Almost all campgrounds now have 14-50s and TT-30s on all sites. There's more and more RV's made to operate with 125v 30A these days.
This will not work, unfortunately. This will place the L1 from the 5-15 to both L1 and L2 on the 14-50, and the N from the 5-15 to the N on the 14-50. The Tesla will see 0 volts across L1-L2. To use a TT-30 on a Tesla you will need to make a custom adapter that no one will really be able to sell because of its configuration. You need to connect L1 to L1 and N to L2 on the 5-15 and 14-50, respectively. If this customized adapter were to be used on an RV it would cause very serious problems.
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All this Quick220 talk has me intrigued... how do you find 2 outlets that are on opposite phases? Do you just keep plugging the Quick220 in everywhere until you find a pair that works?
Or is there some ready-made device you can use that tells you the phase of a particular outlet? (Probably not to difficult to build one using an Arduino and a H11AA1).
Quick nit-pick, they're not "opposite phases", they're "opposite legs" of a center-grounded 240V L-L voltage.
They use pilot lamps and/or other electronic checks to ensure there is 208V or 240V between L1/Hot on receptacle 1 and L1/Hot on receptacle 2. If you have the same leg, you'll get 0V between L1/Hot on both plugs. There is no ready-made device you can use, because it is AC (a symmetrical wave of voltage centered on a grounded conductor) and you can't tell without having two sources to compare.
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This adapter will not work since they tie both L1 and L2 pins of the 14-50 to the one hot pin of the TT-30. The UMC will see this adapter as providing no power.
Thanks for pointing this out, I didn't see your reply until I wrote mine.
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That walmart adapter just seems too easy. Could flasherZ or one of the other experts chime in whether this would work for us and deliver 120v at 30 amps? Based on my understanding, all we have to do is dial down the amperage to 24 (80% of 30amps, as always)? I also found this
http://www.evseadapters.com/adapters-for-tesla-model-s.php. The tt-30 adapter on that page converts to the normal 120v outlet it looks like, so as described in this thread, this should only privde the power of a normal 120v outlet (because of the tesla umc thinking its normal 120v).
Here's how you can build the adapter... get a short length of 10/3 SOOW cord, a molded TT-30 plug, and a molded 14-50 receptacle. Ground on TT-30 goes to ground on 14-50, L1/Hot/Brass on TT-30 goes to L1/Hot/Brass/Black on 14-50, and Neutral/Silver on TT-30 goes to L2/Hot/Brass/Red on the 14-50. Mark the cable "FOR TESLA CHARGING ONLY - WILL DESTROY OTHER APPLICATIONS" very clearly. If the UMC turns red when you plug it in, reverse L1 and L2 on the 14-50. The UMC will send a 40A pilot signal, so be sure to dial it to 24A max.
Keep in mind all my usual warnings -- this violates NEC and can cause your insurance to deny your claim should you suffer a loss while using it, even if the adapter is not the cause of the loss.