# 400 amp to 600 amp



## kbe (Aug 11, 2009)

Stan , Guy love the show. Long time listner first time caller. 

Looking at creative ways to upgrade an exisitng 400 amp residential service to 600 amp for new geothermal heating system. Load calcs = 571 amp needed for the 12,500 square foot house it is being added to.

1st idea- new 4" conduit for parallel feeds with existing 4" conduit both to land in poco supplied CT cabinet. 

From ct cabinet feed existing 400 amp meter / main comb. Which has 2 - 200 amp disconnects in it feeding sub panels inside house and an integrated 200 amp panel with 2- 100 amp 240 volt branch circuits feeding sub panels inside.

Fom Ct cabinet feed new 200 amp meter/main combo and run new 200 amp branch circuit to new 200 amp subpanel in geothermal equipment room . geothermal gets its own meter 

under the six switch rule ,disconnects grouped together, single service 

I know I am missing some details , but any major flaws in this design that I am overlooking. Too many feeders entering the building or are they Branch circuits?


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## TOOL_5150 (Aug 27, 2007)

sounds like a good idea, but parallel feeds are supposed to be the same length. Unless you are going to pull out the existing service and measure it, I think you might have a tough time proving the existing and new wires are the same length.

~Matt


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## augie47 (May 4, 2009)

existing 4" should be able to handle 600 amp service with having to add second conduit... parallel 400s for example...


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## kbe (Aug 11, 2009)

*only one meter*

Meters are gone, just one on the ct.(duh) The poco will not supply the 400mcm copper but will supply the Al wire for parallel runs and the run is almost 200 feet. We relocated the existing 4" 2 years ago so we know its length and location so making the new one the same length shouldn't be an issue. Inspector said watch the 240 tap rules, wasn't planning on taping unless I have too. 

So now planning on setting seperate feeds and disconnects for each panel Which I think would be cheaper than buying an exterior rated 600 amp panel with a 200 amp and 400 amp breaker in it. But am concerened The inspector wil say I now have two feeds for the same building. Actually I could skip the disconnects and still be under the six switch rule. 
I have done 800 amp residential services, but never a 600 amp so if some one could explain how they usually do them it migh clear things up for me. Thanks for your help


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## drsparky (Nov 13, 2008)

kbe said:


> Meters are gone, just one on the ct.(duh) The poco will not supply the 400mcm copper but will supply the Al wire for parallel runs and the run is almost 200 feet. We relocated the existing 4" 2 years ago so we know its length and location so making the new one the same length shouldn't be an issue. Inspector said watch the 240 tap rules, wasn't planning on taping unless I have too.
> 
> So now planning on setting seperate feeds and disconnects for each panel Which I think would be cheaper than buying an exterior rated 600 amp panel with a 200 amp and 400 amp breaker in it. But am concerened The inspector wil say I now have two feeds for the same building. Actually I could skip the disconnects and still be under the six switch rule.
> I have done 800 amp residential services, but never a 600 amp so if some one could explain how they usually do them it migh clear things up for me. Thanks for your help


I hate to be a stick in the mud but, I doubt you will get the wires close enough to properly split the load. When you have it finished place an amp meter on each conductor. Post the results, I am very curious if it can be done.


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