Gen 3 Wall Connector Wire and Conduit Question

[Mrbrock]

Um, you dont downsize a breaker for constant load vs intermittent. No need to find a 44A breaker. I think you are making too big of a deal with the allowance to use a 60A breaker with 55A wire. At the end of the day, the wire is rated at 55A so now matter how large the breaker or any other piece of equipment in the circuit, you wouldn't be able to use it at higher than it is rated. And you downrate accordingly for constant. If you want to charge at 48A with a 60A breaker but 55A wire, that wouldn't meet code so you couldn't use it. Couldn't install it because it wouldn't pass code. If you follow code, you prevent risks.

 

[thecavalry]

Um, you dont downsize a breaker for constant load vs intermittent. No need to find a 44A breaker. I think you are making too big of a deal with the allowance to use a 60A breaker with 55A wire. At the end of the day, the wire is rated at 55A so now matter how large the breaker or any other piece of equipment in the circuit, you wouldn't be able to use it at higher than it is rated. And you downrate accordingly for constant. If you want to charge at 48A with a 60A breaker but 55A wire, that wouldn't meet code so you couldn't use it. Couldn't install it because it wouldn't pass code. If you follow code, you prevent risks.

We are saying the same thing here. Nobody said to look for a 44a breaker.

 

[Mrbrock]

Understood. So let’s dig a little deeper into the continuous load situation and this allowance to serve “55a wire” with a 60a breaker.

Say we have a circuit consisting of 6/2 romex supplying our wall connector. Let’s accept the specification that the maximum safe current that can flow continuously through this wire is 0.8*55 = 44a. Now we need to provide over current protection for this circuit to avoid overheating and fires. Can we find a breaker that allows 44a continuous to flow but does not allow 48a continuous to flow?

Will long term current flow at > 80% of a breaker’s rating cause it to trip? Is this designed into the interruption mechanism somehow?

If this is the case, and the illusive 55a breaker would have offered proper protection, then using a 60a instead would allow the 48a continuous current case, which we claim is unsafe.

@thecavalry yes we are, @rjpjnk is not. See red text above.

 

[rjpjnk]

@thecavalry yes we are, @rjpjnk is not. See red text above.

Mrbroc, I think you may have missed my whole point if you think I am suggesting to downsize the breaker to 44a (or 48a). That is certainly not my intention. To be clear, my understanding is that for a constant load circuit, the wire and the breaker are required to be rated at 1.25 times the expected current, i.e., 48a circuit gets a 60a breaker. I am not questioning this.

The highlights in red are out of context.

 

[Mrbrock]

Mrbroc, I think you may have missed my whole point if you think I am suggesting to downsize the breaker to 44a (or 48a). That is certainly not my intention. To be clear, my understanding is that for a constant load circuit, the wire and the breaker are required to be rated at 1.25 times the expected current, i.e., 48a circuit gets a 60a breaker. I am not questioning this.

The highlights in red are out of context.

I guess I am lost as to why you are trying to explain why you need a 44A breaker to protect a 55A circuit (using the 80% rule was my guess). The highlights in red are not out of context, it is exactly what you posted. If there was a different point you were trying to prove with bringing in the 44A breaker I cannot see that.

 

[rjpjnk]

I guess I am lost as to why you are trying to explain why you need a 44A breaker to protect a 55A circuit (using the 80% rule was my guess). The highlights in red are not out of context, it is exactly what you posted. If there was a different point you were trying to prove with bringing in the 44A breaker I cannot see that.

No, you're interpreting it backwards. I am saying you need a 55a breaker to protect a 44a continuous load circuit, and to the extent that a 55a breaker safely protects the 44a constant load circuit, upping this to a 60a breaker will protect at 48a. But our 6/2 NMB should not have 48a flowing constantly. So there is a bit of an inconsistency here.

I'd rather not further clutter up this thread as it's a subtle technical point that is probably not of much interest to a wide audience. If you would like to PM me I will try to explain it better. For now, we all know the right breaker is 60. Maybe just leave it at that.

 

[marx1]

I just ordered my MYLR, but I've been doing electrical work for a long time... There is a LOT of correct, and incorrect info in this thread. First of all, don't trust anyone on the internet blindly. Talk to/hire an electrician. With that said, here's correct info:

Wire must be rated at or above the branch circuit protection device. (Circuit breaker). Longer runs require bigger wires due to voltage drop. Anything less than 50' can generally use 6awg.

Specific to 6awg NMC (Romex) is rated to 55a due to wire heating/National electric code (NEC). This limits it to a 50a breaker. If you want full rate charging, you must use a minimum of 2x 6 AWG THHN (90c rated) copper (hot wires, red and black, or both black) and 1x 10awg ground (Green, must be 8awg per NEC), that is rated at 75a, on a 60 amp breaker. This will all fit into a 3/4" conduit( ANY kind), but 1" is much easier to do. Use stranded wire, not solid. These limits are because the maximum designed branch circuit load shall not exceed 80% of the protection device rating for these kinds of loads (Appliances/Motors etc)

You can run 4 AWG NMC (Romex/Service entrance cable - as long as it's copper, NO aluminum, the charger is not rated for it) or THHN. 4awg NMC is 60c rated @ 70a, and THHN is 90c @ 95a

In most places you need a permit as well.

If you don't fully understand what your are doing, HIRE AN ELECTRICIAN TO DO THE WORK! There is a lot more to this than just running wire and plugging it in due to wire size, conduit, routing/wire protection, where you can/can't drill holes in structural hose members etc. It's not worth burning your house down if you get it wrong.

