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Converting NEMA 10-50 to 14-50

benimohit

New Member
Apr 21, 2021
3
5
Kent
Hi All, Getting a 2021 Model Y tomorrow and my garage(new house) has a NEMA 10-50 outlet. I am trying to change the outlet to 14-50.

Info:
1. The wiring is 6AWG from circuit breaker(50) to the outlet and then to a hot tub(Circuit breaker is shared) (see the picture added )
2. The box is a plastic box and I dont see any ground wire coming in to the box.
3. there is an unused 110/120 box right by the side of the NEMA 10-50 and this does have ground wire.

Questions:
1. Is it okay to have the shared circuit breaker in this case ?
2. Do I need to have a ground wire for replacing this NEMA 10-50 to 14-50. (if no, then will there be any risk ) ?
3. Can I get the ground wire connection the unused box and use it !

Please enlighten me! thanks :)
 

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Amacharola

Member
Jan 27, 2020
77
40
York, PA
I don’t think you need to go a sub panel route as much as others think. Often, you can install some tandem breakers for some 15/20a circuits to free up space in a panel. Myself, even if installing a NEMA 14-50, is avoid using aluminum and replace with copper if a new ground needed to be pulled anyway. While aluminum CAN be used with most outlets just fine, not all EVSEs can be used with aluminum wiring if you replaced the outlet in the future with an EVSE.
 
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MN-MS100D

Member
Dec 10, 2018
116
72
Minnesota
I would abandon the existing wiring and start over. #6 AL wiring is good for 32 amps and needs PROPER termination techniques to not be a thermal problem for EV charging. AL is the worst application for a load that runs full-out for many hours, then cools down for several hours. The expansion and contraction can loosen the terminations over time and create massive heating if/when it loosens.

Yes, if done correctly with proper preparation of the terminations and proper torqueing, AL poses no problems, but copper is better in every way except cost.
 
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tga

Supporting Member
Apr 8, 2014
3,922
2,763
New Hampshire
This outlet is ugly. I'm surprised no one called out those taped splices. They look too thin/wrong shape for real connectors needed for that heavy wire (ie, Polaris-type).

And to answer the second part of your question, as per most local codes, your ground conductor must be of the same wire gauge as your current-carrying conductors.
Only true for 30A and smaller circuits. Circuits >=30A and <=60A can use 10 ga copper grounds, <=100 can use an 8 ga copper ground (see NEC table 250.122). 6, 8, and 10ga Romex have a 10ga bare ground, 2 and 4 ga have an 8 ga bare ground - Romex® Brand SIMpull® Type NM-B Cable | Southwire

While aluminum CAN be used with most outlets just fine, not all EVSEs can be used with aluminum wiring if you replaced the outlet in the future with an EVSE.
You need to use terminals that are AL rated. The Wall Connector is not AL rated; copper wire only.

I would abandon the existing wiring and start over. #6 AL wiring is good for 32 amps and needs PROPER termination techniques to not be a thermal problem for EV charging. AL is the worst application for a load that runs full-out for many hours, then cools down for several hours. The expansion and contraction can loosen the terminations over time and create massive heating if/when it loosens.

Yes, if done correctly with proper preparation of the terminations and proper torqueing, AL poses no problems, but copper is better in every way except cost.
You are correct in that the 6ga AL is rated for 40A at 60C, but if your wire and terminals are rated for 75C, you can run it at 50A (see NEC table 310.15(B)(16)). I have a 50A range outlet fed with 6ga AL on a 50A breaker, but the breaker and outlet have 75C terminals. Without looking at it, I'm pretty sure it's SEU cable with a 10-50. When I redo the kitchen, I'll replace with a 14-50 and copper.

The alloys used in modern AL wiring have a much lower thermal coefficient of expansion than the stuff from the 70's. It's used all the time for high-current wiring for main feeders and subpanels without issue. Your house probably has it.
 
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