TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here: paypal.me/SupportTMC

Incoming utility cable capacity - A cautionary tale

Discussion in 'North America' started by ModelS1079, Jan 8, 2013.

  1. ModelS1079

    ModelS1079 Member

    Joined:
    Jun 23, 2012
    Messages:
    837
    Location:
    Suburban Boston
    #1 ModelS1079, Jan 8, 2013
    Last edited by a moderator: Jan 9, 2013
    Misadventures in Charging-
    Hold - keep this thread. Happened last night. Gotta run but will share the story ASAP. Yes the car is fine. Yes my wife and kids are too!




    [Moderator Note: Inflammatory title edited.]
     
  2. MikeK

    MikeK R#129, TSLA shareholder

    Joined:
    Jun 29, 2012
    Messages:
    1,133
    Location:
    San Francisco Bay Area
    Um. Respectfully, why post this without any detail, even for a short period? A thread title like this is just going to freak people out.
     
  3. ModelS1079

    ModelS1079 Member

    Joined:
    Jun 23, 2012
    Messages:
    837
    Location:
    Suburban Boston
    #3 ModelS1079, Jan 9, 2013
    Last edited: Jan 9, 2013
    My, it sounds like an apology is in order.

    Dear Tesla friends, family, faithful-I am so, so sorry for posting and then running, but life circumstances related to this event took me away from my computer and I am just returning now. With my posting about the explosion, I simply meant to entice your interest, not incite fear. That said, we did have an event, and I am happy to share it.

    Again, those of you who know me from posts over the past many months know that I would never leave you in danger-no! All is fine, and here is what happened.

    1. This is not Tesla's fault. You are not in danger.
    2. All is fine.
    3. Here's what happened:

    Late Monday evening, January 7-actually, it was early Tuesday morning, January 8 at 12:21 AM, I was having trouble sleeping. My eyes were just slightly open, I was exhausted from the usual long day at work. Aren't we all?

    Suddenly I heard - and felt- an explosion immediately followed by a flash, coming from somewhere beyond my window shade: fireworks! That was my first thought. Some kid in neighborhood was lighting off fireworks. "How annoying" I thought. My eyes began to close again, but through the shade I could still see the flickering Of yellow and orange light.

    Now, with increasing trepidation, I got up and looked out the window, pulling back the shade:
    As I looked out the window, bleary-eyed, I could see yellow and orange flames running up the side of my neighbor's house. "Oh my God!", I thought-my neighbor is 87 years old. I've got to get her out of there.

    As my eyes began to focus, I could see that the yellow and orange flames were actually a reflection that I was seeing in my neighbors windows.
    Good news! My neighbor's house was not burning. The flames were coming from my house. How silly of me.

    Within 12 seconds I was at the front door, looking up at the front corner of my house, where 2 to 3 foot flames were flowing up from the front corner. Within another 32 seconds I had called 911, And I had all three children and my wife out in the street, barefoot in pajamas. Little chilly here in the Boston area that evening, I should note.

    As a two fire trucks, two police cars, a truck with a spotlight on it (I want that job), and soon 2 water and sewer trucks, and the local light plant truck and local light plant four-story crane all arrived, the fire burned itself out, and it became more obvious what was happening.

    The actual house never burned. The fire was coming from the corner of the house, on the large wires that enter the house. The flames actual reached a few inches from the house, the actual house itself never actually caught fire. Small detail, but one worth noting.

    The tree above the wires was singed, but never caught fire, there were ashes, soot, melted plastic all over the front yard. The fire burned out before anyone could even roast marshmallows.

    There was also quite a bit of commotion, a lot of lights, and a lot of very dark neighbors' houses, as all the power was out on our street.

    As fireman, policeman, water and sewer (don't even asking why there were there, I'm not sure) and light plant people began to assemble, along with several neighbors - among whom I was hereto forward not that popular - I had this rather uncomfortable feeling in the pit of my stomach that it was not a coincidence that my electrical service was just completed to charge my new electric car, and that all these nice people with well-lit trucks were visiting us at about 12:30 AM.

    As I thought about exactly how this could happen, I was darting my way into the basement to turn off all electrical breakers...then, knowing everyone was safe, I then began to wonder-will the car still be in the garage in one piece, or is the car actually burning at this point? I slowly opened the door- pitch black but no smell of smoke. Tesla Model S visible under the dull light of the cell phone. That blue looks even darker in the dark.

    All good.

    I really wanted to stay right there, where it was quiet, dark, free of my rather frantic neighbors, and most of the people our town employs to keep us safe, all of whom were awaiting my return to the street.

