NEMA 14-50 is dead - all hail NEMA 6-50

[pdx_m3s]

14-50 is the best general purpose option, as it can be used for any 50-amp appliance because it can run both 240v and 120v simultaneously (hence the need for 4 wires). However, you're right it is unnecessary for EV chargers, as those only require 240v.

 

[qdeathstar]

Seems to me the best plug for EVs would be a twist lock plug...

 

[MorrisonHiker]

Seems to me the best plug for EVs would be a twist lock plug...

I don't know if it is still current but the electrical code mentioned the outlet must be non-locking.

From .625.44 Electric Vehicle Supply Equipment Connection.

In 625.44, the EV charging equipment can be cord and plug connected in accordance with 625.44(A) or 625.44(B). Both of those sections offer different installation methods based on equipment voltage but still have one thing in common: They both require any receptacle used for the cord and plug connection to be non-locking. Any other equipment configuration not covered in 625.44(A) or 625.44(B) must be permanently wired and fastened in place to the supporting surface, wall, pole, or other structure.

625.44 Electric Vehicle Supply Equipment Connection. Electric vehicle supply equipment shall be permitted to be cord- and plug-connected to the premises wiring system in accordance with one of the following:

(A) Connections to 125-Volt, Single-Phase, 15- and 20-Ampere Receptacle Outlets. Electric vehicle supply equipment intended for connection to nonlocking, 2-pole, 3-wire grounding-type receptacle outlets rated at 125 V, single phase, 15 and 20 amperes or from a supply of less than 50 volts dc.

(B) Connections to Other Receptacle Outlets. Electric vehicle supply equipment that is rated 250 V maximum and complying with all of the following:

(1) It is intended for connection to nonlocking, 2-pole, 3-wire and 3-pole, 4-wire, grounding-type receptacle outlets rated not more than 50 amperes.

(2) EVSE is fastened in place to facilitate any of the following:

1. Ready removal for interchange
2. Facilitation of maintenance and repair
3. Repositioning of portable, movable, or EVSE fastened in place

(3) Power-supply cord length for electric vehicle supply equipment fastened in place is limited to 1.8 m (6 ft).

(4) Receptacles are located to avoid physical damage to the flexible cord.

All other electric vehicle supply equipment shall be permanently wired and fastened in place to the supporting surface, a wall, a pole, or other structure. The electric vehicle supply equipment shall have no exposed live parts

 

[qdeathstar]

wonder why that is code... locking receptacles ensure that the plug is fully seated.... a straight blade plug can sometimes become loose, creating a high resistance connection or a shorting hazard if something falls between the blades. I would be interested to know the rational...

But it also explains why tesla doesn’t offer twist lock connectors for their charger....

 

[MrMassTransit]

This is a wild guess, but maybe it is related to concerns about the vehicle driving away/rolling away with the cord still connected? If the cord is non-locking, it should hopefully pull from the socket with a minimum of damage.

 

[yuhong]

This is a wild guess, but maybe it is related to concerns about the vehicle driving away/rolling away with the cord still connected? If the cord is non-locking, it should hopefully pull from the socket with a minimum of damage.

My attempt at adding locking outlets to the NEC 2020 was denied. Using a NEMA 14-50 outlet for EV charging means there is no risk of open neutral unlike with RVs.

 

[qdeathstar]

My attempt at adding locking outlets to the NEC 2020 was denied. Using a NEMA 14-50 outlet for EV charging means there is no risk of open neutral unlike with RVs.

EVa don’t use a neutral, RVs do... ??

 

[yuhong]

EVa don’t use a neutral, RVs do... ??

Yea, RVs uses 120V, EVs use the 208V/240V.

 

[qdeathstar]

Yea, but I’m sorry I’m not following what you are saying in your first post?

 

[yuhong]

Yea, but I’m sorry I’m not following what you are saying in your first post?

Open neutral is a condition where the neutral in a split phase 120/240 system is disconnected, causing one phase to show a lower voltage and one phase to show a higher voltage. This often causes 120V equipment to be damaged. However, the phase to phase 240V voltage is not affected.

 

[strider]

Well, for your own use at home, you can always just buy cable with 3 wires only, and leave out the neutral wire. But you would certainly need to prominently and permanently mark your outlet accordingly.

This is what the electrician here did 3 years ago. Dropped in 2 x 14-50's into our garage on either side of the roll up door, no neutral wire, and labelled them no neutral present, for EV charging only. Both the Roadster, Gen 1, and Gen 2 Model S UMCs have been quite happy.

 

[qdeathstar]

Open neutral is a condition where the neutral in a split phase 120/240 system is disconnected, causing one phase to show a lower voltage and one phase to show a higher voltage. This often causes 120V equipment to be damaged. However, the phase to phase 240V voltage is not affected.

And how does that relate to a 14-50?

 

[user212_nr]

Seems to me the best plug for EVs would be a twist lock plug...

