The "EV" products tax (more expensive since it is for an EV)

[eprosenx]

Was doing a Google search tonight to answer someone's forum question (for charging in a campground).

This part is basically the same thing (very slightly different internal wiring):

Now you could say the left one is much lower production rate than the right hand one, and you could also say that perhaps the left one has more liability than the right one?

 

[gregd]

What is the difference in wiring, and how do you know? I don't see anything on the Home Depot site that details what's inside, other than the vague statement "Wired Specifically for compatibility with the Tesla charge", whatever that means... The specs, otherwise, appear to be identical.

 

[eprosenx]

What is the difference in wiring, and how do you know? I don't see anything on the Home Depot site that details what's inside, other than the vague statement "Wired Specifically for compatibility with the Tesla charge", whatever that means... The specs, otherwise, appear to be identical.

A TT-30 plug has three pins. Hot, neutral, and ground. The 14-50 has hot, hot2, neutral and ground. So the difference is how they wire them up.

On the RV one they wire both the hots on the 14-50 to the single hot on he TT-30 and the neutral to the neutral. That way, any 120v appliance in the RV works but any 240v appliance would not work since it would have 0v of potential (no voltage).

On the Tesla one, the Tesla only draws power by connecting the charger on the circuit between the two hots. Normally it expects 240v, but it is also fine with 120v. So that version of the adapter ties the Neutral of the TT-30 to one “hot” on the 14-50 and the Hot on the TT-30 to the other Hot on the 14-50. I tested it last night since I have he grey one and it appears the neutral pin on the 14-50 is “floating”. I.e. not tied into anything. (Not sure how that is how I would have done that - I likely would have tied it to neutral)

Is that as clear as mud?

 

[P85_DA]

So how do u modify the cheaper one to work ?​

 

[eprosenx]

So how do u modify the cheaper one to work ?​

Hah, yeah. It is fully molded plastic so I doubt that will be happening. Good idea though!

 

[P85_DA]

So if one were to use the RV version it would charge at 120v? is that what I’m reading from your post above ? Or won’t work at all ?

 

[eprosenx]

So if one were to use the RV version it would charge at 120v? is that what I’m reading from your post above ? Or won’t work at all ?

Won't work at all in the slightest. Because the Tesla totally does not use the neutral pin, it only uses the two hot pins. If the adapter ties the two hots together, then by definition there is zero voltage potential between those pins, so zero volts.

At least that is my assumption of how it is wired. I don't own the yellow one since I don't have an RV.

 

[gregd]

A TT-30 plug has three pins. Hot, neutral, and ground. The 14-50 has hot, hot2, neutral and ground. So the difference is how they wire them up.

On the RV one they wire both the hots on the 14-50 to the single hot on he TT-30 and the neutral to the neutral. That way, any 120v appliance in the RV works but any 240v appliance would not work since it would have 0v of potential (no voltage).

On the Tesla one, the Tesla only draws power by connecting the charger on the circuit between the two hots. Normally it expects 240v, but it is also fine with 120v. So that version of the adapter ties the Neutral of the TT-30 to one “hot” on the 14-50 and the Hot on the TT-30 to the other Hot on the 14-50. I tested it last night since I have he grey one and it appears the neutral pin on the 14-50 is “floating”. I.e. not tied into anything. (Not sure how that is how I would have done that - I likely would have tied it to neutral)

Is that as clear as mud?

Ah, wow. Yes, very clear (I'm an electrical engineer...). This difference really needs to be made clear in their documentation, as I'd be tempted otherwise to get the cheaper version.

You are correct about the Tesla charging equipment not using the neutral pin. I assume that both plugs wire the ground straight through, as that one is definitely required.

I've seen some documentation claim that some adapters are wired "backwards". I presume that the charger might somehow be sensitive to which side gets the hot, and which gets neutral, when it sees only 120v. Is this requirement the same for all Tesla models (I have a Roadster), or do some want it one way, and some the other? Perhaps other manufacturers have it switched? Interesting...

 

[eprosenx]

I've seen some documentation claim that some adapters are wired "backwards". I presume that the charger might somehow be sensitive to which side gets the hot, and which gets neutral, when it sees only 120v. Is this requirement the same for all Tesla models (I have a Roadster), or do some want it one way, and some the other? Perhaps other manufacturers have it switched? Interesting...

Hrm, that I don't know. I have not even tested my adapter yet to prove it works.

In general, I would not think it would care since AC is AC. All it really cares is that between one pin and the other is some amount of voltage (whether that be 120v or 240v) as long as it is within the range the charger can accept.

Now, actually, what I could see to your point would be issues with the safety mechanisims of the EVSE. When it fires up it wants to make sure the ground is good, so it needs to test voltage to ground. To your point, in a 240v setup, it could test from either (or both) poles of "hot" to ground and make sure there is potential there. But in a 120v setup where one leg is neutral (and tied to ground back at the main service entrance panel) then the only way to verify ground would be to test from the one "hot" pole to ground.

You bring up an excellent question now: How does the ground testing work in the UMC Gen 2 lets say. Does it always test from a specific "hot" pin to ground, or does it test from both "hot" pins to ground IF the voltage from hot to hot is 240v, otherwise it only tests from one pin to ground if the "hot to hot" voltage is 120v?