January 2017 Jeff Miller Charging Infrastructure Presentation

[jeffrey.miller]

I am going to post the presentation in text in here so it is searchable by future people (like me).


This is the first of what is likely to be many presentations on the topic of the serious charging infrastructure build I am doing at my house. 

Six steps

Plan
Acquire materials (at a discount)
Upgrade house service to 400 A (320 A cont.)
Install conduit to garage and panels
Install conduit and disconnects for stations
Build and install stations

Continuous vs rated, rated*.8=continuous=charging rate



Power Needs

I would like to charge 2 Tesla’s 75A and 2 cars 35A

• Off peak and as fast as possible (real time pricing)
  Chargers are more efficient at full power
  Cheap rates only last so long each night
  Four family members, and friends who drive EV’s
  Three car garage and one outside at the end of the garage

Considering Electrically heated driveway

• 150+ amps at 240V
  Puts demand way beyond existing 200A service
  Cheaper to put in stuff now compared to rebuilding later
  Can use the power to charge cars when it isn’t snowing

Requirements
75+75+35+35 =220 amps continuous!
I would like to just park where convenient
All chargers the same 75 amp capability
This makes electrician head’s explode
They do load calculations and assume
All 4 100 A circuits are in use 100% continuous
80 A cont *4 =320A = the complete service of the house!
House also has E-Oven and E-AC, everything else big is NatGas
While I won’t have four Tesla’s all charging normally
I need to prevent bad things, and convince inspector all is well


There need to be limits

• Charging stations can be set manually
  Disconnects can have smaller fuses
  JuiceBox and new Tesla charging stations can agree on a current that doesn’t break things (inside brand only)
  Not perfect, as they can’t account for other large loads
  like a heated driveway
  Scouring the internet I have found enough to make me believe I can get a system working with OpenEVSE
  That is another presentation…
  Just set them all to 50A while I work out the details

How am I going to do this?

• Breaker boxes above 225A that work for home service don’t seem to exist
  Normal implementation is to put in 400A meter and then run 2  200A main breaker panels from it.
  My service is on the other end of the house in the basement
  Put second panel in garage direct from meter?
  Put in a meter box with breakers?
  Put another meter on the garage itself?

Service upgrade time!

• In my case I am adding a second 200 A panel just like the existing one in my basement and using a plain meter base without breakers
  This requires the main breakers be very close to the meter
  I also plan to move the E-Oven to the new panel to balance the load when AC and oven are on.
  Only one problem, how I am going to run all of those charging stations when I have my service split in two halves which are in the basement?

• Plural sub panels
  Two of them, one off of each main panel in the basement to the garage. 
  Gain access to more power than a single 200A panel could provide, so long as I can convince inspectors
  I have 150, 125 and 100 amp breakers to run to the subs, and will run the biggest I can get approved.
  The sub panels are 225A capable 42 slot monsters
  The slots aren’t required, but space to turn the big wire for the charging is very nice (they were cheap too)

• Someone in the audience has just realized:
  My job of balancing load across charging stations has just gotten harder 
  I lose the ability to truly park anything anywhere
  However:
  I add enough total power that I am not losing sleep
  Originally the best I could hope for was 100A continuous shared across four stations
  Now I am looking at 240A continuous, with each pair of charging stations sharing 120A continuous
  Two Tesla’s on one sub panel would limit them to 60A each, not ideal, but not worth chasing
  

Charging station connectivity

• With OpenEVSE I can connect conduit many ways and with large wire size, but what if I need to change a charging stations in five years?
  So instead of wiring from the breaker to the charging station I decided to put in a disconnect
  There are more than a few places that this is a requirement
  This will be right at the charging station and for added safety I bought fused disconnects
  I can run any size charging station by changing the fuses
  Proper fuses are more likely to break DC than an AC circuit breaker, they are also faster
  Could DC back feed in to the charging station?

In theory if the charger in the car breaks in just the wrong way it could connect the DC battery pack directly the 100 Amp AC circuit feeding the charging station.  Depending on the relative voltage and exactly how it went wrong we are either going to be backfeeding DC in to the grid, or doing some very quick charge, discharge cycles to the battery pack.  These are both bad, backfeeding DC in to the grid could damage many things in the rest of my house, and since circuit breakers are designed to break AC current only it is likely that it will try to open, only to be fused shut / catch fire by the high current DC voltage flowing through it.  This will result in further damage.  The resistance of the grid is possibly enough to keep the EV fuses intact as they can provide lots of amps for the car to drive.  It is possible that the fuse for charging is different than the controller, we hope so in this situation.  Putting fast blow high DC current breaking fuses in line offers additional protection to my house, car, and family.  Possibly the reputation of EV's across the world.  Before you say that could never happen, lightning strikes routinely cause exactly these types of scenarios in computer power supplies.  I also had a car battery charger that died just like this during a storm.  When I took it apart the transistor was shorted through, and the 1 amp fuse was predictably blown.  Scaling up for a standard 12V car battery to a traction battery, and the circuit breaker is the only external protection as most installations.  I will be putting surge protection in the breaker boxes, but they are no guarantee, and since they are parallel, not in line with the car, they can't even blow open to prevent a surge. 
Maybe I am paranoid, but compared to the money spent of the rest of this stuff this has the best chance of stopping anything truly bad from happening for a reasonable cost.



