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Kevin, Licensed Electrician
Category: Electrical
Satisfied Customers: 2835
Experience:  29 years as a Licensed Electrical Contractor in Illinois, 5 year college Electrical Instructor, Former Electrical Inspector, Diploma in Digital Electronics, Former Illinois Licensed Home Inspector
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Why does a emergency backup auto Generac installation, I've

Customer Question

Why does a emergency backup auto Generac installation, I've seen, not have a (main)emergency shut down circuit breaker on the separate circuit breaker panel (downstream) that was installed for the Generac system? One that would disconnect all power sources from home? Basic safety for first responders? Is this not a N.E.C. requirement?
Concern: In emergency condition, turning off the 'Main' original circuit breaker panel, Would cause emergency backup auto Generac system to provide back up power to this home. (my opinion)
Common sense suggest complete power provided to home should also be controlled by a easily accessible (identified) circuit breaker, in basement. This could/should be easily mounted on the circuit breaker (additional) basement panel installed for Generac system.
I was shown by a Wolverine service tech, the control breaker located inside the locked Generic unit/cabinet, located outside the home. Also shown the shut off propane control valve for the Generic power source unit.
In a emergency situation, finding a key, unlocking the box outside the home, or shutting off propane fuel source may be too late.
Submitted: 27 days ago.
Category: Electrical
Expert:  Kevin replied 27 days ago.

Hello and welcome to Just Answer. My name is ***** ***** I will be happy to assist you with your electrical question.

1) Article 702.5 (Transfer Equipment) within the National Electrical Code requires that all standby or portable generator installations have either a manual or automatic transfer switch installed or an Interlock device (commonly used for portable generators) installed on the main breaker of the electrical panelboard to prevent back-feeding standby power to the public utility grid during a power outage.

Back-feeding alternate power to the public utility grid either by generator or solar or wind or inverter when not having the proper transfer equipment installed at the main service is a direct violation of the NEC.

2) An automatic transfer switch is just that. The ATS automatically transfers the interconnection of utility grid and alternate sources of supply voltage via a contactor. Older versions of ATS's did not have a main service disconnect as you mention. Generac also sells a Load Center transfer switch which is installed like a sub-panel and contains the critical circuit breakers that can manually be turned OFF. Generac sells an optional GenReady Load Center that provides for manual or automatic operation. In addition, Generac also sells an open transition ATS version.

See Generac link shown below for automatic transfer switches:

3) A Liquid Propane (LP) tank should always contain a manual disconnect shut OFF valve at the tank in addition to the shut off valve at the generator.

4) Last but not least, keep in mind that the local Authority Having Jurisdiction (local electrical inspector) can always over ride the NEC as local electrical codes can take precedence. The AHJ has the final say-so as to the type of transfer switches allowed within their local code jurisdiction.

If you have any additional questions, just let me know and I’ll be glad to answer them for you.

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