

I have a question that was on a Ky journeyman HVAC Mechanic test i took.
how do you figure the heat load of a 20 amp breaker? I know several union electricians and a lineman for Duke energy and all 4 of them were clueless as i was. I've never heard of such a thing. I've always used a 12 Guage wire and made sure my load didnt exceed 20 amps.

i think the answers given were 10, 12, 16 and 20. i chose 20 and it was wrong.
Submitted: 7 years ago.
Category: HVAC
Expert:  Kenton Guidry replied 7 years ago.
This website has a wonderful explanation.

http://howto.altestore.com/How-to-Size-Wiring-and-Cabling-for-Your-System/a62/

VDI = (AMPS x FEET)/(%VOLT DROP x VOLTAGE)
Customer: replied 7 years ago.

that site really doesnt help.

 

the way the test question was worded from Pearson Vue, the test giver, simply ask what is the heat load of a 20 amp breaker. It did not give wire size, volts, amps, load, length of run, ect... like you would see in a real world situation. just simply the question, with 10, 12, 16 or 20 as answers.

Expert:  Mark Henley replied 7 years ago.
Hi,

Answer was 16 , 80% is the rating for heat load.

Thanks

Mark
Mark Henley, Journeyman Technician
Category: HVAC
Satisfied Customers: 3217
Experience: UA Journeyman Pipefitter , HVAC, Refrigeration, DDC controls. 26 years.Commercial & residential
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