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Question about NEMA 14-50

Skr1988

New Member
Apr 25, 2021
2
2
Texas
Good evening. I recently had an electrician come out to install a NEMA 14-50 outlet in my garage for my Model 3 I get next week.

He installed a 14-50 outlet using a 40 amp breaker, and 8 gauge wire rather than the 6-3 gauge. The outlet is about 1 foot away from the breakerbox.

Is this a problem? Should I have someone come out and redo the installation? This electrician said the wire and breaker combination would be fine.

Thanks for any assistance!
 

skriefal

Member
Mar 29, 2021
17
19
Utah, USA
It should work okay if you don't draw more than 32 amps continuous, and assuming that the electrician hooked things up correctly. But I wouldn't want a 50-amp 14-50 outlet on a 40-amp breaker or with 8-gauge wiring. Hopefully it was cheap!
 
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miimura

Well-Known Member
Aug 21, 2013
6,270
5,900
Los Altos, CA
This is legal and safe with the included Mobile Connector since it only draws 32 amps. However, don't use another plug-in EVSE that can draw 40 amps. The electrician should have given you the option for the full 50 amps versus the 40 amps he provided.
 
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Kevy Baby

Dis-Member
Aug 11, 2019
1,943
1,929
Brea, CA
Worth throwing in that the Corded Mobile Connector is capable of up to 40 amps, assuming your car can handle it (the SR and SR+ models are maxed at 32 amps).

Personally I think it is short-sited thinking (and potentially dangerous) to leave it at the 40 amps: I would have it corrected.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
8,895
9,907
Riverside Co. CA
You should have that electrician explain to you in something other than "it will be fine" why they did what they did. Whether this matters or not sort of depends on what model 3 you are getting. The SR+ only charges at 32amps max on a L2 connection (which your 40 amp breaker setup will do).

The real question is why did they do it that way (load calculations? Cost?). If you wanted a 50amp breaker connected to the 50 amp 14-50 along with the appropriate wire, and they didnt do that, you should have stopped them and asked "why" and either told them what you expected right then or had a better understanding of why they did it that way (what you were paying for).
 

Scrannel

Member
Sep 27, 2019
161
62
Malibu, CA United States
Right after I got my M3P and realized 120v wasn't going to cut it, when to my local electrical supply. (In Los Angeles one is allowed to DIY and permit later) They asked what the car was. Box rating. How far was the throw etc. Then handed me 6' of 6-gauge Romex and a 50 amp breaker. I attached to a high-end 14-50 outlet where I keep my UMC permanently plugged-in. Doesn't even get warm. It was odd walking into an electrical supply and have the over-the-counter guy know a lot about EVs already. But, that's Los Angeles. Maybe electrical shops will become the new Pep Boys.
 
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Gauss Guzzler

Member
Dec 27, 2020
211
260
Thousand Oaks, California
He installed a 14-50 outlet using a 40 amp breaker, and 8 gauge wire rather than the 6-3 gauge. The outlet is about 1 foot away from the breakerbox.
That is completely legal, completely safe, and completely adequate for your purposes at this time.
It is not ideal however because you'd need 6AWG and a 50A breaker if you ever change to a 40A portable charger or convert the outlet to a junction box for a 40A capable wall charger.

As others noted, this probably happened because he only had a 40A breaker handy at the time. There's no meaningful cost difference and likely no limitations from the main panel.
 

Sophias_dad

Supporting Member
Jul 29, 2018
1,129
1,040
Massachusetts
you'd need 6AWG
Not if its individual conductors in conduit. Heck, with that short a run I think its legal to run NM-B through the conduit(although then you need to consider the 60C limit of the NM-B, which means 6awg would be needed).

8 awg THHN in conduit is good for 50 amps. That said, I'd probably go bigger anyway.

 

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