Charger Setup 101: Power

What you need to set up AC charging at your business

As I mentioned in the Business Q&A, all you really need to charge an EV is a parking spot and an outlet. But to be effective as a charging stop, you should know a few details about the ways that EVs can charge. With this knowledge you will know what to expect from your equipment, and can accurately inform EV drivers, many of whom are also new to this whole 'driving electric' thing. If any EV charging terms below are unfamiliar, you can refer to the glossary page for clarification.

Blanket disclaimer: this page contains general guidelines. You should always consult a qualified electrician before making changes to your wiring, and to make sure your electrical hardware is up to code and in good condition.

Power needs

Keep in mind that US electrical outlets, wiring and breakers are rated for a certain maximum amperage and voltage, and an "80% rule" applies to continuous loads for safety. That means a 50 amp circuit breaker can safely sustain a continuous load of 40 amps, a 15-amp circuit can sustain 12 amps, etc. Electric vehicles and charging systems know this as well and are designed for it, so a building that is properly up to legal electrical code will have no more problem with an EV than any other electrical device. But EVs do like to draw as much power as possible for charging, so it is most helpful to have a charging outlet on a dedicated circuit, so that an additional load from some other device doesn't trip your breaker when the EV is already drawing the maximum.  Keep the 80% rule in mind for the figures listed below.

1a. Level 1 overview
Level 1 charging is the most basic level of AC charging, available from a regular 120-volt wall outlet. All EVs come with a connector that can enable this level of charging, at the least. However, it is very slow. A normal 120v wall outlet is rated for 15 amps, and (due to the 80% rule) can safely output a sustained maximum of 12 amps. This equates to 1.44kW and will add just 3 to 5 miles of charge per hour. EV drivers will generally avoid this type of plug because it is so slow, but it can be an absolute life-saver if there are unexpected problems on a trip! A slow charge is very much preferable to becoming stranded due to a planned charging stop being unavailable, or due to a misjudgement of miles or energy usage. A driver that stops to use your 120v plug may arrive quite stressed, but could be the most appreciative EV driver you ever meet!

1b. What you need for Level 1
A regular wall plug is all you need for this connection, but it should be on a dedicated circuit with its own 15 amp breaker, or at least on a circuit that doesn't have very much else on it, and nothing else with a continuous power draw. All EVs come with a connector that can be used at a regular wall plug, and an EV traveler should be expected to bring theirs along with them on a trip, even if only as a backup in case higher-capacity chargers are not available. An EV connector will generally try to draw the full 12 amps from your outlet, so you don't want something else to turn on that will trip the breaker. For safety, some EVs are designed to draw only 8 amps by default from this type of outlet, to allow for connection in older homes with poor wiring or other uncertain situations. But as a rule you should assume that an EV will attempt to draw the full 12 amps. Make sure your wiring and plug are in good condition, including a cover for the plug if it will be exposed to inclement weather. A faulty or dodgy outlet will generate a lot of heat, presenting a fire danger in addition to wasting energy and slowing down charging. Covers can also be used for security, as they can be purchased with locking ability so that they can be made inaccessible outside of business hours, if needed.

If your 120v outlet is some distance from available parking, it is ok to provide an extension cord, but it needs to be a beefy 3-prong cord, fully rated for 15 amps. A 20-foot extension cord needs to be 10 AWG thickness or better. A longer run must be even thicker, so you will probably want to stick to one cord of 20 feet or less. The connector that an EV driver brings with them will likely be 15-20 feet, so an outlet reasonably close to parking should reach without additional extensions.


2a. Level 2 overview
Level 2 charging is 240 volts AC and has a wide range of options, but as a small business providing charging for travelers, you will want to focus on just a few. The minimum charging level that can be considered Level 2 is 240 volts at 16 amps, which can be achieved with an outlet on a 20-amp breaker. (80% rule again!) While 20 amps is fine for a home charging installation where an EV charges overnight, it is not terribly fast and a small business would be better served by an outlet or charging station with more amperage. A 50 amp connection is the most common type for charging, and is enough to reach maximum AC charging speed on nearly all EVs.

2b. What you need for Level 2: Wall outlet method
While many types of wall outlets are available, the most common 240-volt outlet in use for EV charging is the NEMA 14-50, and installing one will provide the most flexibility for visitors to charge. It is a 50 amp outlet and so should be served by a 50 amp breaker. If you are not familiar with electrical work, you should definitely consult an electrician to assess your ability to add a 50 amp breaker and outlet, or if you have existing wiring that could be used. If you have the capacity available, the greatest determinant of cost will be how far the wiring must be run to reach a place where your customer can park and plug in. Typically, a new breaker and a short run of wiring to a NEMA 14-50 outlet can cost a few hundred dollars.

If you already have a NEMA 14-50 outlet located near a parking area, congratulations! Little or no modification may be needed to make it available to EV drivers. If your outlet has another type of plug such as NEMA 10-50 or 6-50, you should consider having an electrician replace the outlet with a 14-50 and then buy an adapter (about $60) for the use of any personal equipment that uses the old plug style. For an RV park it is especially easy to cater to EVs: the NEMA 14-50 is one of the most common outlets used for RV hookups, and an EV can plug in just like an RV.

