50A NEMA on 60A SubPanel

[PCARs]

@PCARs
Since it likely is a long run from the main panel, I recommend using a hard wired EVSE, like Tesla's wall connector. That saves the cost of an unused neutral wire, needed for 14-50 and 14-30 outlets. It also saves the cost of a GFCI breaker, allowing a normal breaker to be used.

GSP

good call out. I'll investigate that more. My thought was a wall charger doesn't add much value to the 3RWD over the mobile charger on a 50A circuit, but if installation is cheaper, then maybe is worth it to go straight for that.

 

[PCARs]

My house looks similar. I have a main panel with AC units (3), dryer, ovens (2), and then two sub panels each on 60a to run everything else (a crap ton of 15 & 20a breakers).

My electrician put the HPWC on the main panel.

I would run it back to the main or consider 30a outlet off the sub panel.

In your case, the car will not exceed 32a, but I’m worried your setting up your future you for problems if you get something that can pull more.

How much is the quote to take it from the subpanel? You said $1k more from the main.

Is it going to be inspected?

Its about $500 vs $1450. No permits or inspections are supposedly required where I live (not in a city limit). The installer mentioned Tesla needs to "sign off on it" though?

Main panel is on the opposite side of the house, so an attic run is required for an independent circuit. I'm also worried about future upgrades as well if I get a car that can draw more than 32a.

 

[GSP]

The electrician who quoted this did include an estimated load analysis of 59A on the 60A circuit. Seems very "convenient" to be right under the max load. I don't know if this is truly accurate or are just trying to show a lower price to get the job and then say they need to do an attic run on an independent circuit at 3X the cost?

Sounds really fishy to me! While I recommend having a professional do the load calc, it may pay to do one yourself to check for reasonableness. I don't see how a new 50 A breaker, plus all of the existing breakers, can be OK with a 60 A panel.

There are lots of load calc tools on the web. Probably out of date or not applicable to your locality, but good for a rough double check. Here is a spreadsheet that comes up in a google search:

Residential Load Calculation Worksheet | The City of Naperville

The residential load calculation worksheet calculates the minimum size electrical service for a new or existing dwelling looking to add additional electrical load.

www.naperville.il.us

Good Luck,

GSP

 

[GSP]

good call out. I'll investigate that more. My thought was a wall charger doesn't add much value to the 3RWD over the mobile charger on a 50A circuit, but if installation is cheaper, then maybe is worth it to go straight for that.

There are threads here that discuss Wall Connector vs. Plug + Mobile Connector. I will look for one. Bottom line is that wall connector is recommended due to extra cost GFCI breakers now being required for 240 V outlets used for EV charging. Maybe your area doesn't have this new requirement yet, but I still recommend a wall connector.

If you do decide to stick with the mobile connector, a 6-50 outlet doesn't have the unneeded neutral wire that a 14-50 outlet requires. You would have to buy Tesla's 6-50 mobile adapter, but it should save money overall.

Wall charger on 60 A circuit is most future proof, if you plan to stay in your home and have multiple EVs someday, but 40 A circuit or even 30 A is sufficient for overnight charging (unless you have very short off-peak hours for your electricity). IIRC, a 40 A circuit gives the fastest charging for the cost of a lengthy wire run, compared to 30, 50, or 60 Amp wiring.

GSP

Edit: link to a wall connector vs. mobile connector thread:

Installing Wall Connector is better than NEMA 14-50

I bought a new Model Y recently and was planning to install NEMA 14-50 Receptacle for the Mobile charger. I saw many posts and youtube videos regarding this. Now, it looks like a wall connector is the best option to install. For Installing NEMA Outlet for Mobile Charger - I have to buy NEMA...

teslamotorsclub.com

There is a lot of talk about using 14-50 with the mobile connector, but I would definitely go with 6-50 for a long wire run.

 

[Unclepaul]

If your breaker trips, you can always turn down the average your car will draw from your display.

Usually no need to draw the full possible amperage.

May take a little longer to charge, but you might sleep better as well.

 

[PCARs]

Your car can charge at a maximum of 32 amps. As such, I would install a 40 amp circuit breaker on that NEMA 14-50 receptacle (code allows that). Make sure it’s a Hubbell or Bryant brand (there’s a third that I don’t remember the name of) - NOT a Leviton, which are known for melting and arcing.

I would also do the extra work to power it from the main panel, not the sub panel. Your sub panel already appears to be doing most of the heavy lifting - perhaps more than it should be.

That said, if you’re going through the effort of running to the main panel, I’d do a hard wired install on a 60 amp circuit. Future proof and done correctly.

Do you think a 40 or even 30a NEMA would still be too much on the subpanel though?

 

[GSP]

@PCARs

Here is a good post that sums up the wall connector vs. mobile connector costs. Shorter to read than the dozens of pages I linked above:

Installing Wall Charger vs Mobile Connector

Product price aside...Is it the same price to run a Nema 14-50 Outlet vs. Hardwire the Wall connector...Have no line like this in garage so am curious to know if the only reason to not due the wall connector is because of the $200 difference (approx) in product...Is the electrician labor...

teslamotorsclub.com

GSP

 

[PCARs]

@PCARs

Here is a good post that sums up the wall connector vs. mobile connector costs. Shorter to read than the dozens of pages I linked above:

Installing Wall Charger vs Mobile Connector

Product price aside...Is it the same price to run a Nema 14-50 Outlet vs. Hardwire the Wall connector...Have no line like this in garage so am curious to know if the only reason to not due the wall connector is because of the $200 difference (approx) in product...Is the electrician labor...

teslamotorsclub.com

GSP

Thanks for all the insights. I'l do a calculation myself to confirm and look through the articles above!

