|reply to tschmidt |
Re: The renovation continues ... today new 400 amp service!
said by tschmidt:I'm trying to recall exactly what the POCO guy said about the installation here. We're on a 15kW transformer by ourselves. Service for house is 200A. Seems he told me they figure it a bit differently than you did as 15kW / 120V = 125A, and that is *per leg*, so we would essentially have excess capacity with the current configuration. This of course assumes perfect load balancing.
Being the good engineer that I am felt obligated to point out that 200A x 240V is 48 KW. The supervisor smiled knowingly and said that was true but transformer has tremendous overload capacity.
Now, I may be wrong on that, its been awhile since that conversation came up. Just throwing it out for those who know more than me to cuss and discuss...
said by mattmag:Yes, its wrong. 15kVA / 240V = 62.5A. Total. Or per leg. Makes no difference, there is no other way to do the math.
We're on a 15kW transformer by ourselves. Service for house is 200A. Seems he told me they figure it a bit differently than you did as 15kW / 120V = 125A, and that is *per leg*...Now, I may be wrong on that
This could be exceeded when necessary, the transformer can be overloaded at a reduction of its life. 15kVA works fine for most homes - on average. That is why utilities often put up to 4 on one 25kVA transformer, which can basically only provide 100A total at rated load.
The OP's 400A service? Note the transformer its fed off of. 50kVA at best, and its shared. It puts out 200A - shared - at full rated load. But a 400A service certainly makes for a nice thread, more than most of us could post if we were trying to impress people with our service.