Breaker Box Advice

[fholbert]

But that 50A pool breaker may bring you over a 200A service limit.

My pool put me right at the limit. Simple solution, pool shuts off at 9:00pm, Tesla starts charging at midnight. I should also say I have a multi speed pool pump which uses very little power other that startup/prime which lasts about 3 minutes. The Tesla is fully charged long before the pool starts up.

We don't currently use our dryer 240 volt which is in the utility room because we have a gas dryer that users a regular 110 plug to power it.

Nothing says you can't charge at 240v 30a (dryer breaker). I have a friend who's charged a MY for a year with 120v 20a, that meets his needs. How many miles a day do you drive?

 

[Stack24]

My pool put me right at the limit. Simple solution, pool shuts off at 9:00pm, Tesla starts charging at midnight. I should also say I have a multi speed pool pump which uses very little power other that startup/prime which lasts about 3 minutes. The Tesla is fully charged long before the pool starts up.

Nothing says you can't charge at 240v 30a (dryer breaker). I have a friend who's charged a MY for a year with 120v 20a, that meets his needs. How many miles a day do you drive?

Yeah we have a variable speed pump setup as well. It is on from 8AM to 8PM but running at very low power. So it wouldn't be drawing at the same time like your setup.

That looks like an awesome scope of work. Nice that they spec'd EMT, which is appropriate for a garage (where damage can occur). I'd go with those guys!

Yeah the PDF document they sent was like 11 pages long and they did mockups and detailed quotes. I did like how thorough they were. The price wasn't bad either. $681 for the install including a run of 15 Feet to the location I want.

 

[jjrandorin]

BTW I accidentally posted in the Model 3 but I ordered a Model Y. But not sure that makes a difference and can help others.

(moderator note)

For the purposes of this discussion, whether its a model 3 or Y doesnt really matter. I think its fine where it is (the thread), but if you want me to move it to the model 3 subform I can do that too.

 

[bruce4000]

As a data point, my 45 year old breaker panel needed replacing so I went ahead and got a TWC and they put it on a 50 amp 240v dedicated circuit as I had plenty of room. While the TWC supports living on up to a 60 amp breaker, it can be configured all the way down to 15 amp. I found that if I set the car charger rate to 31 Amps (can go up to 40 amps with 50 amp breaker), it charges 10% an hour for my MY.

 

[Rocky_H]

Wow, that's a very detailed job description. I noticed they also included a 20A twin breaker, so that shows where they are combining two to free up the extra space, and good to see they're using 6 gauge THHN wire in conduit for the 60A circuit, so it's not doing that common mistake of 6 gauge NM-B for it.

 

[jjrandorin]

Wow, that's a very detailed job description. I noticed they also included a 20A twin breaker, so that shows where they are combining two to free up the extra space, and good to see they're using 6 gauge THHN wire in conduit for the 60A circuit, so it's not doing that common mistake of 6 gauge NM-B for it.

I thought the same thing. I looked at that and felt the same as @Cosmacelf said, which is "wow, look at that... I would hire them for my own home just based on how detailed that quote is."

 

[Stack24]

Second company is out now and working on the quote. Question for the group.

This company said since I have a 1 story and attic access it's cheaper for him to just run the cables in the attic to the location I want. Is there any benefit for me to do it with conduit in the garage? If not I will probably ask the first company with the detailed quote to price it out going through the attic instead of conduit.

Conduit setup would use THNN while he said Attic they would use SER cable. (Second Electrical company)

 

[Rocky_H]

Second company is out now and working on the quote. Question for the group.

This company said since I have a 1 story and attic access it's cheaper for him to just run the cables in the attic to the location I want. Is there any benefit for me to do it with conduit in the garage? If not I will probably ask the first company with the detailed quote to price it out going through the attic instead of conduit.

No, nothing wrong with doing that on its face, buuuuuut I have a specific suspicion about this. What type of wire method is used is mostly determined by where it is going. If it's along the exposed surface of walls, you generally need to use wires in conduit. But for things like inside insulated sheetrock walls or up in attics is what NM-B cable (Romex) is meant for. So sure, using cable in the attic would be quicker/easier of an install than having to cut and mount conduit.

That is a proper use of Romex cable, but it gets into the potential problem I mentioned before. 6 gauge Romex only has a 55A rating, so it IS NOT acceptable for a 60A circuit, and for some strange reason way too many electricians try to use it for that. So for code compliance, this would have to upside to 4 gauge Romex, which costs quite a bit more.

