[RE-wrenches] backfeeding "six disconnect" panel

[Scott McCalmont]

If you backfeed a new breaker added to the top bus, it is a supply-side connection. The bus bars in the top are exposed to the full fault current capacity of the utility drop. You wouldn't be limited by the 120% exception.

Or you can backfeed a breaker on the bottom bus, and then it is a load-side connection. The main breaker for this subpanel would be the 60 A breaker in the top. The 120% rule applies.

Scott

On Oct 28, 2010, at 5:19 PM, Dana Brandt wrote:

> Hi everyone,
> 
> I'm working on two systems for homes that have the old style breaker panels with no single main breaker. Instead, they have six breakers in the upper part of the panel each labeled "main breaker," which satisfies the six disconnect rule. The bus bar is split, with one of the six upper breakers (60A) feeding a separate bus in the lower half of the panel. It appears that the upper bus is rated for 200A, and the lower at 100A.  The sum of the main breakers does not exceed the 200A rating of the upper bus. There are spare breaker slots on both the top and bottom buses. How do I deal with 690.64 (B) (2) when there's no main breaker? 
> 
> Thanks!
> 
> Dana
> 
> Dana Brandt
> Ecotech Energy Systems, LLC
> www.ecotechenergy.com
> dana at ecotechenergy.com
> 360.510.0433
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