Quick electrical wiring question, derating break for Level 2 charger

[Denwood]

You don’t need to spend a ton on wall mounted EVSEs. Our EV came with an OEM EVSE which will charge at 12A/120V or 32A/240V. I picked up a spare (“portable”) EVSE (~$235 CAD) that does 16A/120V or 16A/240V and it’s been all that we need. 16A/240 adds 10% charge per hour.

120V charging is pretty slow as OEM EVSE units will limit to 12 amps, and due to the car’s electronics overhead (about 300 watts in my case), is not as efficient as charging at 240V. If in a cold climate, 120V preconditioning is also not ideal as you may only have 800-900 watts available to preheat. At -20C it is not sufficient.

A NEMA 14-50 is plenty for home charging for most EVs out there. Remember that EVs are getting more efficient as well. If you have a Hummer EV (don’t get me started) then ya, you’ll need a lot more.

 

[Denwood]

@TT_Vert you can check out this interactive charging tool to give you an idea of current/voltage and range at various charge levels:

Choose the model and make, and then you can play a few slider controls to select the level of charge, voltage and current to get an idea of the rate of charge, and the range added per hour, costs etc.

EV Charging Calculator USA: Time, Rate, Cost | Green Cars Compare

Estimate charging time, rate, and cost for any electric car in the USA. AC & DC charging. Green Cars Compare Charging Calculator. Free to use

evcompare.io

Ideally, you keep the EV battery as close to 50% charge as practical for your commuting needs. I only charge to 100% for trips out to camp, and normally just charge to 70-80%. Winter (with temps dropping to -25 C) requires 35-40% more time charging vs summer where we only charge for a 2-3 hours every few days. Even with a heat pump, energy use required for heating as temps drop to the more extreme lows can exceed 4000 watts, less if you precondition. I know this wiring is not for you...just providing some information that may help with actual need with respect to EV charging etc.

 

[mike93lx]

Your charging speed may be limited by the vehicle as well. My folks have a Kona that I believe is capped ay 7.2kWh, so going beyond 32a won't have a benefit

 

[Denwood]

Your charging speed may be limited by the vehicle as well. My folks have a Kona that I believe is capped ay 7.2kWh, so going beyond 32a won't have a benefit

Yes, the onboard AC-DC inverter and battery management system (BMS) will limit the charge rate on all EVs. KIA and Hyundai are moving to 800 volt packs specifically to increase this rate, so their vehicle charge limits on AC will be higher, approx 11 kW. That's about 46 amps@240V I suspect the industry will follow.

However, for folks wondering about power needs, the bigger question is your expected daily use with respect to mileage. If you can cover that overnight, then you may only need a small fraction of the max power. Again, if you are using up 300-400 watts in system overhead, then you'll "waste" 3.6 kWh in overhead charging for 12 hours, vs 1.8 kWh overhead, charging for six. This is where that EV charge modelling site is pretty handy It also factors in the different EV efficiency levels. You'll find a Tesla model 3 for example will pick up as much as 50% more range vs other EV models (cars and small SUVs) for a given charge input. Their drive train/aero is that much more efficient.

EV Charging Calculator USA: Time, Rate, Cost | Green Cars Compare

Estimate charging time, rate, and cost for any electric car in the USA. AC & DC charging. Green Cars Compare Charging Calculator. Free to use

evcompare.io

 

[beemerphile]

...KIA and Hyundai are moving to 800 volt packs specifically to increase this rate, so their vehicle charge limits on AC will be higher, approx 11 kW. That's about 46 amps@240V I suspect the industry will follow.

My Model Y with a 400v pack can charge at 11.5 kW on the Tesla Wall Charger. I think the advantage of the 800v pack only comes into play on 800v capable DC Fast Chargers (which are currently pretty rare). I would think that Tesla should be working on that, but I make no claims of being as bright as Elon. They are only looking at it now for the trucks.

 

[TT_Vert]

Thanks for all the info guys. I just looked up the village code requirements for electrical codes and found this. Now I need to research more to see if EMT is actually a requirement. Any suggestions how I can source the info online for EMT requirements for NEC 2005? I will probably have to contact the code enforcement dept. for info on the amendments I assume.

• 2006 - ICC Electrical Code (Administrative Provisions)
• 2005 - National Electrical Code with Amendments

 

[beemerphile]

Thanks for all the info guys. I just looked up the village code requirements for electrical codes and found this. Now I need to research more to see if EMT is actually a requirement. Any suggestions how I can source the info online for EMT requirements for NEC 2005? I will probably have to contact the code enforcement dept. for info on the amendments I assume.

Not likely still running on the 2005. A short search found this...