Materials
Wire sizing
Determining wire gauge is easy, except it isn’t really. 
I have bought for 150A, and 100A connections
Wire insulation is THHN which is 90C rated
https://lugsdirect.com/WireCurrentAmpacitiesNEC-Table-301-16.htm
So can I carry 150A on #1?  The NEC310.15(B)(16) table says I can
No, the breakers only allow 75C load rating, and requires a minimum of 75C rated wire
http://www2.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/content/live/FAQS/175000/FA175147/en_US/Wire%20Terminations%200110DB9901R2-02.pdf
So why is THHN the most readily available? 
Temperature Derating, my garage is above the ambient temp which is allowed to run 75C wire at full rated current

What I need wire
1/0 copper THHN for 150A breaker to subpanel 300 ft
#6 bare copper earth ground main to sub run 100 ft
#3 copper THHN for 100A breaker to disconnect 450 ft
#8 bare copper earth ground from sub to disconnect 150 ft
I also got a deal on some #4 copper so I picked that up to cover the ground to the mains and the ground rod for the main panel upgrade 25 ft
I could use the #4 to run to 50A outlets if I want
Ft lengths are what I calculated I needed


Conduit

Now that we know what wire is going where, we  can calculate the conduit size.
  http://conduitfillcalculator.com/
They don’t include bare wire for ground, so I have used to THHN to estimate that.
For runs with 3 or more wires, you have to be below 40%. 
I am using Electrical Metal Tubing (EMT) as it is thinner and lighter than Rigid Metal Conduit (RMC)
By picking 3 #3 and 1 #8, we get 38% fill on 1 inch EMT
By picking 3 1/0 and 1 #6, we get 29% fill on 1.5 inch EMT
Dropping to 1.25 inch EMT yields 40.5% fill
The runs from the basement to the garage will be challenging enough to pull the wire through that I don’t want to make it harder by trying to go with a borderline fill ratio
There are adjustments that can be made for the total amount of bends in a run of conduit
No more than 360 degrees of bends in any one cable pull.  You can insert a pull box to break the pull in more than one part.
My basement to garage run will have about 300 degrees of bends, so having a 29% fill will help make that pull much easier
The sub panel to disconnect pulls will only have about 200 degrees so higher fill worries me less


What I bought
4 100A 240V 1ph 3wire fused safety disconnects, I chose SquareD D223N, D223NRB for outdoor
2 150A+ 240V 1ph 3wire main lug breaker boxes, I chose the 225A SquareD 42 slot as they were cheaper than anything else I found
Additional main panel 200A 240V 1ph 3wire, I chose a matching one with what I already have
Meter base 400A 240V 1ph 3wire, 2 sets of lugs, I chose Milbank U1748-O for underground wire
Comed has an approved meter base list, this is one of the few 400A on it, and it seems to be the most common
I kept the same brand and type of breaker boxes so that I could move breakers around at will
SquareD QO series in my case, and they are readily available at more than your local store
Nothing better than retail on Craigslist after monitoring for 6 months
Bought them on Ebay for deep discounts compared to other sources
QO are going through a product changeover which the old models are phasing out, but the feature they added doesn’t matter for my purpose
I paid 89 for the 225A and 95 for the 200A panels
Free shipping

I spent 6 months monitoring Craigslist, ebay and Amazon for SquareD QO breakers 100A and above. 
100A breakers 2 pole, $31 avg cost delivered
125A breakers 2 pole, $26 avg cost delivered
150A breakers 2 pole, $175 avg cost delivered
200A Main breaker, $45 delivered
The 150A breakers are much more expensive and they also consume four slots in the box instead of two

I went for the SquareD D223N (3) indoor and D223NRB (1) outdoor
Nothing good local for 3 months on Craigslist
Ebay yielded results on New or close enough to new units to meet my needs,
To my door costs 151.57 for all 3 D223N, and 65.24 for the D223NRB

300ft of 1/0 THHN craigslist $205
1000ft of #3 THHN craigslist $400
250ft of #6 ground craigslist $80
500ft of #8 ground craigslist $100
161ft of #4 THHN craigslist $45
$830 in copper cable!
I have serious excess in #3/8 which will get resold
Retail for that is about $1600, and that is shopping around for it.   







