[FAQ] - EV Chargers - common misconceptions - what is an EVSE?

[USMA81]

One other thought. The anticipated amperage draw affects the size (gauge) of the wire coming from the electrical panel to the hardwired charger. The change in wire size sometimes is important because the wire gets really stiff at lower gauge sizes (thicker wire). This might make it harder for your electrician to install the thicker wire in confined spaces or around tight bends.

A 40 amp circuit @ 240 volts will deliver 9.6 kW, but if you building in higher amperage for the future, then the gauge will go down. I’m not sure how load sharing would affect the gauge, but it also might be something to consider. Possibly Goldtrom can weigh in on all of this.

Here is what Perplexity AI fed back to me when I asked about this for my home state:

For typical (short run, under 100 feet) circuits in Arizona, the required wire gauge per the National Electrical Code (NEC) for copper conductors is:
• 40 amps: 8 AWG copper
• 50 amps: 6 AWG copper
• 60 amps: 4 AWG copper
For aluminum wire, use one size larger than copper:
• 40 amps: 6 AWG aluminum
• 50 amps: 4 AWG aluminum
• 60 amps: 3 AWG aluminum (sometimes 2 AWG is specified because aluminum has lower conductivity).
If your circuit run is over 100 feet or will be exposed to high ambient temperatures (very common in Arizona attics or outdoors), it’s recommended to size up one gauge to reduce voltage drop and account for derating due to heat.
Always verify with local building codes and a licensed electrician.

Sponsored

 

[daveo4EV]

One other thought. The anticipated amperage draw affects the size (gauge) of the wire coming from the electrical panel to the hardwired charger. The change in wire size sometimes is important because the wire gets really stiff at lower gauge sizes (thicker wire). This might make it harder for your electrician to install the thicker wire in confined spaces or around tight bends.

A 40 amp circuit @ 240 volts will deliver 9.6 kW, but if you building in higher amperage for the future, then the gauge will go down. I’m not sure how load sharing would affect the gauge, but it also might be something to consider. Possibly Goldtrom can weigh in on all of this.

Here is what Perplexity AI fed back to me when I asked about this for my home state:

For typical (short run, under 100 feet) circuits in Arizona, the required wire gauge per the National Electrical Code (NEC) for copper conductors is:
• 40 amps: 8 AWG copper
• 50 amps: 6 AWG copper
• 60 amps: 4 AWG copper
For aluminum wire, use one size larger than copper:
• 40 amps: 6 AWG aluminum
• 50 amps: 4 AWG aluminum
• 60 amps: 3 AWG aluminum (sometimes 2 AWG is specified because aluminum has lower conductivity).
If your circuit run is over 100 feet or will be exposed to high ambient temperatures (very common in Arizona attics or outdoors), it’s recommended to size up one gauge to reduce voltage drop and account for derating due to heat.
Always verify with local building codes and a licensed electrician.

excellent post - I found this on the internet also - it's a good rough guide - as always confirm with a licensed and bonded electrician familiar with local building codes…

in my case with load sharing - I have a 100 amp sub-panel being fed by appropriate 100 amp rated wire - and each of the 3 Tesla EVSE's are on their own 60 amp breaker with appropriate wire feeding each EVSE - while there is 100/80 amps total capacity - each EVSE can only deliver a max of 60/48 amps - so the wire feeding that single EVSE only needs to be appropriate gauge for it's single potential maximum draw.

 

[daveo4EV]

If you are buying an EVSE, the embedded video in an earlier post is valuable to watch. For me, the Porsche charger was silly expensive and I found online complaints about it. I don’t need load sharing because I only need to charge one EV at a time. After watching the video, I bought the ChargePoint charger. No regrets. YMMV.

