Charging on 110 outlet

[mspohr]

A proper wire ampacity table will have amp ratings also based on insulation heat specifications. So it isn't just the wire gauge, but also insulation heat capabilities. Also bear in mind that NEC tables are meant for in building wiring, not extension cords. And then you have resistance per length of wire. So you could be drawing 16A from an extension cord, but at the other end of a 100' long cord, the breaker could be seeing a 20A draw. Fwiw, in building romex is normally 14 gauge for 15A circuits, and 12 gauge for 20A circuits.

One minor point... the amperage won't change with longer cords... you put 20amps in and you get 20 amps out the other end.
OTOH, you do get a voltage drop with longer cords. You could put in 120 volts and only get out 100 volts if you have a high current draw and a skinny wire.
Here's a good guide to extension cords:
Buying Guide: Extension Cordsat The Home Depot

Tesla charging would be considered "Extra Heavy Duty".

Tesla limits charging from 120volts to 12 amps which is 80% of the 15 amp capacity of these sockets required for continuous duty. For this, a short 14 gauge extension cord is minimum... better to have a 12 gauge cord.

 

[steilkurve]

Question. If I do get a 14-50 RV-type extension as the ones referenced in this thread, will I have to adjust the the amperage to 40 on the charging screen when plugged into a 14-50 oven outlet? What about if I put Tesla's 5-15, 5-20 or 5-30 adpater on the other end? After reading a few more threads, I'm confused as to when I'd have to adjust amperage with an extension cord. Is it only when no Tesla adapter is used? Thanks.

 

[Cosmacelf]

You always use a tesla adapter on the UMC, and the car will default to the amperage of the adapter, 40A for the 14-50, 12A for the 5-15, etc. So no need to adjust when plugged into a 14-50 outlet.

Note that regardless of the adapter amperage rating, the car also remembers the amp setting for the last charge at that location. So if you set it to 12A, it will then default to 12A at that location until you change it regardless of the adapter you are using.

 

[steilkurve]

You always use a tesla adapter on the UMC, and the car will default to the amperage of the adapter, 40A for the 14-50, 12A for the 5-15, etc. So no need to adjust when plugged into a 14-50 outlet.

Note that regardless of the adapter amperage rating, the car also remembers the amp setting for the last charge at that location. So if you set it to 12A, it will then default to 12A at that location until you change it regardless of the adapter you are using.

Ok. Thanks. Very helpful.

 

[steilkurve]

Yes. Good planning has options.

When charging on 120v I try to find an outlet close to the load center or a single outlet (hopefully a 5-20) on a particular branch circuit such as a washing machine or microwave. I always continuously monitor and check all connections for excessive heat and I always travel with a 50' UMC to reduce the probability of having to use an extension. If I need to reach out >50', I deploy a 50' 12AWG 5-20 molded ended extension for both 120v and 240v charging.

Where do you get a 50' UMC?

 

[TexasEV]

Where do you get a 50' UMC?

Quickchargepower.com will modify your UMC.

 

[Cosmacelf]

Yeah, I like the quickchargepower solution. Very elegant.

 

[smilepak]

Or NEMA 14-50 extension cord Heavy-duty NEMA 14-50 extension cord for Tesla, 20 ft.

 

[Rocky_H]

It's total resistance of the circuit to the car that will trigger the 75% charge current (12A->9A) safety feature. With a good starting 120 outlet (circuit) I have successfully charged with 50' #12 and #14 extension cords. Those #10 cords are pretty heavy and will only save you from 9 Amp charging on a few threshold circuits.

I recommend a good #12 50' cord with quality plug and receptacle. Here is one example: US Wire 74050 12/3 50-Foot SJTW Yellow Heavy Duty Lighted Plug Extension Cord - - Amazon.com

So, from earlier in the thread, I discovered that my cords at home were 16 gauge. Thanks for the link to the 12 gauge cord, Cottonwood. And it’s a link that supports EFF—excellent. I just ordered that, along with this 12 gauge adapter cable, so I can use the Tesla 5-20 adapter through that cord to a 5-20 outlet.
http://smile.amazon.com/gp/product/B00439KIF6?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00
I now need to actually go order the 5-20 UMC adapter from Tesla.

 

[Nigel Tufnel]

I use Tesla's adaptor (40 amp limit) on a dedicated 50amp home circuit. Periodically I find that I'm drawing 30 amps instead of 40 (although I'm not aware of any changing variable) and I've never known why. After reading this thread's posts I still don't know why, but have some jargon I can use to rationalize the problem, and that makes me feel better. Thank you.

 

[FlasherZ]

I use Tesla's adaptor (40 amp limit) on a dedicated 50amp home circuit. Periodically I find that I'm drawing 30 amps instead of 40 (although I'm not aware of any changing variable) and I've never known why. After reading this thread's posts I still don't know why, but have some jargon I can use to rationalize the problem, and that makes me feel better. Thank you.

See the FAQ (referenced in my signature, or here for information on charging reductions.

- - - Updated - - -

So, from earlier in the thread, I discovered that my cords at home were 16 gauge. Thanks for the link to the 12 gauge cord, Cottonwood. And it’s a link that supports EFF—excellent. I just ordered that, along with this 12 gauge adapter cable, so I can use the Tesla 5-20 adapter through that cord to a 5-20 outlet.
http://smile.amazon.com/gp/product/B00439KIF6?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00
I now need to actually go order the 5-20 UMC adapter from Tesla.

Just as a word of warning - while the 12 AWG conductors may support that current level, you should be careful. Once a year at a car show, I charge at 16A on a 10AWG extension cord set. When I unplug at the end of the show (after 6 hours or so), the plugs are VERY hot and have somewhat softened the plugs on them. So be careful with the continuous currents being sent through the cords. You might find yourself replacing the plugs and receptacles with heavy-duty ones.