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Kevin
Kevin, Licensed Electrician
Category: Electrical
Satisfied Customers: 914
Experience:  27 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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I have a 6,000 watt generator and have installed an outside

Resolved Question:

I have a 6,000 watt generator and have installed an outside 30 amp connect block to a transfer switch connected to my main panel box. The main panel feeds a 30 amp sub-panel with #8 stranded wire which in turn feeds my kitchen.

The transfer switch uses 20 amp #12 stranded wire to feed the breakers. I need to enable electricity to my kitchen (microwave and refrig) via the transfer switch. My concern is that I may over tax the # XXXXX wires from the transfer switch that feed the 50 amp, 240v breaker going to the sub panel.

The solution seems to be to add a 240v, single circuit 30 amp transfer switch to the sub panel directly from the outside generator feed and then to continue the line to feed the main transfer switch exclusive of the 240v sub panel breaker.

Is this electrically kosher or am I smoking something?
Submitted: 7 months ago.
Category: Electrical
Expert:  Kevin replied 7 months ago.

Hello Kevin........my name is XXXXX XXXXX and I will be happy to assist you with your electrical question. My goal is to exceed your expectations on Just Answer!

 

1) Can you expand on your question? Is your intent to have (2) two separate transfer switches?, ie...., (1) one Xfer switch at the main panel and a secondary Xfer switch at the sub-panel? Based on your initial question, I am unable to follow what you would like to accomplish? Can you clarify?

 

2) Is the Xfer switch an automatic Xfer switch or a manual Xfer switch or a manual "Inter-Lock" device @ the main panel using a 30 amp double pole breaker to back-feed from the gen set?

 

3) You mention a 30A sub-panel and a 50 amp breaker. What is the size of the feeder breaker located in the main electrical panel that feeds the sub-panel? 30 or 50 amps? Is the sub-panel a main lug or main breaker? If a main breaker sub, what is the breaker size?

 

 

 

Customer: replied 7 months ago.

Thanks for your response. I will try to clarify and answer your questions in order asked.


 


1. My overall concern is the use of #12 wire from the 6 circuit transfer switch to feed a 240v, 30 amp sub panel. My 'intent' is to have 2 transfer switches fed directly from the outside connect block from my generator. The first in line would be a 30 amp, single circuit transfer switch that feeds my sub panel. The second, fed also from the outside input line, would continue to a 6 circuit transfer switch that controls various circuits in my house.


 


2. Each transfer switch is manual, not an inter-lock or back fed.


 


3. The sub panel is 30 amp and does not have a main breaker. I think that it is called a mail lug.


 


I hope that this clarifies. I apologize for the confusion.

Customer: replied 7 months ago.

I replied to your questions but no response yet. Is that the end of the conversation?

Expert:  Kevin replied 7 months ago.

Kevin...........thank you for the reply and clarification.

 

1) Is the gen-set a portable or a standby?

 

2) Since the gen-set is a 6KW, I assume that you are only looking to back-up power to critical circuits in the house, possibly the fridge, well, furnace, a sump pump (if applicable), lighting circuit?

 

3) 12 AWG stranded copper is only rated at 20 amps and not 30 amps. For a 30 amp rating, the feeder conductors need to be sized as a minimum of 10 AWG Stranded copper or possibly 8 AWG if the distance is exceeded due to any voltage drop from the conductors. If the main panel has a double pole 30 amp feeder breaker and those conductors are feeding into a 30 amp main lug panel, the conductors need to be minimally sized as 10 AWG Stranded copper.

 

4) In a generator installation ,there is no need for having multiple Xfer switches and I would not recommend such an installation. A gen-set Xfer is only installed at the main service panel and NOT co-located both at the main and at a sub-panel running dual Xfer switches. The intent of an Xfer switch is to prevent back-feed power to the utility grid from the main service panel. The main service entrance, ie... main panel is the location where the gen-set power needs to stop the current flow out to the grid.

 

5) Many Multi-story commercial buildings and factories all have numerous sub-panels installed throughout the various floors or areas of a building using (1) one generator, yet they only have (1) one Xfer switch located at the main switchgear or main panel. They do not have multiple Xfer switches installed. A single family dwelling is no different... just on a smaller scale.

 

Hope this helps............If you have any other questions, just let me know.

 

If no other questions, don't forget to rate me before you log off..............Thanks..........Kevin!

 

 

Kevin, Licensed Electrician
Category: Electrical
Satisfied Customers: 914
Experience: 27 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
Kevin and other Electrical Specialists are ready to help you
Customer: replied 7 months ago.

Since my sub panel is 20 feet away from my main panel and transfer switch, it appears that I will have to extend the transfer switch wiring to feed specific breakers for my microwave and fridge in the sub panel using #12 wire and leave the 30 amp breaker in the main panel alone as is.



Thank you for your help. It was tremendous and I'm going to try to tip you.


 


 

Expert:  Kevin replied 7 months ago.

1) Yes, just extend the Xfer conductors to feed those specific breakers that you need to provide back-up power to.

Kevin, Licensed Electrician
Category: Electrical
Satisfied Customers: 914
Experience: 27 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
Kevin and other Electrical Specialists are ready to help you
Expert:  Kevin replied 7 months ago.

Kevin..........Thank you very much for the excellent service rating as well as the generous bonus.......both are much appreciated!

 

If you have any other questions, just let me know.

 

Take care and have a great weekend..............Thanks............Kevin!

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