Aug 24, 2022

Do we really need 200A electrical service? POMCube is the answer for you

Do we really need 200A electrical service? POMCube is the answer for you

By POMCube | Aug 24, 2022 | Pageviews:331
When the electricity consumption is greater than the energy generated, the missing part of the energy will come from the battery storage, so the energy stored in the battery will drop.

According to the POMCube understands,Most of the new housing built after 2000 has 200A of electricity access, but do we really need 200A? Many homes built in the 1970s don’t necessarily have a lot fewer appliances than those homes built after 2000, but why are such homes all have 70A grid connection?

I believe that, only after carefully understanding the design of the distribution grid, one can understand the rationale for such a difference. Originally, the design of the distribution grid will have each 7MVA feeder line servicing 400 homes. Therefore, each home is actually designed to have a continuous draw of 73A (roughly 17.5kVA).

If you have the opportunity to go to the construction site of a new housing project, you may wish to take a closer look at how many homes each curbside transformer really serves, According to my observations over the years, a distribution transformer, usually installed curbside, only power 5 to 7 homes in California. In Texas, this number is significantly reduced to 3, and the reason, I guess, is that the size of the houses in Texas is relatively large, and the use of air conditioning is often longer, so the number of houses corresponding to a distribution transformer is only half that of California.

As for the nominal power of these distributed transformers, it is usually 50kVA. We’ve seen 75kVA on a few occasions, and we’ve seen a very small number of 25KVA (single-family pole mount). Therefore, we can consider most of them to be 50KVA.

In this way, a standard distribution transformer in Texas is used to support three houses, which is in line with the design of the general distribution grid. It’s however surprising that California has only 40A ~ 50A of planned current (@240V) per house.

What is the concept of a 50KVA transformer? 50KVA is actually 200A (~208A) at 240V. That is, in California, every 5 homes actually share a maximum continuous current of 200A, so the maximum continuous power per household is only 40A! If every household buys at least one Tesla EV and charges it together in the early hours of the morning, then the transformer is likely to be overload protected.  

So why are most new homes having 200A electricity service?

The only reason we need 200A service is inrush current. The most common of which triggers inrush current is central air conditioning units, especially those with 4 or 5 tons of single-speed compressor. The water pump will be another cause of inrush current.

The good news is POMCube now have variable speed (VFD) compressors and motors that demand very little inrush current and VFD, often referred to by manufacturers as “inverter based”, is almost the default option these days for many new appliances (mini splits, washer and dryer, and refrigerator). The bad news is, of course, all the existing appliances are still functioning and producing inrush current.

Therefore, the 200A grid service is actually 50A ~ 70A continuous current. Please stop dwelling on the must-have requirement of the 200A concurrent current. Instead, we should confirm whether the system design can support the maximum inrush current. If not, we should install the soft starters or VFD controllers to reduce the inrush current so that we don’t have to spend the money buying the system supporting a 200A grid connection but, in reality, we won’t need them in 5 years.

The POMCube team has advanced technologies and concepts such as independent research and development, independent innovation, Internet security, energymanagement, intelligent control and big data analysis. Through professional knowledge, it helps users create an energy-saving energy reuse system,save electricity costs, reduce carbon dioxide emissions, reduce Greenhouse effect.

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