January 2017 Jeff Miller Charging Infrastructure Presentation

[jeffrey.miller]

I am building my own charging stations out of components.  If I skipped the box I would have live wires hanging in free air.  Seems less than ideal   

I would use the OpenEVSE enclosure, but it is to small to assemble an 80 amp charging station into.  I am using their normal electronics with an uprated cable and contactor to handle the higher currents.  Their normal electronics support up to 80 amps in firmware so that isn't an issue. 

https://store.openevse.com/collections/all/components  to check out their component list. 

https://store.openevse.com/collections/openevse/products/openevse-international-combo-openevse-v3
This component kit is almost perfect for me, except it contains the contactor I don't need as I am using the larger one. 

[jeffrey.miller]

Another thing I ran across very recently

https://electrek.co/2018/02/09/ev-charging-credit-extended-2018/

Federal EV charging equipment credit has been retroactively renewed for any equipment brought online in 2017.  If you installed stations last year, you might want to check your taxes.

Form 8911
https://www.irs.gov/pub/irs-pdf/f8911.pdf
Instructions
https://www.irs.gov/pub/irs-pdf/i8911.pdf

30%, max of $1000.  If you have already filed and you put in a bunch of equipment last year it might be worth amending your filings which can be done for many months still. 

[jeffrey.miller]

Work session May 5th 9:00 AM start at 199 Midway Ct Crystal Lake, lunch provided.  If possible, let me know you are coming so I can plan sufficient food.

At this point three of four disconnects are mounted and ready for cable.  I should have the fourth one done by the weekend. 

[ted.lowe]

Hi Jeff,

Thanks, i may be able to attend this work session.  What is the topic/tasks planned?  i'm sorry i missed your talk in the 2nd half of the April meeting where you probably mentioned this.

Thanks,
ted

[jeffrey.miller]

I forgot to mention what we are doing! 

Pulling cable from the subpanels to the disconnects in the garage.  As the subpanels are easily turned off there will be no electrocution danger in this project. 

This involves several work streams that can happen in parallel:
Run a fish tape through the conduit from one end to the other
Mark fish tape for length so we can get the right length wire after we pull it out
Tape rope onto fish tape and pull rope through, also put some lube into conduit
Tie rope down to prevent it falling out 
Roll out fish tape for measuring against actual cable
Unroll actual cable and cut to length
Mark each length of cable a color to denote hot, hot, or neutral by wrapping a few feet of each end with colored electrical tape
Bring cut cables to one end of the rope and attach to the rope
Team of two people start pushing/pulling cable into conduit, also apply some lube to the cable
If it gets difficult, utilize mechanical advantage as required


There are five things to run cable to, two are close by but the other three are long and complicated runs of conduit. 

My goal is to get the cable in place, I have no problem stripping and connecting it all by myself but doing all of the above physical tasks alone takes a long time.   


110 car charging is available for at least two vehicles.  240v J1772 is also available while work is not being performed (this is less than ideal). 

As you can see from the above task list there are many tasks that are easy to run in parallel.  This isn't really possible with running conduit which is very serial by it's nature. 

I look forward to seeing some of you Saturday, please RSVP and include food preferences so I can be properly prepared.

Already planning for Vegan with my standard Vegan Chili and will expand on that as I learn more about who is coming.

Thanks,
Jeff

[michael.willuweit]

Can't wait to help although I'll be a little late as I have a morning obligation until 10:30 in West Chicago

[jeffrey.miller]

We rocked the work on Saturday and pulled all of the cable before lunch!  I was hugely impressed with what we accomplished.  I spent the evening stripping and connecting and finished connecting everything for the left subpanel.  I will work through the right one tomorrow night and hopefully get it done so I can have the inspection late this week. 

Thanks for the help everyone!

[jeffrey.miller]

Inspector should be here in a few minutes.

While reviewing NEC I found the old link to the 2005 code was dead so I found a new one
http://www.northchicago.org/vertical/sites/%7B892BE042-FCA9-4ADD-99D5-E4FC8D1104BD%7D/uploads/2005_National_Electric_Code_(NEC).pdf
Suggest a local copy if you need the 2005 version in case they delete it too.

Will report back with results. 

[jeffrey.miller]

Inspection passed!

They were very happy with my work.

We discussed my next permit, their biggest concern is that it works for the next owner without overloading, I will have to figure out how to make them happy while retaining the flexibility I desire.  I think software could be good enough, but it would be best if it was in the charging station, will have to figure that out.

At the very least I now have two 50 amp outlets I can charge my EV's on, which gets the job done.

[ted.lowe]

Congrats on passing your first inspection Jeff!

i'm not sure what you mean by "overloading".  Drawing too much power from all the charging spots at once?
Isn't that what the circuit breakers are for?

Did you get the next permit yet?  If not, do they need some NEC detail to issue the permit first?  Seems there is some "winging it" going on... this scenario probably hasn't happened too many times on a residence in Crystal Lake or in the whole USA either

[jeffrey.miller]

Article 625 covers charging stations.  A good read for everyone honestly. 

