Need assistance on installing Tesla Wall charger ver 3

[canbonbon]

Not stated or implied that you could use 6 gauge NM-B (Romex) for a circuit greater than 55 amps. I was pointing out that the wire used in NM-B is THHN rated for 90C temperature. For 6 gauge NM-B the maximum rated circuit amperage is 55 amps. This limitation is due to the way the NM-B cable is constructed. Following the 80% rule, 55 amp maximum you could use 6 gauge NM-B for a circuit for EV charging at up to 44 amps. This amperage setting limit is unavailable on Tesla Wall Connector, only supports ... 32/40/48 amps. If you use 6 gauge NM-B and a 50 amp circuit breaker you can set the Wall Connector for 40 amps but not 48 amps.

Metallic clad (MC) cable has a flexible (but not waterproof) metal sheath surrounding, protecting the individual wires. In dry locations, indoors MC eliminates the need for conduit. MC cable uses 90C rated THHN wire. Because there is ample space around each conductor for airflow and cooling the maximum amperage of 6 gauge MC is higher than NM-B, can be used with circuits rated for up to 75 amps.

Thanks, then MC would work great for us. It will travel along with the basement ceiling (dry location) and we should be able to get 48 Amps at the charger.

 

[zoomer0056]

Are you saying we can use #6/2 Romex for 48 Amp draw?

You can not use romex. Use #6 THHN for the hot wires and #8 for the other. It will fit in the conduit. It, from my pick, is 3/4" metal conduit. Its been awhile but that 3/4" must be inside diameter.

 

[jcanoe]

Thanks, then MC would work great for us. It will travel along with the basement ceiling (dry location) and we should be able to get 48 Amps at the charger.

Working With Metal-Clad (MC) Cable

 

[Sami123]

@jcanoe, it sounds like using a 6/2 MC cable - expensive as it may be - will allow us to install a code compliant 60A circuit? I got quotes from two Tesla recommended electricians, and they both ended up recommending 6/2 Romex (at least in the basement run) which from everything I read on this board, is 55A and not 60A code compliant. I want to recommend to them using the 6/2 MC instead and get them to adjust their installation quote accordingly.
Thanks!

 

[canbonbon]

@jcanoe, it sounds like using a 6/2 MC cable - expensive as it may be - will allow us to install a code compliant 60A circuit? I got quotes from two Tesla recommended electricians, and they both ended up recommending 6/2 Romex (at least in the basement run) which from everything I read on this board, is 55A and not 60A code compliant. I want to recommend to them using the 6/2 MC instead and get them to adjust their installation quote accordingly.
Thanks!

For MC being expensive, just wanted to let you know that somehow my electrician was able to find #6/2 MC for a very similar price as Romex #6/2. So I would recommend calling local Electrical supply stores and get prices. As per my electrician, MC is used mostly in commercial buildings where the have steel studs and have to pull the wire through them and a standard Romex would get ripped while going through them. That is why its difficult to find various versions of MCs at HomeDepot or Lowes (which mostly carry residential stuff) and you'd need to go to electrical Supply store for a #6/2MC.

 

[jcanoe]

For MC being expensive, just wanted to let you know that somehow my electrician was able to find #6/2 MC for a very similar price as Romex #6/2. So I would recommend calling local Electrical supply stores and get prices. As per my electrician, MC is used mostly in commercial buildings where the have steel studs and have to pull the wire through them and a standard Romex would get ripped while going through them. That is why its difficult to find various versions of MCs at HomeDepot or Lowes (which mostly carry residential stuff) and you'd need to go to electrical Supply store for a #6/2MC.

You can purchase MC cable on Amazon in different lengths, gauges and wire configurations. A licensed electrician may use an electrical supply house due to a business relationship and may receive a discount.

