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Ungrounded 5-15?

Discussion in 'Model S: Battery & Charging' started by lklepner, May 7, 2014.

  1. lklepner

    lklepner New Member

    Feb 11, 2014

    I went on a road trip recently and one of the places we stayed had ungrounded 15-5 outlets. Taking a look at the breaker panel I saw a note that the entire apartment was ungrounded except for GFI outlets in the kitchen and bathroom. When I tried charging off one of the non-GFI outlets I found the car would not accept it.

    I've read that the neutral and ground wire of household wiring and connected at the breaker panel. If this is the case would it be possible to make an 15-5 adapter which connects the ground pin to the neutral pin so that I could have charged using these otherwise ungrounded outlets?

  2. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

    Jun 21, 2012
    Using such an adapter (a "dummy plug") will allow the car to charge.

    Even GFI's may be ungrounded, but they provide protection in ensuring that power can't flow from the hot without returning through the neutral. These GFI's will be marked "no equipment ground" but will provide safety.

    Is it safe? That depends on all sorts of things - whether the outlets are 2-prong or 3-prong, whether the outlet box is grounded, etc. You must also MAKE SURE that the hot and neutral aren't reversed (as they were in my aunt's home wired in the 1940's. If they're reversed and you bond hot to ground, you'll potentially make the chassis of some appliances become 120V relative to ground.

    At a local car show, the municipal utility provides me with 120V circuits from a 3-wire feed. The panel they supply does not have ground bonded to the neutral (which would normally happen, but most appliances don't complain). I bound ground to neutral there for them to make charging work.

    Bottom line, you can make the car charge but you'd better make sure that neutral is truly neutral before you tie the car's ground to the neutral. It's not to code.

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