    But I pulled myself together and walked back outside. Soon, the fire department cleared the house as "safe", walking through the house with flashlights. As I explained that I had an electric car, they asked me what type, I told them it was a Tesla, and then, in the dark of the house, with my family standing in the driveway barefoot, freezing, they asked if it would be okay to "go see the car?". I kid you not. An unusual showing of the car, but we do whatever is required for Tesla, right? I reminded them that my family was turning into ice cubes at this point, and after a brief flashlight-guided tour of the car ("wow, that is so beautiful, what a car"), we headed back outside together, and the family was allowed to reenter the house.

    We had been outside for just about an hour.

    Best line of the night: as my daughter turned to walk inside, just absolutely frozen, miserable, a little after 1:30 in the morning, she turned to me and with a wry smile she said, "Hey Dad-really great car."

    So, then it became a major project to be sure we understood what happened. I have a special type of electric heat called electrothermal storage. It draws over 200 A at night in order to heat a big "refrigerator" of bricks, which is then used to heat the house during peak hours in the daytime. It's a quiet, carbon dioxide-free, inexpensive, and presumably safe way to heat a house. However, when the electric car was added to the same circuit, the wires (these are not wires, they are cables) that go from the telephone pole to the house were not adequate for this load.

    By 330 or 4 AM our electricity was back on, that heat was working, and the car was charging. Amazing. That four-story crane reached across the 52 feet from the house to the street, three guys climbed up on ladders, replaced all the wires that night, in the dark. They also restored power to all the neighbors.

    It was the next day, after the light plant held an emergency meeting, that they realized for sure that the wires were not prepared to carry the load that was given to them. They came back to the house and replaced all the wires up and down the street, with special attention to putting in special, heavy-duty cables from the telephone pole to the house, which will be carrying (and are now carrying, at the time that I write right now) the 200 amp service for heat, plus the 40 A for our Model S.

    I have had the heat for a couple of years, and never had a problem. It was when the town added the car charging to the same circuit that this problem occurred. The plastic insulation on these very large cables simply melted, the two wires which touched each other, causing a large explosion, fire, and-ultimately, a posting on the Tesla form which I regret was not followed-up as it should have been-my fault, obviously.

    The next day was spent getting the front yard/side of the house/plans for replacement of all the wires in the area all in place. In all truth, I played hockey at 6 o'clock that morning and worked a full day in till 7 PM as well, so a lot of this was done after I got home last night, and I simply did not have time and forgot to post. Whoops.

    If there is a lesson that is meant to be shared more broadly with all, it would be to simply be absolutely sure not only that your electrician has provided the proper service for your house, but that the town has provided the proper wiring for the service.

    That said, it seems unlikely that virtually anyone else would have both electrothermal storage and an electric car. Would love to hear from you if you do.

    The reason these are both on the same circuit is because we have a special off-peak rate in town, 5.5 cents per kilowatt hour. I have service coming to the house specifically for off-peak usage, that splits into 2 meters-one for heat, and one for charging the Tesla.

    So, now I have to ask-what will happen when I add a second electric car to the circuit? Perhaps I'll be roasting marshmallows on the front lawn with my neighbors. I'll be sure to keep you all posted. Fully posted that is, with all the potential intrigue, and none of the potential incitement.

    Onwards, With your forgiveness, please.
     
  4. dsm363

    dsm363 Roadster + Sig Model S

    Joined:
    May 17, 2009
    Messages:
    18,235
    Location:
    Las Vegas, NV
    No problem. Thanks for getting back with us and glad you and everyone are ok...and the Model S is ok too:smile:

    Are they going to upgrade the service to your house from 200A or is that even possible?
     
  5. drees

    drees Active Member

    Joined:
    Jun 23, 2009
    Messages:
    1,121
    Location:
    San Diego
    Great story and glad that all has ended well, since it easily could have ended with significant damage.

    Just a question - I presume your heater and charge plug was permitted and installed by a qualified electrician not to mention a large service panel capable of handling the load - I wonder who dropped the ball in checking that the service wires weren't capable of handling the load? You must have 300-400A service running to your house - shouldn't the supply wires be capable of handling 300-400A without burning up?

    Here's a quick tip to check for potential issues in your wiring while charging with your Tesla:

    The Model S displays the line-voltage while charging. By using your Model S as a volt meter while charging you can look for significant voltage drops under load. Ramp down the current as low as it goes and record the voltage. Ramp it up in a few steps up to maximum current while recording the drop in voltage (you will almost certainly see a bit of a drop unless you are plugged in very close to your service panel). Multiply the voltage drop by current and know you know how much energy is being absorbed by the wiring leading up to your car. If you see much more than a 5% drop (12V assuming 240V charging) in voltage, you probably ought to check things out further. Repeat this with other big loads running (air-conditioning/heat-pump other electric heating laundry or cooking appliances for example) for further checks.
     