• (Ord. No. 2021-O-27, passed 12-21-2021)
• Sec. 150.09. - Amendments to Electrical Code.
  SHARE LINK TO SECTIONPRINT SECTIONDOWNLOAD (DOCX) OF SECTIONSEMAIL SECTION
  The following provisions shall further apply and shall supersede any and all references listed within the adopted Edition of the National Electrical Code (NEC) - 2017 Edition - N.F.P.A. 70.
  Additions, Insertions and Changes:
  (a)
  Article 394 - "Concealed knob-and-tube wiring" shall be deleted and prohibited.
  (b)
  Adopt Informative Annexes:
  A - Product Safety Standards:
  B - Application Information for Ampacity Calculation;
  C - Conduit and Tubing Fill Tables for Conductors and Fixture Wires of the Same Size;
  D - Informative Examples;
  I - Recommended Torque Tables from UL Standard 486A-B
  (c)
  The following provisions supersede the adopted codes for all construction including but not limited to: residential, commercial, single family and multiple family buildings.
  1.
  All new services shall meet Commonwealth Edison service and meter guidelines, latest published edition.

 

[TT_Vert]

Not likely still running on the 2005. A short search found this...

• (Ord. No. 2021-O-27, passed 12-21-2021)
• Sec. 150.09. - Amendments to Electrical Code.
  SHARE LINK TO SECTIONPRINT SECTIONDOWNLOAD (DOCX) OF SECTIONSEMAIL SECTION
  The following provisions shall furt

• 
  (c)
  The following provisions supersede the adopted codes for all construction including but not limited to: residential, commercial, single family and multiple family buildings.
  1.
  All new services shall meet Commonwealth Edison service and meter guidelines, latest published edition.

This is what I did find on the city site:

 

[beemerphile]

I had you at Wauconda not East Dundee per your profile info. Still hard to believe 2005.

looks to be correct though

the amendments are listed in the link I gave above at...

§ 151.011 ADDITIONS, INSERTIONS, DELETIONS, AND CHANGES TO THE NATIONAL ELECTRICAL CODE.

 

[mike93lx]

This is what I did find on the city site:

2005 is wild.

 

[TT_Vert]

I had you at Wauconda not East Dundee per your profile info. Still hard to believe 2005.

Yeah this is for my sister in law. Just trying to get info to figure out the best way to allow her future expansion since she's going to be running a new circuit for this. I just called and they are in fact still using the 2005 version of NEC but he did say they require EMT. There are some additions that I need to go through. Particularly 151.011 and maybe 151.018

Dave

 

[TT_Vert]

I had you at Wauconda not East Dundee per your profile info. Still hard to believe 2005.

looks to be correct though

the amendments are listed in the link I gave above at...

§ 151.011 ADDITIONS, INSERTIONS, DELETIONS, AND CHANGES TO THE NATIONAL ELECTRICAL CODE.

Yeah I was looking at those myself. Trying to see where it specifies rigid conduit is required though. And in reading this it appears we cannot even use AL
Found it:

No Aluminum conductors either

 

[beemerphile]

Yeah I was looking at those myself. Trying to see where it specifies rigid conduit is required though.

Search the 28 instances of the word "conduit" in 151.011 and you will find this reference to EMT...

(2) Old work.

(a) New installations of one or more concealed extensions and/or additional outlets or open construction due to remodeling or repair in single- or two-family dwellings shall be in rigid conduit, electrical metallic tubing or flexible metal conduit and shall be bonded to the ground. One or more concealed extensions, in more than a two-family dwelling shall be minimum one-half inch electrical trade size raceway.

 

[beemerphile]

Yeah I was looking at those myself. Trying to see where it specifies rigid conduit is required though. And in reading this it appears we cannot even use AL

Rigid conduit and EMT are not the same thing. Apparently true regarding aluminum. Nationally, aluminum conductors are only prohibited in branch circuits.

 

[Denwood]

My Model Y with a 400v pack can charge at 11.5 kW on the Tesla Wall Charger. I think the advantage of the 800v pack only comes into play on 800v capable DC Fast Chargers (which are currently pretty rare). I would think that Tesla should be working on that, but I make no claims of being as bright as Elon. They are only looking at it now for the trucks.

Tesla has higher charge rates at 400V due to lower resistance cell design and good thermal management, but you are right in that going to 800 volt ultimately allows you to charge at a higher rate given lower current and therefore less heat.

 

[TT_Vert]

Rigid conduit and EMT are not the same thing. Apparently true regarding aluminum. Nationally, aluminum conductors are only prohibited in branch circuits.

From my interpretation I can use NO AL conductor anywhere in there, I assume you interpret it the same way? I had just searched for rigid as I could not query EMT (They spelled it out). As far as flexible conduit goes I wonder if they have the same limitation of a 6' whip liek they do in Chicago. If not, perhaps flexible conduit could be used.