I just got one of those installed.

I like it a lot, but one observation is that it is actually less "secure" than a regular, non-locking plug of the same capacity. What it is good for, despite the name, is actually removeability. All you need is twist-to-unlock (its less than a 1/4 turn) rather than trying to wiggle the plug out of the outlet. The 14-30 plug is practically non-removable from its outlet. If you have a cover (outdoors) its weatherproofing is comparable to the locking plug, maybe a bit less.

 

[yuhong]

And how does that relate to a 14-50?

The NEMA 14-50 has the neutral in it, which RVs use to get 120V. EV charging don't use the neutral and instead use 208V or 240V.

 

[qdeathstar]

I just got one of those installed.

I like it a lot, but one observation is that it is actually less "secure" than a regular, non-locking plug of the same capacity. What it is good for, despite the name, is actually removeability. All you need is twist-to-unlock (its less than a 1/4 turn) rather than trying to wiggle the plug out of the outlet. The 14-30 plug is practically non-removable from its outlet. If you have a cover (outdoors) its weatherproofing is comparable to the locking plug, maybe a bit less.

when a twist lock is installed, it is locked into place so that nothing can get behind the plug and the plug can’t work itself free. A strait blade plug can come loose from its receptacle...

 

[dmurphy]

This is a wild guess, but maybe it is related to concerns about the vehicle driving away/rolling away with the cord still connected? If the cord is non-locking, it should hopefully pull from the socket with a minimum of damage.

Agreed, but since the plug on the Tesla mobile charger is socketed, that's a bit of a moot point.

In other words, in event of a runaway vehicle, I'd expect the mobile connector's socket to act as a kind of breakaway. The twist lock piece would remain in the wall socket, but the mobile connector would go with the runaway car...

 

[user212_nr]

when a twist lock is installed, it is locked into place so that nothing can get behind the plug and the plug can’t work itself free. A strait blade plug can come loose from its receptacle...

I have both the twist-lock (L14-30) and the 14-30 regular. The twist lock goes in and out with a simple twist, but the regular plug requires some heavy force to plug and unplug. Its not like your regular 2/3 prong NEMA 5-15 plug that you can pull out easily.

The locking plug won't come out if you pull on it at all, but would be vulnerable to a twist motion. The regular plug is not vulnerable to a twist of the cord, and resists being pulled on.

That's just my impression, neither have come loose. L14-30 is used for generators where you will want to remove the cable frequently, whereas 14-30 is designed for dedicated appliances that will not often be removed. That's why so many complain about having to remove their 14-30/14-50 plugs.

Plus, the locking plug requires the wire to go straight out (at least 1 foot from wall), whereas the non-locking plug can stay flush against the wall with 90 degree turn.

 

[yuhong]

I have both the twist-lock (L14-30) and the 14-30 regular. The twist lock goes in and out with a simple twist, but the regular plug requires some heavy force to plug and unplug. Its not like your regular 2/3 prong NEMA 5-15 plug that you can pull out easily.

The locking plug won't come out if you pull on it at all, but would be vulnerable to a twist motion. The regular plug is not vulnerable to a twist of the cord, and resists being pulled on.

That's just my impression, neither have come loose. L14-30 is used for generators where you will want to remove the cable frequently, whereas 14-30 is designed for dedicated appliances that will not often be removed. That's why so many complain about having to remove their 14-30/14-50 plugs.

Plus, the locking plug requires the wire to go straight out (at least 1 foot from wall), whereas the non-locking plug can stay flush against the wall with 90 degree turn.

I had a thread on NEC 2020:
https://teslamotorsclub.com/tmc/threads/who-would-like-to-charge-on-locking-nema-outlets.147964/

 

[qdeathstar]

I have both the twist-lock (L14-30) and the 14-30 regular. The twist lock goes in and out with a simple twist, but the regular plug requires some heavy force to plug and unplug. Its not like your regular 2/3 prong NEMA 5-15 plug that you can pull out easily.

The locking plug won't come out if you pull on it at all, but would be vulnerable to a twist motion. The regular plug is not vulnerable to a twist of the cord, and resists being pulled on.

that’s because the plugs for most EV chargers are new. But, look at your old range outlet... a lot of them end up not being fully seated to the plug.

Plus, the locking plug requires the wire to go straight out (at least 1 foot from wall), whereas the non-locking plug can stay flush against the wall with 90 degree turn.

not necessarily.

 

[Rogue Synapse]

A relevant question to this thread:

I rent a house and will probably be there for ~3 more years before we build our dream house. My landlord gave me permission to have a circuit/outlet of my choice installed for charging. Our 200A panel is actually quite a long run from my desired location. It only makes sense to get a 6-50 outlet installed, right? And not spend the extra $ on an expensive run of 14-50-capable cabling, because I don't really care that much about future-proofing since I won't be there forever.