AboutRick Miell Expertise Past County electrical inspector, hold St. of Colorado Master license, will try to answer any electrical question with Code related answers.
Experience State of Colorado Master Electrician. Past County Electricial Inspector (15 years)
Question We recently had an electrician to our house to complete some work and he suggested that we should upgrade our system from 200 amps to 300 or 400 amps. The house is completely electric and we have basically run out of room in our main breaker box.
The house is two story and is approximately 2600 sq feet. We have two heat pumps (one on each floor) with 15kw heater bands in each. We also have an electric hot water heater, double oven, range top with 5 elements as well as a dishwasher, disposal and 2 refrigerators. We also have a barn which is connected to the house and will be adding a hottub and deck lights next spring.
Because the electrician is in one that we would have install any upgrade, I am trying to get a few questions answered first. I do not want to pay for something that may not be needed.
Using some online tools, I have done a basic load calculation and we are approaching 200 amps. If we decide to do this, I will also have him do one to get an exact number.
I have been told on another site that there is no such thing as a true 300A service. It is simply a 400A service fused down to 300A. Is this correct?
In addition, I have been told the best upgrade would be to go to a 320A continuous/400A max service with 2 200 amps panels. I know you do not have all of the details. But what would you suggest?
Thank you.
Answer Hi Jeff.
The statement about there being no true 300 amp service is correct, because there is no equipment rated only 300 amps. You have to install 400amp equipment and reduce the overcurrent device to 300 if that is what you want.
The double 200amp setup is the most common, and most utilities will allow this to be fed from a normal feed through meter. Some utilities require that any load over 200 amps utilize a ct metering arrangment, which means the power is not run directly through a meter. this setup usually uses a extra cabinet mounted next to the panel, in which the utility places their cts to capture a certain portion of the load, and allowing that current to show up on a special type of meter. The readings of your consumption would be the same, just getting it through a different method than the normal residential type of metering.
If you are sure that the calculations show a load close to or over 200 amps, I would suggest the 320/400amp setup, if your utility allows it.
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