In 2016 I hired a master electrician to install a 240V/50 amp circuit and a 14-50 receptacle in my garage, permit etc. Right up to the point when the electrician was scheduled to perform the work he was undecided as to how he would run the wire for the new circuit. In the end he decided to go from the basement where the sub panel is located up into the attic instead running conduit outside of the house, then into the attic and into the garage. The electrician knew from experience he could guide the MC cable up into the attic using the preexisting penetrations for the plumbing vent stack. The electrician purchased the needed ~70 feet of MC wire the same day or the day before he installed the circuit. I never asked the electrician about the wire gauge but based on the outer diameter of the aluminum casing of the MC wire (~0.76 inch) I have concluded that this is 8/3 THHN, rated for up to 55 amps. (At the time I specified I wanted a 50 amp circuit, not 60 amps as I had no experience with the Tesla home charging station options.) This work cost me ~$1700 including the permit. The cost probably would have been more if the electrician had used conduit.

 

[canbonbon]

Tesla connector installed. Finally. Thanks for everyone's help on this board. Got some valuable suggestions which helped me make right decisions. Here is the final summary:

90 ft run. Used #6/2 MC cable with a 60 Amp breaker. Wall Connector is set to 48Amp.
Connecter was installed in the center of the garage so that it can reach all three bays. The wire was fished from garage to a lower level basement ceiling and then a straight run to the panel along the central LVLs held up by 3/4" single hole straps. Terminated in the box with a 60 AMP breaker. The entire setup works great. Inspection sometime next week but should be fine. Very clean work.

 

[zoomer0056]

Tesla connector installed. Finally. Thanks for everyone's help on this board. Got some valuable suggestions which helped me make right suggestions. Here is the final summary:

90 ft run. Used #6/2 MC cable with a 60 Amp breaker. Wall Connector is set to 48Amp.
Connecter was installed in the center of the garage so that it can reach all three bays. The wire was fished from garage to a lower level basement ceiling and then a straight run to the panel along the central LVLs held up by 3/4" single hole straps. Terminated in the box with a 60 AMP breaker. The entire setup works great. Inspection sometime next week but should be fine. Very clean work.

Great , happy charging. What brand of breaker did you use?

 

[canbonbon]

Great , happy charging. What brand of breaker did you use?

My panel takes SquareD so got it from homedepot for $15.

 

[Mrbrock]

Disagree on Romex. I used THHN as you mentioned in your original post.

I ended up purchasing black color conductor from Lowes and red color conductor online. Different colors for the two hot conductors make life easier for cable management.
#4 AWG THHN wire for conductors (one black, one red)
#6 or #8 AWG THHN wire for ground (green). Check code.
60a breaker
48a continuous load
Put all wires in conduit like PVC Schedule 80. Check code--I think 2 inch conduit is required
With this config, keep the wire length under approx 80-100 feet (check online for voltage drop, etc. to get accurate max conductor length).
Lugs for the conductor termination into the Tesla wall unit
*** make sure panel is not hot so you don't get fried ***

Save receipts and file IRS 8911 "Alternative Fuel Vehicle Refueling Property Credit" to claim tax credit.

2" Sch80 PVC allows up to 14 4ga conductors. Way overkill.

Clearly #4 THHN is better choice but the real issue for me is the conduit. I cannot put a 2" conduit on the basement ceiling along with other wires. I mean it can be done but it will be a lot of labor to get what? Just 8 more amps? I think I might stick with #6/2 Romex (much easier to install) and reduce the charging to 40 Amp instead. Not the end of the world because even at 40 Amp we would get like 300 miles in 8 hours. We don't drive 300 miles per day so should not be an issue.

I know you ended up with MC cable but you didn't need 2" conduit. For 4ga, you'd need 1" PVC/1" EMT/3/4" IMC. For 6ga, 3/4" any material would get you at least 3 conductors. 6ga THHN in 3/4" sch40 PVC is easy to work with, inexpensive, easy to install, paint, etc.

 

[canbonbon]

2" Sch80 PVC allows up to 14 4ga conductors. Way overkill.


I know you ended up with MC cable but you didn't need 2" conduit. For 4ga, you'd need 1" PVC/1" EMT/3/4" IMC. For 6ga, 3/4" any material would get you at least 3 conductors. 6ga THHN in 3/4" sch40 PVC is easy to work with, inexpensive, easy to install, paint, etc.