So labor time/cost would be less and wire cost would be more. It depends which is a more sizeable shift on the price quote. I have this sneaking suspicion that they are thinking 6 gauge Romex (which is wrong and cheap) and also saving the labor cost.

 

[Stack24]

No, nothing wrong with doing that on its face, buuuuuut I have a specific suspicion about this. What type of wire method is used is mostly determined by where it is going. If it's along the exposed surface of walls, you generally need to use wires in conduit. But for things like inside insulated sheetrock walls or up in attics is what NM-B cable (Romex) is meant for. So sure, using cable in the attic would be quicker/easier of an install than having to cut and mount conduit.

That is a proper use of Romex cable, but it gets into the potential problem I mentioned before. 6 gauge Romex only has a 55A rating, so it IS NOT acceptable for a 60A circuit, and for some strange reason way too many electricians try to use it for that. So for code compliance, this would have to upside to 4 gauge Romex, which costs quite a bit more.

So labor time/cost would be less and wire cost would be more. It depends which is a more sizeable shift on the price quote. I have this sneaking suspicion that they are thinking 6 gauge Romex (which is wrong and cheap) and also saving the labor cost.

Thank you for your analysis and detailed feedback. The wall that they would be installing it is drywall that is the garage wall that would be an outside wall of our house. Same inside the garage wall our panel is. On the quote they gave us they say 6 AWG SER cable concealed inside wall.

I called the original company and asked them about running it in the attic becuase I do like how detailed their quote is etc. They said it wouldn't be much of a difference maybe a little more because a bit more cable run to go up and down. They would use a Flex Metal conduit and the same THNN cable. So I guess it comes down to if I care that there would be conduit or would I want a clean look.

I feel like saving money always wins lol.

 

[Rocky_H]

On the quote they gave us they say 6 AWG SER cable concealed inside wall.

That is exactly what I was worried about!! That violates the ampacity rating, and is a code violation.

SER Cable Temperature Rating

www.electriciantalk.com

"Interior Installations. In addition to the provisions
of this article, Type SE service-entrance cable used for interior
wiring shall comply with the installation requirements
of Part II of Article 334, excluding 334.80.
Where installed in thermal insulation, the ampacity shall
be in accordance with the 60°C (140°F) conductor temperature
rating. The maximum conductor temperature rating
shall be permitted to be used for ampacity adjustment and
correction purposes, if the final derated ampacity does not
exceed that for a 60°C (140°F) rated conductor."

That is from NEC. It says if SER cable is being installed in insulation (which inside a sheetrock wall would be) then it has to use the 60 degrees C amp rating, which is the same as Romex. And that is only 55A for 6 gauge. So that can't be used for a 60A rated circuit. This would have to upsize to 4 gauge.

This is the same Romex rating mistake we see way too frequently on these forums!

I feel like saving money always wins lol.

I feel like complying with code should be condition #1 and then saving money can be condition #2. Since this doesn't meet condition #1, I wouldn't do it.

 

[Cosmacelf]

Yeah the PDF document they sent was like 11 pages long and they did mockups and detailed quotes. I did like how thorough they were. The price wasn't bad either. $681 for the install including a run of 15 Feet to the location I want.

That's a good price for an EMT install.

 

[davewill]

That is from NEC. It says if SER cable is being installed in insulation (which inside a sheetrock wall would be) then it has to use the 60 degrees C amp rating, which is the same as Romex. And that is only 55A for 6 gauge. So that can't be used for a 60A rated circuit. This would have to upsize to 4 gauge.

Inside the wall probably wouldn't be insulated if it is an interior wall. Personally, I would just do (and did) conduit on the wall.

 

[Stack24]

Inside the wall probably wouldn't be insulated if it is an interior wall. Personally, I would just do (and did) conduit on the wall.

The wall is an exterior wall but it's the garage. I need to look back at my pictures from construction to see if those are insulated but I don't think they are since it is the garage.

I think I am going to go the conduit route whoever does give me quote.

 

[Rocky_H]

The wall is an exterior wall but it's the garage. I need to look back at my pictures from construction to see if those are insulated but I don't think they are since it is the garage.

I don't know construction techniques intimately well, but for an attached garage, I would bet pretty heavily that those exterior walls are still insulation filled. The garage isn't a conditioned air space, but since it is attached to the house, there is interest in keeping it somewhat insulated so it doesn't go extremely chilled which would suck energy from the attached house. It acts a bit like a buffer zone. The inside of my garage almost never goes below freezing point, and I would think there is some insulation in the walls that helps that happen.

