Larger subpanel

My house has a standalone main disconnect box, followed by a Federal Pacific stab-lok 100A panel. Previous owner needed more breakers, and added a 2 breaker subpanel right next to main panel, fed directly off of the bus of the main panel, i.e. not fed by a breaker. Books all show subpanels fed via a breaker, but intuitively the arrangement I have seems alright. Is it? Predictably, I need more breakers, so could I replace this 2 breaker subpanel with a 6 or 8 breaker subpanel and use the same feed method? (I realize that the other choice is to install an entirely new, larger, modern panel.) Thanks for all the help on this forum! Robert

 

If I were you, I would replace the Federal Pacific main panel with a larger panel. This way you will have one panel. federal Pacific panels have issues that you would be best off not having to deal with or concern yourself with.

 

I believe ( John or Racraft may correct me) if this is a "feed thru" off the busses in the main panel make sure these feeders are amp rated same as the main breaker (100 AMP I assume). Probably 3 or 4 awg copper or 2 awg Al. The main breaker would be their overcurrent protection. I see nothing wrong with your plan other than be sure your demand load doesnt exceed the rating of the 100 amp panel.

 

When installing a sub panel does the source have to come from a brealer or the main panels entry legs??
Jojn1