The 40 amp continuous output that a NEMA 14-50 outlet can provide is more than enough to meet the maximum internal charge rate of almost all EVs. Even for a Tesla which can AC charge faster than this, the NEMA 14-50 is an appropriate outlet; all new Teslas are supplied with a mobile connector for which a 14-50 plug is cheaply available. A prepared Tesla owner should be bringing this mobile connector with them on a trip.

2c. What you need for Level 2: J1772 method
If you want to take the next step above a NEMA 14-50 outlet, a dedicated J1772 EVSE unit will give you a higher profile and an added level of convenience for an EV traveler, as they will not need to unpack their own equipment to charge at your establishment. This can be done as a later upgrade using your 14-50 outlet, or you can skip the outlet stage altogether and buy a hard-wired J1772 unit. All EVs sold in the US other than Tesla have a J1772 inlet for charging. Teslas use their own type of connector, but an adapter for J1772 is included with every vehicle. An EVSE unit (commonly called an EV charger) with J1772 connector can be purchased for as little as $200.

32 amps: There are many consumer-level EVSE units available from Amazon and other online retailers. Typical 32-amp units have a NEMA 14-50 plug and an output of 32 amps, with prices starting around $350. This output is less than the full 40 amp capability of a 14-50 outlet, but 32 amps is at or above the maximum charge rate for most electric vehicles, and can add 20 miles or more per hour of charging for EVs that can accept this rate.

16 amps: The cheapest units, which cost around $200, normally output just 16 amps, so they're less than ideal. But they do have a good use: if you are unable to install a 50 amp outlet due to limited capacity, 20 amps may be within reach. In that case you can install a NEMA 6-20 outlet, paired with one of these budget EVSE units, and achieve a higher output than a standard outlet - about 11 miles per hour of charging, compared to just 3-5 miles for a 120-volt wall outlet.

There are many options for charging units in the $500-800 range, that are more robust than the budget units and can use your NEMA 14-50 outlet in the same way. Some are waterproof or otherwise designed for outdoor use, and have features such as internet and/or smartphone connectivity. Major brands include Clipper Creek, ChargePoint, and JuiceBox. Many of these units are also sold in a version without a plug, so they can instead be hard-wired into your building's power without the use of an outlet.

2d. What you need for Level 2: Tesla method
As the largest manufacturer of electric vehicles, Tesla has a huge installed base of cars - over 200,000 are already on the road in the US alone. Teslas have a much larger battery capacity than most other EVs and so do not need to charge as often, but they still need to charge. In addition to Tesla's network of high-speed Superchargers, there is a secondary network of 240-volt AC chargers that Tesla calls Destination Chargers. These units are made by Tesla, and are available to hotels, shopping centers, tourist attractions, retail stores, etc. A Tesla connector is different than the J1772 connector used by other EVs, and while Tesla supplies a J1772 adapter so that their cars can use J1772 chargers, the reverse is not true - while there is a third party adapter allowing other EVs to use a Tesla charger, it is expensive (over $200) and not widely owned.

The greatest advantage of a Tesla Destination Charger, in addition to the large installed base of cars, is that Tesla often provides them to establishments free of charge. Tesla's bigger goal is the advancement of electric transportation, and they have been known to give away not just their own chargers, but sometimes to pay for an additional J1772 unit for the use of other EVs, and even on rare occasions to pay for installation costs. This is frankly an AMAZING option that every small business should be eager to explore. After installation there are typically no strings attached to the units installed under this program. Tesla makes the destination charger locations available to every Tesla owner through its in-car navigation system. I strongly urge every small business and attraction to contact Tesla via their web site, to inquire about the possibility of joining Tesla's Destination Charger network. Many classic stops and attractions along Route 66 are already participating, including the Blue Swallow Motel in Tucumcari, NM, La Posada in Winslow, AZ and the Heart of Route 66 Auto Museum in Sapulpa, OK.

Equipment safety and security

It goes without saying that you should keep your outlets and charging equipment in good working order. Reliability is very important, especially in these early years of EV travel where there may not be many chargers to choose from in non-urban areas. To protect outdoor outlets against the weather, they should have covers or enclosures appropriate to their exposure. J1772 charging equipment should also be covered or housed in an enclosure that can keep it out of the weather, especially if you intend to use a consumer-level unit. Some of the more expensive units are designed for outdoor use and so may require less in the way of protection.

If security is a concern, there are lockable outlet covers and enclosures available. With a key or combination your equipment can be made accessible only upon request or during your operating hours. For a consumer-level J1772 unit using a plug, it may be easiest to keep it inside when not in use, while labeling the outlet with a message that it is available to customers upon request.


Let me know at mike@ElectricRoute66.com if you have questions or comments about this page. Now that you have an overview of your power options, let's move on to Charger Setup 102: Parking & Pricing!

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