 

[djr-atlantic]

I've read through some of the wiring threads and I think it's given me a better understanding about the Tesla Wall Connector materials/installation. I am hiring an electrician to do the work, most likely one that is on Tesla's recommended list. There will be a permit and final inspection. It may not be as clean looking an install as I'd like, but it's a garage. My electrical panel is in an unfinished basement and the attached garage is drywalled, probably about 50 feet of wire needed.

I'll need to get some clarification from the contractor about the items I highlighted. I'm not sure what is meant by "RX > THHN", but prior to getting the estimate he said it would be 6/3. Anyone see any red flags in this part of the estimate?

Thanks!

 

[rjpjnk]

I would like to see more specifics listed, like whether conduit will be used and what type, and specifically what breaker will be used.

In my experience, 6/3 generally refers to packaged multi-conductor wire such as Romex, whereas THHN refers to individual wires typically run in conduit. I don't know what the "RX >" prefix refers to, but you do not want to end up with 6/3 Romex for any part of the circuit or you will not have a 60 amp circuit. Also, the third conductor is unnecessary and would be a waste of money.

The clause about the maximum output being adjusted voiding warranty seems suspicious. What is that supposed to mean? On a 60 amp circuit every value the Wall Connector can be configured for should be valid.

Personally I would confirm two things: (1) that the breaker will be 60 amps, and (2) that 6 gauge THHN will be run in conduit for the entire length.

 

[marx1]

I found that some people refer to nonmetallic sheathed cable (aka Romex) as RX. 6/3 RX/Romex/nmsc is NOT rated for use in an EV charger. It must be rated at 125% of the load per NEC, or 60 amps. 6/3 nmsc is rated at 55 amps, as it's 60c wire. They must use #6 THHN in conduit, or 4/2 nmsc.

With the adjustment comment, They are trying to get around running thhn by adjusting it lower - down to 40a charge, not 48a. If you adjust it up to 48a, you're going over the rating of the wire and can cause a fire, and the electirican doesn't want to be responsable for that. Honestly, it's SUPER shady. They need to run it correctly, or size the breaker down to 50a, not 60a.

 

[marx1]

I also found that my state has a very cool checklist that has a good list of things to check it if anyone wants to look at it:

https://static.business.ca.gov/wp-content/uploads/2020/02/OPR-Checklist.pdf

 

[rjpjnk]

That is what I suspected. If he intends to run Romex 6/3 and hide behind the max current statement I'm thinking this electrician is being deceptive, and that's worse than unaware. What really gets me is the estimate is calling it a "60 Amp Dedicated Circuit". How can this be?

 

[Mrbrock]

He’s doing this and is recommended by Tesla? Sounds like he should be taken off that list.

 

[marx1]

What really gets me is the estimate is calling it a "60 Amp Dedicated Circuit". How can this be?

Because technically it is. It's a 60a circuit breaker that has nothing else on it besides the charger. The issue is wire isn't correct, and that's where the issue is at.

 

[Mrbrock]

Because technically it is. It's a 60a circuit breaker that has nothing else on it besides the charger. The issue is wire isn't correct, and that's where the issue is at.

So if the wire isn’t correct it’s not a 60A dedicated corcuit. At best it’s a 55A dedicated circuit or as said earlier in this thread, lowest common denominator would be a 50A dedicated circuit.

 

[djr-atlantic]

Thanks for giving feedback on the estimate above! You seem to share my concerns on the highlighted areas. I'm trying to get another estimate before I ask him for clarification. I do wonder if this is created from a basic form they use and didn't edit it properly for my application. Since the permit is included I WAS feeling secure thinking it would HAVE to be done to code.

 

[rjpjnk]

Because technically it is. It's a 60a circuit breaker that has nothing else on it besides the charger. The issue is wire isn't correct, and that's where the issue is at.

My point is that I don't believe it should be declared a "60 amp circuit" on a proposal unless the entire circuit meets the electrical code standards for 60 amps. If the wire is too small I'd argue it is not a 60 amp circuit. Is this not the case?

 

[Rocky_H]

I see a lot of people jumping to crazy conclusions on this, with just guesses and assumptions but without information.

You notice there is NO mention of the gauge of wire anywhere in that estimate? So you all have no idea if the wire is sufficient or not. People are screaming that if it's Romex, it's wrong. But what if it were 4 gauge Romex? That would be fine, but you don't know, do you?

So yeah, that wire needs clarification of exactly what it is. These are very simple to tell if it meets the qualifications for a 60A circuit or not, but it's not specified there enough to tell right now. And yes, find out what breaker too.

It's fine to say it's a "dedicated 60A circuit" if that's what is being installed.

 

[Mrbrock]

I see a lot of people jumping to crazy conclusions on this, with just guesses and assumptions but without information.

You notice there is NO mention of the gauge of wire anywhere in that estimate? So you all have no idea if the wire is sufficient or not. People are screaming that if it's Romex, it's wrong. But what if it were 4 gauge Romex? That would be fine, but you don't know, do you?

So yeah, that wire needs clarification of exactly what it is. These are very simple to tell if it meets the qualifications for a 60A circuit or not, but it's not specified there enough to tell right now. And yes, find out what breaker too.

It's fine to say it's a "dedicated 60A circuit" if that's what is being installed.

Yes, but he said the electrician told him prior to the quotation that it would be 6/3. If this changed, it should be noted in the quotation.

 

[marx1]

Yes, but he said the electrician told him prior to the quotation that it would be 6/3. If this changed, it should be noted in the quotation.

6/3 nonmetallic sheathed cable. It is not rated for the current, as it's only 60c rated, so it's 55a max.