Thoughts on Juicebox

I was talking to JuiceBox and their 75A charging station has a 6 gauge whip to connect to the service provided by a 100A breaker.
They were quite confident in their solution and suggested using a junction box to connect to larger wire.
You can’t wire it direct to a breaker, or even a service disconnect (which was my plan) as breakers and service disconnects are only rated for 75 C wire, and this would be 90C+ to run 100A service through a #6 wire. 
I wasn’t impressed as their documentation didn’t point out this detail or reinforce the junction box suggestion as the requirement that it is. 
An electrician should know this but why take that chance.


I reorganized this content compared to my presentation order, and added some written notes to fill in for my verbal stuff.  Feel free to ask questions.

[jeffrey.miller]

Conduit size links
https://sizes.com/materials/conduit_EMT.htm
http://www.home4c.com/conduit.htm

Milbank 400 A meter box
https://www.gordonelectricsupply.com/index~path~product~part~35522~ds~mfr~process~search~qdx~0~ID~%2CMilbank%2CMeter.Sockets...Com.Ed
https://images.tradeservice.com/9ETBOIYK8205G6UU/ATTACHMENTS/DIR100131/MILBANE05090_1_2.pdf


Someone asked about AFCI GFCI protection
http://www.homedepot.com/p/Leviton-20-Amp-125-Volt-AFCI-GFCI-Dual-Function-Outlet-White-002-AGTR2-00W/300049855
http://www.homedepot.com/p/Leviton-15-Amp-125-Volt-AFCI-GFCI-Dual-Function-Outlet-White-R02-AGTR1-0KW/206804820
You can also get that same protection in a Circuit breaker.

[jeffrey.miller]

If you ever wondered what the number "10K" or "22K" means on your circuit break this forum page seems to answer that question quite well

http://forums.mikeholt.com/showthread.php?t=56030

Post #6 by friebel
"
To: mgnh, I would recommend that you contact the Cooper Bussman Company to get their book on "SPD Selecting Protective Devices, Based on The 2002 NEC. Their phone number is 636-394-2877. They will send one to you free of charge. If you were close by I have several in my possession.
This book will explain all that you would ever want to know about AIC, and Selective Fuse Co-ordination.
Now to answer your question, "What does AIC mean?"
If you took a bar and shorted out the secondary of the transformer that feeds your facility, that would be determined to be the Available Fault Current. Suppose that this current would be 50,000 amperes. Any fuse down stream of that fault would have to have an interrupting rating of at least 50,000 amperes.
Today, if you would look on the barrel of the fuse, you would find a rating saying 200ka or 300ka. Meaning 200,000 or 300,000 amperes.
Now, as you go further downstream from the 50,000 amp fault, the fault current will decrease because of the resistance of the wiring in the circuit. For example, generally at a lighting panel, the circuit breakers are in the range of 5000 AIC or 10,000 AIC.
But bottom-line, get the book that I suggested, and it will answer all of your questions.
"

As another poster on that forum notes, it is often referred to AIR not AIC on some breakers.  

Passing 22,000 amps through a 10K breaker is likely to result in a fire or small explosion, just like trying to break 400 volts DC with a 48 volt rated fuse! 

At my house my main breaker is a "22k" but all of the other breakers in my panel are "10k" because the wire size has high enough resistance to prevent more than 10,000 amps from passing through them.  I would guess that few people would bother trying to locate higher rated breakers but me being me, most the breakers I have purchased are 22K breakers.  I got them for little to no premium over the 10K breakers so I got the better ones.  Are they required?  For the breakers heading to the subpanels this could be a legitimate concern, the wire is very large and low resistance.  For the #3 wire heading to the charging station, this is a bit less of a concern, but the price was right, so those breakers are protected against catastrophic failure in the case of a low resistance short.  So for me if the price is equivalent get the better breaker    

[simon.gibson]

A gentleman from ABB gave us a presentation on how the spark inside a breaker is quenched...
Also note that breakers are rated for branch circuit protection or supplementary protection. UL Added this in 2005:
http://www.ul.com/wp-content/uploads/2014/04/ul_OvercurrentProtectionSupplementary.pdf
Branch Circuit UL 489 - Protects wire and cable against Overload and Short Circuit
or
Supplementary UL1077 - Provides additional equipment protection where branch circuit protection is already provided or not required AND Not suitable for the protection of branch circuit conductors

You'd be surprised how often the supplementary is (mis)used!!!
This might make useful reading although Mike Holt is the 'go to'
http://library.automationdirect.com/branch-vs-supplementary-circuit-protection/
 

[jeffrey.miller]

The electrician hasn't been able to come out and do the service upgrade yet.   

I have been tempted on several occasions to do it myself, but I have shown restraint. 

What I am trying to avoid is running the conduit for the farther charging stations in the summer time.  I have to run them through the garage attic, which is confined, south facing, and red brick, in the summer.  Since that is one of the last steps of this project I was hoping to get started about the new year so I could be running that conduit in March, before it gets hot up there.  Best laid plans and all that.

