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How to Prepare an Electrical Panel for a Generator


By Dave Rongey - Summary:

Identify the Condition of Electrical Circuits to Prepare for a Generator : When planning to install a generator it is best to survey the existing electrical system of the home to avoid any problems and have a safe and functional system when generator power is needed. As we see from this photo and the condition of the electrical circuits as described there are some areas of concern that will need to be addressed.


Before Installing a Home Generator

Electrical Question: Currently I have a Main 100W breaker panel for my house. Back in the day they pulled wires from everywhere and anywhere to get power to where they needed it.  So when I did some testing to see what breaker was for what I had a breaker running some things in the master bedroom along with some items in the kitchen and what have you. This is all over the house though, and from doing some small upgrades and installs myself I have come across 14 gauge and 12 gauge wiring on the same breaker and its a mess. BUT no breakers are tripping yet and no issues yet. All the breakers as you can see in pic are 20a but are all different and not uniform.

electrical panel wiring

Here is what I would like to do thought as my next project for the house. We do not get hurricanes so no outages from that, BUT we do get strong winds and earthquakes which will cause an outage at some future point. So instead of sitting in the dark I would like to create a back up system, And this was my thought process:

  • I would like to remove 6 or 8 of the current breakers in the main panel, the ones I consider essential that I will need during a power outage, the fridge, lights, TV, microwave, etc., and install them in a smaller sub panel that I will locate right next to the main panel. I will move the washer and dryer 40 amp double pole breaker that is in the top right slot down 4 spaces and and move the 4 single breakers to the sub panel. In place of the 40amp breaker I will install a new 60 amp double pole breaker that will power the sub panel.
  • I will then use 6 gauge wire to connect the 60a breaker to another 60a breaker I will install in the sub panel. In addition to the 60a double pole breaker and all the relocated breakers from the main I will install a 30a double pole breaker that will connect to a 4 prong 30a receptacle with 10 gauge wire that will be where I plug in a liquid propane 6kw generator that will thus power the sub panel and the breakers in it during the outage. For a fool proof measure I will install a interlock transfer switch kit so that we don’t have a back feed issue when main power comes back online.

Lastly, I have an email into this company to see if L.A. D.W.P. (Los Angeles Division of Water and Power I believe) approves of this device being installed on my meter, if it is and I can do that it would be cheaper and easier but I doubt L.A. D.W.P. will say yes. The Generlink device is being considered.

Well that was a long winded email and I apologize for that but I wanted to get you pics of what I have currently, what I am delaying with and what I hoped to accomplish. I am confident with the right guidance I can do almost anything (even though I am not an electrician) BUT with that said, if i get in over my head or this becomes unsafe or “not right ” for me to do.. then of course I will call in for a professional back up.

Questions about the Generator Connection to the Electric Panel
If I install that interlock transfer switch kit to my main breaker do I need to do the whole Sub Panel install? Or can I just do an instal of a weatherproof box with a 4 prong 30 amp receptacle for the generator to plug into and then a 30 amp in place of where I was going to put the 60 amp breaker (where the current 40 amp breaker is for the washer dryer)?

Thank you for your time and I truly appreciate any and all feedback.

This home electrical repairs question came from: Greg, from Los Angeles, California.

Dave’s Reply:
Thanks for your home generator wiring question Greg.

Identify the Condition of Electrical Circuits to Prepare for a Generator

When planning to install a generator it is best to survey the existing electrical system of the home to avoid any problems and have a safe and functional system when generator power is needed. As we see from this photo and the condition of the electrical circuits as described there are some areas of concern that will need to be addressed.

Skill Level: Advanced – Licensed Electrical Contractor, Not Recommended for Homeowners, however make sure to inform the electrician about the questionable electrical wiring that has been discovered and any additional wiring that has been installed.
Tools Required: Electricians pouch of hand tools and the various power tools necessary for installing the generator and transfer switch.
Estimated Time: Depends on the type and size of the generator and transfer switch and the available access to the project area. Additional electrical violations or corrections will need to be completed.
Precaution: Any existing electrical wiring within the immediate area that may interfere with the installation of the transfer switch may need to be relocated if necessary. The selection of the transfer switch or generator connection or generator circuit panel will affect the over all project.
Important: Installing a generator, transfer switch or generator panel must be well thought out and performed with a permit with all work being inspected. Be aware that generator types and connection methods may be regulated by local ordinances and or building authorities.

Identifying any Electrical Concerns

As stated in the question and I have seen in the photo there has been previous electrical work performed which needs to be inspected and corrections as needed, including mixed wire gauges, improper circuit breakers for the brand of panel, correct size of the circuit breakers for each circuit, and most of all identify each circuit to understand where it goes what it feeds and if necessary make the appropriate corrections.
The electrical panel panel itself appears to be in good shape, however the electrical circuits and wiring methods need to be inspected and dealt with.

The method selected to connect the generator power to the home will determine what additional electrical wiring and equipment will be required. When installing most circuit breaker interlocks a transfer switch will not be required, and the same is true for generator circuit panels.

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