 

[Sophias_dad]

I'd be popping the cover off the subpanel to see what the feed wire is. Maybe the electrician could increase the feed breaker somewhat to get you a little more power.

That 60A panel definitely can't take a 50A(40A continuous) additional load. The refrigerator alone is likely to take significant power from one of the legs for a while at a time(defrost cycle), and with almost anything else running or turned on the feed breaker will trip.

The electrician isn't allowed to design for the actual continuous load when considering a 50A(40A continuous) load. The 50A should count as 50A of your 60A, and he's apparently telling you that the combination of ALL those other outlets will never exceed 9A for any significant time. (ya, those are all 120V legs, so if you pick wisely you could find TWO breakers and run them to 9A each while charging and it won't trip anything)

 

[Sophias_dad]

Another idea if you have a little time for data collection is to install a clamp-on energy monitor on the feed legs of the subpanel and see what the actual loads look like over time(days or weeks, or even SEASONS, given that the furnace is on that panel).

Technically you aren't even allowed to use such experimentation in determining whether more load can be put on the panel anyway.

 

[brkaus]

Personally, I’d pull the line for the extra capacity. As others have said, you can get by without the neutral if you out in a 6-50 (or a wall connector). Note wire sizing as well, if you want to future proof I’d check price to use appropriate sized wire in MC cable to eventually support 60a (48a charging).

Never heard that “Tesla needs to sign off”. Sounds fishy.

Your right that some areas do not need an inspection.

 

[Rocky_H]

My thought was a wall charger doesn't add much value to the 3RWD over the mobile charger on a 50A circuit,

But having to use a GFCI breaker is expensive and more troublesome, so there is value in not having to use it.

I'm also worried about future upgrades as well if I get a car that can draw more than 32a.

But that's not really relevant. You're saying that as if a car with a bigger onboard charger simply can't charge using that 32A, but that's not true. You can still use that same 32A just fine. And getting a car with a bigger onboard charger doesn't make your house twice as far from work and have to charge more or faster.

That is a lot of breakers in the 60 A subpanel! I wonder what the electrician's load calculation looks like. I am not an electrician, but I would guess it is close to being overloaded already. I recommend getting an electrician that will do the load calculation and show it to you, or maybe try to do it yourself with an on-line calculator.

Oh yeah. I am fascinated to see what a load calculation looks on that right now. It looks close as it is, without adding anything.

 

[PCARs]

But having to use a GFCI breaker is expensive and more troublesome, so there is value in not having to use it.

But that's not really relevant. You're saying that as if a car with a bigger onboard charger simply can't charge using that 32A, but that's not true. You can still use that same 32A just fine. And getting a car with a bigger onboard charger doesn't make your house twice as far from work and have to charge more or faster.


Oh yeah. I am fascinated to see what a load calculation looks on that right now. It looks close as it is, without adding anything.

I was not aware of the extra expense for a GFCI breaker, so will need to look into that.

As for upgrading, it was more saying I would want to be able to charge at closer to the maximum over where the RWD's current limitation is.

The electrician's load calculation was 59a WITH 40A draw on the 50a NEMA outlet. That seemed strange to me and is really what inclined me to start this thread.

Great insights from everyone so far!

 

[Rocky_H]

I was not aware of the extra expense for a GFCI breaker, so will need to look into that.

Yeah, it's kind of crazy. It's almost a hundred dollars more for the GFCI versions of these breakers.

 

[Whatstreet]

It would be best to pull a line for a dedicated circuit from the main panel. Even better, get a quote for two dedicated circuits from the main panel if there is a chance you might get a second EV. The cost for materials scales with the additional circuit but the labor cost may not be that much different.

 

[Whatstreet]

I was not aware of the extra expense for a GFCI breaker, so will need to look into that.

Tesla wall connector has built in GFCI and so breaker with GFCI is not recommended.

 

[Rocky_H]

Tesla wall connector has built in GFCI and so breaker with GFCI is not recommended.

Well, the mobile charging cord has built-in GFCI too, so that's not the reason for that distinction. It's just that hard wired devices have all of the wire connections closed up inside where a person isn't going to be touching them. A device that can plug into an outlet has that exposure risk where a person's finger could slip and touch a hot prong while plugging or unplugging.

 

[Whatstreet]

You are contradicting the manual which you quote as gospel for its recommendation for a subpanel for power sharing. Do you follow the manual or not? Make up your mind.

 

[Rocky_H]

You are contradicting the manual which you quote as gospel for its recommendation for a subpanel for power sharing. Do you follow the manual or not? Make up your mind.

I did not contradict the manual in any way whatsoever. Please give a citation of where you think I did so.

"Wall connector includes integrated GFCI protection"

Yes, it does. So does the mobile connector.

"do not install a GFCI circuit breaker"

Right, but with the mobile connector, which also includes that integrated GFCI protection, you DO have to install a GFCI breaker. So my point was that the integrated GFCI in the unit is NOT the reason why there is the breaker difference, because they both have that same feature.

 

[colepalmer]

I would advise you to get a good master electrician that you trust and have him/her give you advice. My house at 200 amps was loaded when I added two 15k BTU heat pumps. Solution, new 100 amp sub-panel. 60 amp circuit breaker is perfect for the 48 amps I use. It runs from a new meter which has the circuit breaker. The whole house runs through this new meter box. Do yourself a favor and do it right.