 

[ewoodrick]

I don't know construction techniques intimately well, but for an attached garage, I would bet pretty heavily that those exterior walls are still insulation filled. The garage isn't a conditioned air space, but since it is attached to the house, there is interest in keeping it somewhat insulated so it doesn't go extremely chilled which would suck energy from the attached house. It acts a bit like a buffer zone. The inside of my garage almost never goes below freezing point, and I would think there is some insulation in the walls that helps that happen.

The exterior garage walls wouldn't be, but the walls that border the garage from the inside would be.

And the one thing that most people don't notice, is the garage door even insulated, many aren't

 

[Stack24]

That is exactly what I was worried about!! That violates the ampacity rating, and is a code violation.

SER Cable Temperature Rating

www.electriciantalk.com

"Interior Installations. In addition to the provisions
of this article, Type SE service-entrance cable used for interior
wiring shall comply with the installation requirements
of Part II of Article 334, excluding 334.80.
Where installed in thermal insulation, the ampacity shall
be in accordance with the 60°C (140°F) conductor temperature
rating. The maximum conductor temperature rating
shall be permitted to be used for ampacity adjustment and
correction purposes, if the final derated ampacity does not
exceed that for a 60°C (140°F) rated conductor."

That is from NEC. It says if SER cable is being installed in insulation (which inside a sheetrock wall would be) then it has to use the 60 degrees C amp rating, which is the same as Romex. And that is only 55A for 6 gauge. So that can't be used for a 60A rated circuit. This would have to upsize to 4 gauge.

This is the same Romex rating mistake we see way too frequently on these forums!


I feel like complying with code should be condition #1 and then saving money can be condition #2. Since this doesn't meet condition #1, I wouldn't do it

So I reached out to the company which is very highly recommends from friends and online and this was his response when I asked him if he could explain all of it and let me know. Btw my area does have codes or permits at the moment.

This info is from their Master Electrician.

Would love to hear thoughts since I know this info could valuable for others.

According to our interpretation of NEC, 6 AWG SER copper cable is a high temperature insulated wire and will never have the same temperature rating of romex no matter the application. It is the same insulation as THWN/THHN dual rated wire, which is what we would put inside conduit.

The presence or lack of insulation in a drywall wall has no effect on the SER cable and in fact SER cable is rated and designed to commonly be used in attics with the ambient temperature which exceed 65 Celsius. 6 AWG SER cable is rated for max of 75 amps, while the 6 AWG stranded wire is rated for 65 amps. In either case, both wires are adequate for the Tesla charger which has a maximum current draw of 48 amps (on a 60 amp breaker).

Either option of surface mounted conduit with 6 awg THHN wire, or in-wall concealed 6 awg SER, can certainly handle the maximum draw of the Tesla Gen 3 wall connector without any issues or danger.

We use both methods at equal frequency in our installations, which have been successfully permitted and inspected and found to be up to code, by city of Houston inspectors for years.

 

[DuncanM]

Of course you could just use a 50amp breaker and then charge at 40amps.

 

[Stack24]

Of course you could just use a 50amp breaker and then charge at 40amps.

I saw this solution earlier. Curious if they are actually using copper as he stated which is rated higher and is saying doesn't that mean I could run the 60AMP?

 

[DuncanM]

I saw this solution earlier. Curious if they are actually using copper as he stated which is rated higher and is saying doesn't that mean I could run the 60AMP?

I can't comment on the wire specs and the max allowed amperage except that in practical terms there's not much difference in charging times between 40 and 48 amps. If you are getting a RWD MY then you're limited to 32 amps anyways,

 

[Rocky_H]

So I see that the response from the electrician flat-out avoids this direct question.

According to our interpretation of NEC, 6 AWG SER copper cable is a high temperature insulated wire and will never have the same temperature rating of romex no matter the application.

That directly conflicts with this line from NEC:

Where installed in thermal insulation, the ampacity shall
be in accordance with the 60°C (140°F) conductor temperature
rating.

It is the same insulation as THWN/THHN dual rated wire, which is what we would put inside conduit.

Yes, of course it does, and it's exactly the same THWN/THHN insulation that is on the interior wires of Romex, too! That's not the point. It's that bundled together tightly sheath situation that makes it different than wires sitting loosely in a conduit.

The presence or lack of insulation in a drywall wall has no effect on the SER cable

That is exactly the opposite of what that NEC citation says.

The response is what it is, and it shows me what I would want to find out, and that they don't want to learn. I wouldn't use them.