Wanted to clarify that putting any conduit (regardless of size) was a challenge for us. Also, I think it was a typo my part. I meant to say 1" inch but accidently wrote 2". But in the end MC worked out great for us. Thanks for clarifying the sizing, it might help others who might be doing a conduit.

 

[Mrbrock]

Wanted to clarify that putting any conduit (regardless of size) was a challenge for us. Also, I think it was a typo my part. I meant to say 1" inch but accidently wrote 2". But in the end MC worked out great for us. Thanks for clarifying the sizing, it might help others who might be doing a conduit.

Ok. If you have to run through joists then MC is easier. As would running 50A on 6ga NMB. If you can attach to bottom of joists or run in between joists, conduit is quite simple and you can pull the wires as you go instead of trying to go from start to finish. Glad you found a good solution.

 

[mgberry]

Your electricians need some retraining. They don't realize that the continuous usage of an EV mandates that the wire and breaker be oversized by 25% for a given load.

As to whether 6-2(6-3 is overkill and completely unnecessary for an HPWC) will support 48 amps, it will, and would be within the rules in Canada. But you aren't in Canada, and if your house happens to burn down your insurance will probably tell you to go screw. I myself am running 48 amps through 6-2 NMB that's in my 60F basement for its entire run, which allows me, even within the extremely conservative rules of the NEC, to run like 47.5 amps through it continuously.

My electrician is using #6 wire as well. Not all 6 gauge is the same. The 6 gauge he is using is actually rated for 75 amp. Since there is a max amp of 48 you times that by 1.25 to compensate for continuous duty load, etc....

 

[Sophias_dad]

My electrician is using #6 wire as well. Not all 6 gauge is the same. The 6 gauge he is using is actually rated for 75 amp. Since there is a max amp of 48 you times that by 1.25 to compensate for continuous duty load, etc....

Thanks, but no. First thing is that there is NO #6 that can be used for 75 amps in a residential setting. You simply aren't ever allowed to use the 90C rating for conductors like this, because the terminations(breaker and HPWC lugs) aren't rated for 90C.

The second thing is that NM cable is required to be used at the 60C rating, or 55 amps. I'm too lazy to look up the NEC section saying this. 48 times 1.25 is 60, and that's more than 55.

Don't get me wrong, I'm using #6 NM cable for 48 amps just fine, but I realize this and accept the risk. It sounds like your electrician does too.

 

[Art84]

#6 THHN cable installed in conduit can be used (and to the code) in residential installations for 48A setup. #6 NM - is not. Period.

 

[mgberry]

#6 THHN cable installed in conduit can be used (and to the code) in residential installations for 48A setup. #6 NM - is not. Period.

Correct. NM should never be used, he said as well. He is installing now and I asked about the #4 vs #6. The #6 THHN cable in PVC conduit meets the requirements for a 60 amp circuit giving the maximum pull of the wall charger with continues duty factored in. I have to believe certified electricians know what they are doing.

 

[Sophias_dad]

Correct. NM should never be used, he said as well. He is installing now and I asked about the #4 vs #6. The #6 THHN cable in PVC conduit meets the requirements for a 60 amp circuit giving the maximum pull of the wall charger with continues duty factored in. I have to believe certified electricians know what they are doing.

He's correct, #6 in conduit is fine for a 60 amp circuit. I'm not really sure why you made post #53, since its fairly misleading. Why even resurrect this thread from its three month slumber?

 

[mgberry]

He's correct, #6 in conduit is fine for a 60 amp circuit. I'm not really sure why you made post #53, since its fairly misleading. Why even resurrect this thread from its three month slumber?

Didn't mean to cause Maham Just see a lot of people saying you have to use #4 gauge with a 60 amp.

 

[Mrbrock]

Didn't mean to cause Maham Just see a lot of people saying you have to use #4 gauge with a 60 amp.

4 NMB yes, 6 THHN yes. 6NMB no. 6 MC yes. You have to be specific. About which type of wiring. Since NMB is cheapest, doesn’t require conduit in walls or garages amd is easiest to use as a one piece solution, that is what most people talk about when they refer to 6ga wire.

 

[Junkfoodz]

6-2 from Lowes are Home Depot is fine...