  6. Doug_G

    Doug_G Lead Moderator

    Joined:
    Apr 2, 2010
    Messages:
    15,848
    Location:
    Ottawa, Canada
    Wow, that sounds spectacular and scary. Someone really dropped the ball on the electrical load calculations, though. That never should have happened.

    I've never heard of a heating system like that. Very interesting, and a cool use for nighttime base load!
     
  7. ModelX

    ModelX Member

    Joined:
    Aug 24, 2012
    Messages:
    918
    Location:
    Orem, Utah
    Amazing story! Glad all (family, house and car) are all ok! I enjoy the way that you tell the experience!
     
  8. Discoducky

    Discoducky Active Member

    Joined:
    Dec 25, 2011
    Messages:
    2,883
    Location:
    Seattle
    Respectfully, this has nothing to do with Model S and should be in the "Electricity" sub-section or equivalent. Great cautionary tale though!
     
  9. mulder1231

    mulder1231 Active Member

    Joined:
    Jan 1, 2012
    Messages:
    1,041
    Location:
    Menlo Park, CA
    How many hours do you need to draw the 200 Amp for the heater? It seems the delayed charging app from Tesla could help out here..
     
  10. efusco

    efusco Moderator - Model S & X forums

    Joined:
    Mar 29, 2009
    Messages:
    4,585
    Location:
    Nixa, Missouri, United States
    Thanks for finally getting back to us on this. Very glad that you, your family and home (and the Tesla) are all safe and undamaged.
    I hope that FlasherZ chimes in, I'd love to hear his perspective on the inadequate wiring. Isn't that something the installer should have noticed before hand? How did it pass inspection without someone noticing? Really pretty scary that a mistake like that could slip by b/c the outcome here could have been very much different and you and I as lay people would never know what wire is appropriate or not.
     
  11. rolosrevenge

    rolosrevenge Dr. EVS

    Joined:
    Feb 7, 2009
    Messages:
    1,851
    Location:
    Right behind you...
    Wow, 200A at night, that's not an average load at all. Thanks for posting it. Do you mind if I pass it around my office, since we are building software for the utilities specifically to avoid these problems.
     
  12. doug

    doug Administrator / Head Moderator

    Joined:
    Nov 28, 2006
    Messages:
    15,912
    Location:
    Stanford, California
    Definitely a useful and entertaining story.

    tl;dr: In addition to your in-house wiring, be sure that the city/town wiring to your house is up to stuff, especially if you're using a 200 A electric heater while trying to charge your car.
     
  13. Vger

    Vger Active Member

    Joined:
    Apr 10, 2009
    Messages:
    1,682
    Location:
    Salt Spring Island, BC, Canada
    Wow, what a tale!

    Excellent point to bring up in this context!

    The model S (and Roadster) actually measure the impedance of the source circuit used to charge the car. The car will throw a warning to the dash, and record the event in the vehicle log, if the voltage drop is too great. It does NOT reduce the charge current or interrupt the charge however! You are responsible for taking stock of the situation yourself and dialling back the charge current on the touchscreen (or finding a better charging source).

    I found this out last weekend, while scrounging a (slow) charge in a condo building at Whistler on a ski trip with our Model S. The first 120V outlet I used was fine, reporting 115V under load. The second and third outlets I used in the same garage both reported 107-108V under load, and this triggered the warning on the dash.

    Words to the wise!
     
  14. adelman

    adelman R 539, S VIN S44, X Sig#1

    Joined:
    Apr 23, 2009
    Messages:
    120
    Location:
    Santa Cruz, California, U.S.A.
    At least in PG&E's territory in California, they have their own set of rules, not dependent on the NEC, for what happens before the meter. I have a 200A service that at the time was fed by a 10kVA transformer shared with a neighbor! As the result of installing a large PV system (36.7kW DC / 30.5kW AC / http://www.solarwarrior.com/), PG&E insisted on upgrading the transformer (they said it couldn't handle the ~25kW from my solar). When confronted over why they put a 10kVA transformer on a 200A service they insisted that the transformer was suitable for delivering 200A to me, but not suitable for taking 180A from me (otherwise it would have been their responsibility to upgrade it, not mine).

    We decided to do a test. We locked out the solar system and applied around 160A of EV charging and other load. 45 minutes later, the transformer on the pole at the end of my driveway was spewing oil and sounded like a percolator.

    b11-r15-14.jpg

    After the hazmat cleanup, PG&E replaced it with a dedicated 25kVA transformer. I'm sure one day I'll smoke that as well; with 5 EVs "full rate" charging them all at once is a 290A load (which I obviously can't do on a 200A service). The good news is that I have two conductors of 500MCM copper (and a somewhat smaller neutral) coming down from the poll.
     