Dave

 

[mike93lx]

From my interpretation I can use NO AL conductor anywhere in there, I assume you interpret it the same way? I had just searched for rigid as I could not query EMT (They spelled it out). As far as flexible conduit goes I wonder if they have the same limitation of a 6' whip liek they do in Chicago. If not, perhaps flexible conduit could be used.

Dave

The No AL thing seems pretty clear unless there is context/an exception that you cropped out.

Copper thhn/thwn it is

 

[TT_Vert]

The No AL thing seems pretty clear unless there is context/an exception that you cropped out.

Copper thhn/thwn it is

Unfortunately not, this is the entire O subsection (Conductors)

 

[beemerphile]

From my interpretation I can use NO AL conductor anywhere in there, I assume you interpret it the same way?

I do. That is a great waste of resources, because there are many benefits to aluminum feeders.

I had just searched for rigid as I could not query EMT (They spelled it out). As far as flexible conduit goes I wonder if they have the same limitation of a 6' whip liek they do in Chicago. If not, perhaps flexible conduit could be used.

Flexible metal conduit (FMC) also called "Greenfield" is different than the liquidite used in outdoor whips. I don't have any local experience and shouldn't pretend to know if they limit the length of FMC. Your code amendments are full of crazy **** so you can't use reason to figure it out.

 

[TT_Vert]

I do. That is a great waste of resources, because there are many benefits to aluminum feeders.


Flexible metal conduit (FMC) also called "Greenfield" is different than the liquidite used in outdoor whips. I don't have any local experience and shouldn't pretend to know if they limit the length of FMC. Your code amendments are full of crazy **** so you can't use reason to figure it out.

Yeah i'm reading through it all now to see if there is mention of limitation on FMC length. Do you know of a legal way to make a tight 90 w/ FMC? Sort of like a pull elbow or an LB? This run will go through a wall and 90 up to more than likely a sub panel.
Maybe FMC to an EMT stub to an LB?

 

[beemerphile]

Yeah i'm reading through it all now to see if there is mention of limitation on FMC length. Do you know of a legal way to make a tight 90 w/ FMC? Sort of like a pull elbow or an LB? This run will go through a wall and 90 up to more than likely a sub panel.

You don't want to bend it enough to kink it or you create a short circuit potential. The minimum bending radius should be specified by the supplier based on conduit diameter.

 

[TT_Vert]

You don't want to bend it enough to kink it or you create a short circuit potential. The minimum bending radius should be specified by the supplier based on conduit diameter.

Right which is why i mentioned going from FMC to an LB. There will be no bending at all then as the short end of the LB will be parallel w/ the FMC feed from the main panel. I am just looking to see if that is w/in NEC guidelines and is an SOP for something of this sort.

Dave

 

[beemerphile]

Right which is why i mentioned going from FMC to an LB. There will be no bending at all then as the short end of the LB will be parallel w/ the FMC feed from the main panel. I am just looking to see if that is w/in NEC guidelines and is an SOP for something of this sort.

Dave

Transitioning from another type of conduit to FMC is widely done. I'm getting gun shy commenting on what might be legal in the lovely village of East Dundee. Better find a local.

 

[dcg9381]

Ahh, wasn't aware the car did all charge control. Why are these chargers so expensive then??

Dave

The car does all the charge control between the EVSE and the charge, but not all cars have configurable controls on the car side. Tesla's can set the charge rate on the car, so you're all good. Buy a Ford E-transit and the car will can set the charge rate up to whatever is allowed by the EVSE. You need a configurable EVSE to use it in multiple places across different breakers. Not unusual in the EVSE space either, but the last one I bought had two options: 40A or 50A. We need more control than that.

They have software to manage the connection, there is hardware involved, and because they can. Broadly, Ev's are still toys of the wealthy. The cars come with plugs that mean a EVSE is not required. It's a convenience and a luxury

The Ford e-transit comes with an EVSE, no straight plug in. Factory options on the EVSE give you two plug types and two charge rate options 120V @ 15A and 240V @40A. Way easier with a Tesla.

 

[TT_Vert]

Thank you all for the input/expertise. It's been eye opening to say the least! I appreciate you taking the time to answer my questions.

Transitioning from another type of conduit to FMC is widely done. I'm getting gun shy commenting on what might be legal in the lovely village of East Dundee. Better find a local.

I will call code enforcement to be certain but I'm just trying to do as much legwork as I can before getting a contractor involved.

The car does all the charge control between the EVSE and the charge, but not all cars have configurable controls on the car side. Tesla's can set the charge rate on the car, so you're all good. Buy a Ford E-transit and the car will can set the charge rate up to whatever is allowed by the EVSE. You need a configurable EVSE to use it in multiple places across different breakers. Not unusual in the EVSE space either, but the last one I bought had two options: 40A or 50A. We need more control than that.

Thank you.