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5KV class distribution and EVs

Doug Houseman's picture
Visionary and innovator in the utility industry and grid modernization Burns & McDonnell

I have a broad background in utilities and energy. I worked for Capgemini in the Energy Practice for more than 15 years. During that time I rose to the position of CTO of the 12,000 person...

  • Member since 2017
  • 253 items added with 90,616 views
  • Jan 20, 2022

3600-to-5400-volt distribution primary voltage was the standard in much of the United States from 1934 to 1960. Many of these substations have been upgrades, and the distribution lines, upgrading the voltage did not happen many utilities.

On average, utilities that had significant amounts of 5KV class distribution in 1970, still have most of it. It is not unusual for utilities to still have 50% of their customers on 5KV circuits.

A 5KV class distribution circuit is designed to deliver about 3000 Kilowatts (KW) of energy. The conductor tends to be small, and so the circuit is restricted in the amperage that it can operate at continuously.

It is not unusual for a 5KV class suburban circuit to feed 1000 residences. It is more unusual to see 5,000 residences, it is not unheard of.

The typical US suburban household has just over 2 vehicles.
Previously the standard level 2 (garage charger) was between 7 and 8 KW, so 5Kv circuit, with no other load could handle about 800-1200 chargers, but many are at 80% of maximum on hot and cold nights, reducing that to about 300.

Now Ford, GM and others have introduced 20KW Level 2 chargers as standard. On that same circuit, with no other load that is 450 chargers, and with an 80% load, that drops to about 100.
For suburban charging, even with scheduled times to charge it does not.

Is it time to get serious about higher voltages?

Jim Stack's picture
Jim Stack on Jan 21, 2022

Many home EV chargers are 6 kW. Yet most Tesla owners want the higher 10 to 20 kW charger. In the summer in a hot garage that makes a heat Island that uses a lot just to cool the Tesla battery. I live to charge nice and slow at 3 kW so it doesn't waste a lot of energy running fans and trying to cool the battery. It seems very wasteful to charge fats. In fact Off Peak charge with the car parked out in the open air is the most efficient charging. 

Doug Houseman's picture
Thank Doug for the Post!
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