Adding 200A subpanel

[Procyon]

Hey everyone, hoping to get some advice on the most economical way to add a 200A subpanel.

Existing system is a 200amp main distribution exterior panel that only has one tap (4 available) used to feed a 200A interior main breaker box (~50ft away)

The main breaker box has only one circuit left open out of 40 total circuits. Most are taken up from individual lighting and outlet branch circuits.

The home still has an unfinished basement that will require several electrical circuits, hvac, and would like the possibility of adding on a pool at a later date.

From experience and research there are two possible ways to go about this.

The entire home is protected by the 200A main on exterior and then the interior breaker also has a redundant 200A breaker. A load calc puts me around 115A right now.

First method would be to run a new 4/0 AL feed from the exterior panel to the new 200A panel (~50ft away)

Second method would be to change over a few circuits from exisitng panel to the new panel and install passthrough lugs from existing panel to feed subpanel (~2 ft away)

Leaning towards second method due to cost of feeder wire and for simplicity. Codes here are 2018 International Residential Code and 2017 NEC.

Anyone have constructive input on this?

Thanks,
S

 

[havasu]

If I am reading your post right, you can not install a 200A sub panel from a 200A main.

 

[user 4883]

I've seen these exterior breakers with a redundant breaker inside.
IMO, they have affectively created a sub-panel.
So you'd be looking at running a sub-panel off your sub-panel.
I'd be interested how this pans out.

 

[Hamberg]

Hey everyone, hoping to get some advice on the most economical way to add a 200A subpanel...

Left out some details, like (inside) panel manufacture, max ampacity, etc.

BUT, here is one item that will sway your decision. If you updated (change out) and or add another panel, you'll need to pull a permit (or if you just want to do it right) which means you'll need to upgrade to current (NEC 2017, 2020) standards.

90% of those old circuits will need to be AFCI/GFCI breakers at $50 - $75 a pop.

May be easier/less expensive to (100A) sub-panel off of the interior for the basement. As for the pool, I'd let the pool contractor figure that one, 95% of the time it's priced out as a whole install anyway. Plus, assuming you have NG, it would only be an ignition circuit (20A max) and most pool pumps are 20A max as well.