# Upgrading 400A service to 600A



## Destarah (Feb 18, 2016)

Looks like I am stepping into an interesting project. Original house was 6000 sqft bungalow and at this point in the "renovation" they have arrived at 21000 sqft. Still using the original 400A service fed from a 50kVA transformer by the LDC.
I was brought in by a landscaping company who is looking to tile the 3500 sqft indoor pool area and wants me to quote on lighting and such for that.
Now they are also quoting to tile about 5000 sqft of the basement, and want it all heated. I look at the existing service which has:
1 x 200A panel
3 x 100A panels
1 x 400A panel that was added to service the mechanical for the pool area!

So, according to my math they have 900A worth of panels. I realize that doesn't mean much in the grand scheme of demand and load, but the 400A panel for the mechanical area has a 225A breaker in it that is feeding the phase inverter for the Dry-a-tron (3 phase, 100A unit) ... methinks the 400A service is already overloaded without me adding 34kW of floor heat.

Would I be best served to have calcs done by an engineer so that I have something with a stamp on it to present to the owner? I am pretty confident that the LDC will play ball and want to upgrade that transformer anyways ...

Any thoughts or suggestions on things I need to consider would be much appreciated, this looks to be a bigger bite than I am used to chewing on.


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## Going_Commando (Oct 1, 2011)

Grab your code book, do a load calc, and see where you land. 5000 sq ft of electric floor heat is going to chew some serious power, as most of it runs anywhere from 8-12 w/sq ft.


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