On the downside, I was talking to member Mark about his Leaf, and he mentioned all of this charging stuff netted him a nice rebate, but that program is over.  Since one of the stipulations was you had to use an external electrician I would have paid more, but got some back, not sure I would come out ahead though. 

[bob.baker]

Jeff can u call my Shop    847-842-9543

[jeffrey.miller]

The electrician has me on his calendar for April 8th for the service upgrade. 

[jeffrey.miller]

The electrician didn't want to get permits for the work and decided not to do the job.  I do want permits pulled for a service upgrade, it isn't an easy undo and disabling it kills power to the house making the family unhappy. 

Back to shopping for electricians. 

[jeffrey.miller]

I have located an electrician for the service upgrade.  His company frequently does service upgrades and he brings out three people to run through everything in one day.  I don't have a date yet, but assuming obtaining the permit doesn't take forever, it will be in the month of May. 

I met with another electrician that I will probably work with on future phases of this, but as he works alone he couldn't get through the job in a single day.  He was willing to put temp power in place but the process was going to take longer and potentially cost as much if not more money.  He also doesn't do as many in a year as the bigger company, so I get the benefit of that experience. 

On the Comed front of the in ground wire, I called their 800 number and asked what would be required from ComEd to get this service upgrade going cost wise.  The agent opened a case with the Crystal Lake city ComEd rep.  That rep called me a couple of hours later and told me the wire in the ground was the proper size for 400 already and that they would inspect it once the city had completed their inspection.  Comed would then send a tech out to replace the meter.  According to the Comed person the meter itself wouldn't fit in the new base properly. 

No electrician I have spoken to expects that to be a problem, but they have a hard time mentioning recent jobs specifically upgrading 200 to 400.  Such is life as an early adopter. 

I will provide more details about the job and the contractor once the job in complete. 


The most amusing discussions have come from the 150 Amp breakers and the fact that not only do they exist, that I have two of them in my possession.  If you recall they are MUCH larger than a normal 2 pole breaker and the shock and then amusement when these guys hold these massive things for the first time is quite hilarious. 

[jeffrey.miller]

Another detail that has come from my discussions around this is that the local inspector matters.  Every town has their own inspector and those people have differing opinions on topics.  Speaking to the inspector before a big job like this is certainly a good idea as there are details that are smaller than what is covered in any code book.  This can cause rework on jobs because the inspector doesn't like how it has been done.  One of the factors in me selecting the larger group was that he does this same job in many towns and he takes the most stringent requirements from each of the towns and applies it to every service upgrade.  This limits the chances for rework and helps him be more successful.  These are often very small details down to choosing between two perfectly acceptable fittings. 

Getting buy in from the local inspector is an important step in any project that you want pass on the first inspection. 

[jeffrey.miller]

I have a building permit for the first phase (upgrade to 400A service) and an electrician scheduled to perform the work Thursday the 11th of May.  They are planning to complete work in a single day with 3 people.  Assuming I have power the night of the 11th I will post if they succeeded. 

[ted.lowe]

Great to hear Jeff.  May the force be removed and returned to you in that single day! 

[jeffrey.miller]

Power is back on, they are tidying up the last of the stuff.   

[jeffrey.miller]

Thanks for the support Friday night everyone.

I will try to post some photos from the upgrade. 

Also noteworthy if I hadn't gotten a permit I would have been left with a 200Amp smart meter, compared to the green 400Amp smart meter that was installed when Comed came out. 

Next stop is making up drawing and plans for the two subpanels. 

[jeffrey.miller]

I just submitted the building permit for the rest of the work.  I decided I would rather have the whole thing reviewed as one massive piece of work, then piecemeal.  What I did do is ask for the disconnects to be considered outlets and have the permitting process stop there.  The goal is what charging station I plug in is up to me to do at my leisure.  I observed that there are no 100 amp outlets and as such this was my best substitute.  Also I noted that I recognized the limitations of the service is lower than the total of the potential demand, and I explained why I wanted that and the various ways I can control it. 

As part of the documentation I measured the current flow through the mains in each panel under a high load condition and I have a pretty good amount of breathing room as my higher leg of the service was drawing 45 amps.  That leaves me at least 35 amps for things that weren't on at that moment in time.  I will probably look through what is connected where and move a couple of breakers around to balance my load a bit more, my red side is pulling double the amps of the black side in both boxes.  Evening that out a bit would be good, but that is analysis for another day. 

On top of the four 100 amp disconnects I also added two 50 amp outlets.  With those in place I would have the ability to charge six cars at an average of 40 amps each.  It would also provide flexibility for various conversion EV's that don't have J1772. 

Now I wait 7 to 10 days for the inspector to respond.