I personally feel that having an EVSE hardwired is necessary. I’d not want a secondary cable running from the charger to a plug in the wall. There have been some reported electrical issues, fires, when the outlet is not high quality. These 240 V NA outlets are the same as those in the home that supply electricity to a clothes dryer / oven / cooktop, but the EVSE will pull 40 amps much longer that the typical run time of a cycle on these other appliances. If there is a bad connection or dubious wall socket design / materials, it could result in a bad day. It is a low risk, but one I chose not to take by installing the ChargePoint charger.

you are 100% correct - EVSE's should _NOT_ be run on normal residential NEMA sockets…

Porsche came to realize this in about 2022 and published an official "guide" to proper installation for their EVSE - you need to use a commerical/EV rated NEMA socket…

all the gory details from Dec. of 2022 can be seen in the following links:

https://www.taycanforum.com/forum/t...-related-porsche-ntsb-article-analysis.13902/
https://static.nhtsa.gov/odi/tsbs/2022/MC-10222530-0001.pdf

two things of interest came out in that Porsche published tech bulletin:

For example, the following receptacles are recommended for their industrial quality and ability to handle high current with minimal electrical resistance for long periods of time:

• Hubbell HBL9450A = NEMA 14-50 Receptacle (4-wire)
• Hubbell HBL9367 = NEMA 6-50 Receptacle (3-wire)

A 50-amp branch circuit should use minimum 6 AWG, 90°C-rated copper wire for conductors supplyinglevel 2 Porsche charging hardware plugged with a NEMA 14-50 or 6-50 supply cable. Receptacle terminal screws must be tightened to manufacturer specifications. The use of ferrules on the supply conductor wiring is recommended to further safeguard the circuit connection at the receptacle

General Precautions on (125V) Supply Cable Use

The “domestic” (125V) supply cable is provided for emergency use only, and should not be used by customers for daily home charging. Please discuss installation and use of a suitable 250V circuit with all customers.

Information Caution
…
When used, it is recommended to limit 125V charging to a maximum of approximately 12 hours. Charge only to a minimum needed get to a nearest High-Power Charger (HPC) or DC Charger for recharging.

Porsche's recommendations at the time echo'd existing best practices from other EV manufacturers but the distain for L1 charging was "new" and never fully explained…

reasonable speculation about L1 charging postulates that it's about "hours of continuous use" - i.e there are components in the AC/DC charging chain that have known MTBF's - and if you are always charging using L1 the number of hours these components are kept "awake" to charge the battery is quite large over the expected lifetime of the battery.

using Porsche's own warranty as a guide - it's an 8 year/100,000 mile warranty - if you use 100,000 miles as the metric and stipulate that an EV is 3 miles/kWh - that means in 100,000 miles you will have run 33,333 kWh's "through" the battery to drive that much distance - let's call it 35,000 kWh's

replenishing 35,000 kWh's at 1.44 kW charge rate (120V L1 15/12 amp charging) is 24,305 hours of charging - or 1012 days or 2.77 years of "keeping everything awake during a charging session"

replenishing the same 35,000 kWh's at 9.6 kW charge rate (240V L2 50/40 amp charging) is 3,645 hours or 151 days of continuous use…

as you can see there is quite a bit of difference in 24,000 hours vs. 3600 hours in terms of "life time" awake time for charging at L1 vs. L2 charging speeds - there could be some element of the Taycan's charging system that has components only rated for 10,000-15,000 MTBF - so Porsche doesn't want those component "awake" and operational for that long of a period of time…

as I said this is only speculation - Porsche never explained their rational for limiting L1 charging use…

 

[Paris92]

They used hard wall conduit for running my wiring, per code here. I needed an EMS module as part of my system (my incoming service is basically maxed out.) Emporia Pro was my choice because of the EMS module they have, and it also monitors my solar feed and sends any excess power to the car when/if required.

 

[daveo4EV]

They used hard wall conduit for running my wiring, per code here. I needed an EMS module as part of my system (my incoming service is basically maxed out.) Emporia Pro was my choice because of the EMS module they have, and it also monitors my solar feed and sends any excess power to the car when/if required.

lovely install - super clean…

 

[Paris92]

lovely install - super clean…

They knew what they were doing... and I watched them the entire time... haha. Actually it was a really good, professional installer that did the work. Very pleased, and so was the city inspector.

 

[whitex]

Hi @daveo4EV - very helpful for the ill initiated / informed.

PMCC and PMC+ are rock solid outside NA - my PMCC has been faultless since new 2021 for example.and still going strong today.

They don't make smaller, lighter, more cable and easier to use EVSEs in the rest of the world? Oh wait, you did say solid as a rock (I am paraphrasing)

Sponsored