When I will be driving up to my family’s vacation house next month I will also be charging off of an electric dryer outlet. Luckily the dryer at the house has been changed to a gas dryer, but the old NEMA 10-30 outlet is still there. Rather than get a NEMA 10-30 extension cord I’m going to get a NEMA 14-50 extension cord instead along with a NEMA 10-30 to 14-50 adapter. I’d rather have a 14-50 extension cord and just purchase adapters for it as necessary.
Here’s the extension cord I’m getting: https://www.amazon.com/dp/B0024ECIP0/ref=cm_sw_r_cp_api_WGB3AbM491SS3
And here’s the adapter:
If you go the same route as me then double check the dryer outlet to make sure you get the correct kind of adapter. Also since my solution will utilize the 14-50 plug that comes with the mobile connector you absolutely need to make sure you decrease the amp draw on your Model 3. Since the 14-50 plug will be in my mobile connector my Model 3 will assume it can charge at the full 32 amps that the mobile connector is capable of. Because I will actually be plugging into a NEMA 10-30 outlet the most I’ll be able to have the Model 3 draw is 24 amps. Even at just 24 amps that should allow me to charge at a rate of 22 miles per hour.
i'm doing the same thing essentially. The 10-30 relocated to the garage converted to 14-30 as the ground wire was actually there just never hooked up and tested ok with a multimeter. I have that same extension just 15 feet as that what I needed - its really well built and I went w 14-50 so I can use it anywhere such as an RV park if ever needed with adapters on either end. You can actually cut the neutral prong so the 14-30 tesla adapter plug will fit into the 14-50 cord which is what I did yet the tesla branded adapter keeps the Amps at 24 Amps which is safe (search for others posting about that here if you wish, o/w I had adapters on both ends now just this one: https://www.amazon.com/gp/product/B00STD8CXC/ref=oh_aui_search_detailpage?ie=UTF8&psc=1