As you likely recall I have two main panels, feeding two subpanels with 120 amps continuous each.  The two charging stations connected to each subpanel are capable of providing 80 amps each which would cause an overload condition of 40 amps above the continuous rating of the circuit powering that panel.  Somehow I have to limit the total current per panel to 120 amps in a way that is robust enough to pass on to the next owner of this house while assuming the next owner doesn't have my level of understanding.  There are several possible approaches, from the easy, just set them all to 60A and forget about it, to the extreme, software based controller that runs the whole house while monitoring the price of power and adjusting demand to minimize cost.   There are a vast number of ways to skin this cat, so I will be figuring out my approach and then writing it up. 

[jeffrey.miller]

As I mentioned in the meeting the other day I am looking for fast blow fuses for the disconnects, and I want the highest DC voltage rating along with the highest DC current interrupt rating (AIC, see many posts ago for that).  First a reference on what the different classifications mean:
https://www.fusesunlimited.com/glossary.aspx

The fuses that came with some of the units were type RK5, which is a slow blow type, good for motors.  I need the opposite, a fast blow to protect the equipment, wire, and possibly my house.  Type RK1 is what is appropriate for my purpose as it is designed to stop current flow, not just sever the connection and hope for the best.  

I also mentioned I expected to pay a bunch of money in fuses.  The ones I had seen previously were over $100 per fuse, and I need 8.  After spending some time digging I have located a fuse model that sells for a fair bit less than the others, at some vendors.  
Ferraz Shawmut A2K100R, also Mersen A2K100R
Unlike the More common Bussman or Littlefuse brands that I can't find for below 100, these seem to retail for under $40 in at least two cases.  
https://www.allfuses.com/a2k100r
https://www.pacificcoastbreaker.com/a2k100r-100a-250v-class-rk1-fast-acting.html

I haven't ordered any yet but will be soon and will update who I went with and if they stole my money or not

There were also some of these for sale on Ebay, but they weren't that much cheaper for something that could be easily counter-fit.  

That fuse is also rated at 250 VDC unlike the Littlefuse version that I had found that was only rated at 125VDC, while costing 1/3rd the money.  


In other somewhat related news re-reading the NEC 625.34 in the 2005 book and noted that when dealing with EVSE greater than 60 amps it's disconnect has to be able to be "locked in the open position", and needs to be "accessible", or close to the charging station.  
"locked open position" means that you can apply a padlock to the disconnect to prevent someone from turning it back on.  This requirement is quite common in industrial settings where equipment maintenance teams can turn off equipment, and lock it, so they can work on it without worrying about someone turning it back on.  This is a feature in the disconnects I have installed.  

[jeffrey.miller]

I didn't answer the overload question thoroughly enough for my liking. 

As discussed above I have two panels that can deliver 120 amps continuous, but they are supplied by 150 amp breakers.  The 80% rule applies to any continuous load like EV charging.  In this case the 150 amp breaker would not trip very quickly at 160 amps, and at 150 amps it should never trip.  150 amps is a 30 amp overload from the continuous rating of the circuit feeding that panel.  It will likely do this for a long time without nuisance tripping, but eventually the breaker will start to overheat and fail.  This is the scenario they are trying to make sure I prevent.  I need to create a way to "set and forget" the charging stations so that they never overload the 120 amp continuous rating of the 150 amp circuit.  There is a bunch of room between 120 and that 150 breaker tripping and they want to make sure that isn't abused. 

I also want to make sure it isn't abused, as it leads to things being potentially unsafe. 

To me the gold standard is to have the charging stations read the total current coming into their box and limit it to 120.  This would require current sensors in the sub panel, a way of sending that current data to each of the EVSE connected to that sub panel, and the EVSE being smart enough to figure out when to reduce and by how much.  This could potentially include the two EVSE that could be plugged into the 50 Amp outlets. 

The above is a very tall order, and it not only has to work while I live here, but forever more!  Forever more implies physical cables with some form of communication running through them to negotiate.  There are no standard in this area.  The closest thing around is the Tesla High Power Wall Connector (their 80 amp EVSE).  Two of those can share a single circuit (according to the install manual) however they aren't set up to share a large service that isn't larger than each of them can deliver.  In other words, you set in the units an amperage of the circuit they are sharing with a max of 100 (80 delivered), however in my case I would need to set them to 150 (120 continuous) but that isn't an option. 

If Tesla provided that ability off the shelf I may have bought them and switched the ends over to J1772.  (there is even a service that does this for a fee)  That doesn't answer my whole laundry list of other things I want to do, but it would be easy to justify to the inspectors. 


Hopefully that clears things up. 

[ted.lowe]

Great explanation, thanks Jeff!  i remain very curious to see what your solution is.

Re: the lockable disconnect

i find that interesting about EVSEs, because the same requirement is in section 690 for solar PV systems.  Within 6' of the ground, on the outside of the building, lockable "off" disconnect.  Maybe for a slightly different reason though, to let utility linemen make sure that a distributed energy generation system is not feeding the lines while they work on them. 

[jeffrey.miller]

I am thinking my solution (temporary) will be to install two big charging stations (I have all the parts to build two) and assume two small ones, and submit that as an initial permit.  That gets me two 80 amp full time and two 40 amp full time stations which is exactly what my limit is.  Once I sort out the controls for the other two I will permit and install them and implement some form of overarching control system to manage all of them. 

In related news, the temp tags arrived for the Tesla today.