  15. ModelS1079

    ModelS1079 Member

    Joined:
    Jun 23, 2012
    Messages:
    837
    Location:
    Suburban Boston
    So, the town installed the wires from pole to house, two years ago, with plans for electrothermal storage heat and, eventually, an electric car. I think they just dropped the ball the day they put those wires up - two years ago. When the car load was added, all was inspected IN the house by my electrician, by the town's electrician as well, and by the light plant (electricity supplier). And therein lies the error - everyone assumed the post-to-house wire was AOkay, and focused on my panel and in-house wiring to the garage. Which are fine. The post-to-house wires have been UPgraded.

    - - - Updated - - -

    Of course, shared by me to be shared.

    - - - Updated - - -

    Mike K, agreed and perfectly put.
    I do believe that three months ago (smaller forum, early adopters, an appreciation for the thrill of the "What the heck?!") that post would have been fine - BUT I am SO sorry I did not follow-up. Still wiping char from my house and sweat from my brow :redface:
     
  16. Vger

    Vger Active Member

    Joined:
    Apr 10, 2009
    Messages:
    1,682
    Location:
    Salt Spring Island, BC, Canada
    Then your neighbours should have no complaint with you, but they should be rather circumspect about their shared utility and town governance! I certainly hope that the car does not get any blame in this! As a matter of fact, the same thing could have happened if you had installed a new electric oven, rather than an EV!
     
  17. ModelS1079

    ModelS1079 Member

    Joined:
    Jun 23, 2012
    Messages:
    837
    Location:
    Suburban Boston
    #17 ModelS1079, Jan 9, 2013
    Last edited by a moderator: Jan 10, 2013
    Great story and glad that all has ended well, since it easily could have ended with significant damage...

    Hugely interesting. Thank you.

    - - - Updated - - -

    But an oven would have been on my regular circuit board - I have three boards: Regular use, Heating, and - as a subpanel of heating - EV. Pictured here:

    Circuit Boards.jpg

    Left, regular electrical baord, subject to the usual fees.
    Top right, for heating - electrothermal storage, on a town-controlled timer - goes on only 10PM to 6AM, 5.5 cents/kWh.
    Bottom Right - Vroom Vroom Tesla Charger. On a meter - 5.5 cents/kWh 10PM-6AM, else costs peak rate or about 16.5 cents kWh.
     
  18. GeekGirls

    GeekGirls Kid in Candy Store

    Joined:
    Dec 30, 2012
    Messages:
    269
    Location:
    Santa Cruz
    Yikes! I'm sorry about your scare, and I'm glad everyone is safe and sound. I would be very tempted to have everything your installing electrician touched checked by a qualified professional. There should always be a breaker on every circuit, including the one from the street, that shuts off when current exceeds what the lines are rated for. Period. Anything else is a violation of code that should result in an investigation.

    I'm surprised you have your Tesla on a 40A circuit. Are you only charging at 32A? You must have a 50A circuit for 40A charging, as no sustained load is ever supposed to exceed 80% of the rated current for those lines.
     
  19. doug

    doug Administrator / Head Moderator

    Joined:
    Nov 28, 2006
    Messages:
    15,912
    Location:
    Stanford, California
    Any pics of this carnage?
     
  20. mknox

    mknox Well-Known Member

    Joined:
    Aug 7, 2012
    Messages:
    8,552
    Location:
    Toronto, ON
    The electrician or homeowner should ALWAYS report load additions to the local electric utility. Here in Ontario, it is a requirement to take out a permit with the Electrical Safety Authority (usually handled by the electrician). Depending on what is being done, this will trigger the requirement for an inspection, then authorization is given to the utility to re-connect. Having said that, it has always been our practice (I have 33 years at electric utilities) to install residential service conductors sized to the capacity of the main service disconnect. Unfortunately, these type of things are not as uncommon as you might expect. We have a term for it: burn-offs. They are usually related to a bad connection and typically occur at the overhead stack or in the meter socket. (Our new Smart Meters report meter socket temperature and can send an alarm if the problem occurs there). I'm not sure what happened in this case, but I'll bet it was a weak connection. The fact that the utility came back and re-installed larger conductors may have been preventative, or it may mean that they actually were under-sized.


    We sold these thermal storage systems in Toronto back in the '80s and they are staring to come back into fashion with Ontario's Time-of-Use rates. We have a few customers with them.
     

Share This Page