14 of 20 - Installing the Backup Loads Subpanel and Selecting Critical BreakersLoad

Critical loads are loads that should be supported by a backup system whenever the grid goes down.  

These loads typically include the refrigerator, lights, and outlets (which usually means the router as well).  


! Important: The entire main service panel cannot be backed up with this system. The backup system is able to generate 20A maximum so the critical loads must not exceed 20A total.  


The circuit breakers that power these loads are found in the main service panel or a sub-panel within the home. 

These circuit breakers must be identified and then relocated into the Backup Loads Panel (BLP).  

The BLP will be energized by the inverter and battery in the event that grid power is lost.  


Therefore, if the breakers for the fridge, lights, & outlets get moved into the BLP, they will not lose power during an outage. 


Most likely only two breakers will be moved over: one 15A breaker for the fridge and one 15A breaker for lights and outlets 


The main service panel/sub-panel will likely have a diagram indicating what each circuit breakers power. Use this to determine which breakers power the refrigerator and the lights. 


If no diagram is present, then use this old-fashioned method of determining what each circuit breaker energizes: 


  1. Turn on all of the lights in the house 
  2. Turn off one circuit breaker at a time - going through the house and identifying what lost power when that circuit breaker got turned off 
  3. Note: this is easier with two people working together 
  4. The lights and fridge should be quickly identified  
  5. Make a note as to which breakers are the ones that need to be relocated into the BLP - make a diagram on a sheet of paper or make labels using blank white stickers that can be placed near the breakers  
  6. Keep in mind: the BLP can only support up to 20A so only a few small breakers can be supported 
Victor is the author of this solution article.

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