6/2 romex, Gen 3 WC help

[NJM313]

Hello, I am hoping to get some advice on wiring setup for a gen 3 WC. I am getting a lot of conflicting info including speaking with licensed electricians. I am planning to install a 3rd gen WC. Originally I was planning on using 6/2 romex, on a 60amp breaker to get the max 48 amps. Now I am reading that this is no good because of continuous load.

So assuming thats correct, my options are:

-Use #6 THHN wire in conduit
-Install the 6/2 on a 50amp breaker and charge at 40 amps
-Use 4/2 romex which doesnt seem to be available

This sound right? For my application I have to go through a wall or two, so would I need to install conduit through the wall if I went with THHN? If I go with the 6/2 on a 50amp route, do I need to use conduit in the portion of my garage where the wire is exposed?

 

[Jeremy3292]

6-2 UF, which most non-electricians would mistakenly call "romex", is a multiconductor cable rated for 90 deg and suitable for this use. I'd bet that's what the OP's electrician was talking about putting in. That's what my electrician used. The OP didn't say it was NM-B.

6-2 MC would also be fine, though that is less likely to be called "romex" (though I have heard it called that).

Why would you use 6-2 UF cable? That is underground, direct burial cable and is not referred to as ROMEX. ROMEX is literally Southwire branded NM-B cable. The link has already been given previously.

Regardless, 6-2 UF cable has the same ampacity rating as NM-B or “ROMEX” of 55 amps. It is not allowed per NEC code either on a 60 amp circuit. The ampacity of the conductors cannot exceed 60 degrees. That is bc all of the wires are sheathed together. So if the temperature of a each individual conductor is 60 degrees, the cable itself will be much hotter than 60 degrees. So the cable itself is rated for 90 degrees but the individual conductors cannot exceed 60 degrees. THHN wires are not sheathed together so they carry a 90 degree rating and thus have a higher ampacity. See the same chart I already showed above.

 

[qdeathstar]

6-2 UF, which most non-electricians would mistakenly call "romex", is a multiconductor cable rated for 90 deg and suitable for this use. I'd bet that's what the OP's electrician was talking about putting in. That's what my electrician used. The OP didn't say it was NM-B.

6-2 MC would also be fine, though that is less likely to be called "romex" (though I have heard it called that).

Now your just making stuff up. I guess you should of just led with all wire is called Romex.


still wrong though. UF cable is also limited to 60c

 

[qdeathstar]

Copper UF-B | Southwire

Keep your outdoor electrical projects safe and reliable with Southwire's copper UF-B cable. Our cables are sunlight, moisture, and fungus resistant.

www.southwire.com

 

[rwiegand]

You are correct. I don't seem to be able to delete the incorrect information in my previous posts.

That's what I get for believing an electrician and our town inspector-- I did actually ask the specific question!

 

[Jeremy3292]

You are correct. I don't seem to be able to delete the incorrect information in my previous posts.

That's what I get for believing an electrician and our town inspector-- I did actually ask the specific question!

No worries at all. I think @qdeathstar and others would tell you I am wrong a lot too

 

[qdeathstar]

You are correct. I don't seem to be able to delete the incorrect information in my previous posts.

That's what I get for believing an electrician and our town inspector-- I did actually ask the specific question!

That’s because the typical use for 6-2 nm cable is for an air handler/heat and it is acceptable to put 6-2nm cable on a 60 amp breaker in that case because the heat strips only draws around 42 amps…

 

[Rodney!]

I am in the middle of planning my install as well. I am going to future proof my install, and run 3awg THWN-2 directly to the wall charger, so the circuit is ready for 80 amp charging in the event I get a vehicle that can charge that rate in the future...

I too have a decent run, 70' or so, half of that going to be outside. Gonna cost $500 ish for the materials...

 

[Kasakato]

I am in the middle of planning my install as well. I am going to future proof my install, and run 3awg THWN-2 directly to the wall charger, so the circuit is ready for 80 amp charging in the event I get a vehicle that can charge that rate in the future...

I too have a decent run, 70' or so, half of that going to be outside. Gonna cost $500 ish for the materials...

Be aware the Gen3 WC only accepts up to 4AWG on its lugs. You would have to step down in a junction before the WC.

 

[Rodney!]

Thanks, but I sourced a Gen 2 charger.

I could always just trim a few strands if the three gauge doesn't fit, but I think I should be good.

 

[Jeremy3292]

Thanks, but I sourced a Gen 2 charger.

I could always just trim a few strands if the three gauge doesn't fit, but I think I should be good.

Why would you not just use 4 gauge THHN? Good for up to 95 amps...

 

[qdeathstar]

I think the trend is for chargers to be capped at around 50 amps…

 

[Rodney!]

Why would you not just use 4 gauge THHN? Good for up to 95 amps...

Well, I don't want to do the wiring 2x. The gen 2 charger can handle a 100amp circuit, so I will run 100amp wire. The cost difference between 3 awg vs 4awg is nominal. If/when I need a larger circuit then 60amp, all I will have to do is swap the breaker and change the settings on the existing wall charger or replace wall charger. Easy peasy...

I think the trend is for chargers to be capped at around 50 amps…

Well, not sure if you are referring to input or output. The current generation 3.5 Tesla wall charger maxes out at a 48amp output, which needs a 60amp circuit.

Who knows what is coming in the future. Word has it the Ford Lightening charges at an 80amp rate, so my 3awg 100amp circuit will be able to handle that. Or, perhaps I get another Tesla, I then can daisy chain the chargers. Older Model S charged at a higher rate, so who knows if they will go back to that.