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Kevin
Kevin, Licensed Electrical Contractor
Category: Electrical
Satisfied Customers: 3663
Experience:  30 years Licensed Electrical Contractor in Illinois, Adjunct College Electrical Instructor, Former Electrical Inspector, Diploma: Digital Electronics, FCC Technician License
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I am review a electrical plan. The plans show a generac QT080

Customer Question

I am review a electrical plan. The plans show a generac QT080 single phase 120/240 with a 400a over current protection. The question, Why does it have a 400a OCP protecting a 80k? 80,000 divide by 240 equals to 333a. According to the National electrical code ART 240.6 the next standard size OCP is 350A. How is Generac calculating this. Please show me. I am a electrical plans reviewer.
Submitted: 2 years ago.
Category: Electrical
Expert:  Kevin replied 2 years ago.
Hello.....my name is ***** ***** I will be happy to assist you with your electrical question. My goal is to exceed your expectations on Just Answer!
1) Are you referring to the internal (built-in) 400 amp breaker provided by Generac or a 400 amp OCPD in another panelboard that is not part of the generator?
Customer: replied 2 years ago.
A built in 400A OCP. Factory installed.
Expert:  Kevin replied 2 years ago.
Thank you for the replies. 1) Yes, you are correct in your math by applying Watts Law. 2) Since the OCPD in question is part of a manufactured electrical component and is not part of premise based wiring, Article 240.6 is not applicable in my opinion. The ratings shown in Article 240.6 are only applicable for premise based overcurrent protection. 3) It is my interpretation that Article 90.7 (Examination of Equipment for Safety) supercedes Article 240.6 and takes precedence. 4) Since the generator is has been "UL" tested and "Listed", the 400 amp OCPD that is integral to the Generac as part of a manufactured electrical assembly and is not mandated by the NEC and does not need to comply with the requirements of Article 240.6. Consumer products such as a generator are tested, certified and listed by a 3rd party testing lab such as "UL" in this product and not mandated by the NEC. 5) Shown below is an excerpt from Article 90.7 "It is the intent of this Code that factory-installed internal wiring or the construction of equipment need not be inspected at the time of installation of the equipment, except to detect alterations or damage, if the equipment has been listed by a qualified electrical testing laboratory that is recognized as having the facilities described above and that requires suitability for installation in accordance with this Code". Hope this helps………If you have any additional questions, let me know and I’ll be glad to answer them for you. Otherwise, don’t forget to rate me before you log Off. The next time you have an electrical question, you can also request for me at: http://www.justanswer.com/home-improvement/expert-your-electrician ……….Thanks…………..Kevin!
Expert:  Kevin replied 2 years ago.
If you have any additional questions, let me know and I’ll be glad to answer them for you. Otherwise,don’t forget to rate me before you log Off.