# EV sub-panel neutral size (no ulnbalanced load)



## HackWork (Oct 2, 2009)

Copper is very expensive right now. I would just run aluminum for the sub feeder and run a neutral as well. You will pocket a lot of cash even after running a full size neutral.


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## telsa (May 22, 2015)

Reducing the size of a neutral can be justified if the 240VAC loads are built-in... nothing will change until another electrician steps up.

You can't have that assurance with plugged in loads. What happens when the next EV is designed for 120VAC charging? ( BTW, every EV I've read of has this as a back-up charging solution when the primary 240VAC is not working// available. )

You either have no neutral or a full sized neutral.

Go with (3) XHHW and aluminum -- and (1) THWN copper grounding run.

It's not your role to value engineer Tesla chargers -- which are today's Duesenberg -- status symbols.

Make the panel installation a status symbol, too.


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## mikewillnot (Apr 2, 2013)

telsa said:


> You can't have that assurance with plugged in loads. What happens when the next EV is designed for 120VAC charging? ( BTW, every EV I've read of has this as a back-up charging solution when the primary 240VAC is not working// available. )
> 
> You either have no neutral or a full sized neutral.


Understood. But... it seems highly unlikely that the unbalanced load in this scenario, with a 100-amp subpanel, could ever reach 65 amps, which a #6 neutral would handle.

[edit] I'm thinking about either a 4-space or a 6-space sub.


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## mikewillnot (Apr 2, 2013)

HackWork said:


> Copper is very expensive right now. I would just run aluminum for the sub feeder and run a neutral as well. You will pocket a lot of cash even after running a full size neutral.


customer wants to configure charger #1 at 80-amp rate. Tesla specifies #3 copper for such a branch circuit. Don't see how it makes sense to put that downstream from something like #2 aluminum SER to the sub.


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## mikewillnot (Apr 2, 2013)

Actually, the subpanel was the customer's idea -- and not a bad one. If car #2 turns out to be a tesla, the chargers can be daisy chained. if not, a second branch circuit of SOME kind will be added.


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## telsa (May 22, 2015)

Your mind is in the wrong place.

You CAN'T win value-engineering in Residential.

It will bite you.

The customer is NOT hurting for money. He wants EVERYTHING first class.

Build First Class -- and Charge Large.

Then watch the client provide you with referrals.

Your current path is that of poverty.

This whole project is a JOKE compared to his outlay for the EV.


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## HackWork (Oct 2, 2009)

mikewillnot said:


> customer wants to configure charger #1 at 80-amp rate. Tesla specifies #3 copper for such a branch circuit. Don't see how it makes sense to put that downstream from something like #2 aluminum SER to the sub.


 What about when you come out of the main panel that is being fed with aluminum? You see how nonsensical that is?


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## mikewillnot (Apr 2, 2013)

HackWork said:


> What about when you come out of the main panel that is being fed with aluminum? You see how nonsensical that is?


I get your point. In this case, it's a 15kw continuous load, and a manufacturer that insists on copper, at least for the branch circuit.


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## HackWork (Oct 2, 2009)

mikewillnot said:


> I get your point. In this case, it's a 15kw continuous load, and a manufacturer that insists on copper, at least for the branch circuit.


I know, I have installed many Tesla chargers.

Use copper for the branch circuit. Use Aluminum for the subpanel feeder just like the electrical service uses as well as the entire power grid.

Tesla specifies copper for the same reason that they say to use #6 for their 50A outlet. Because they are writing it for homeowners. 

Also, I would bump up the size of that subpanel. You would want to be able to power the 80A Wall Connector along with another 40A charger since that's common.

The Wall Connector requires a 100A breaker for full 80A output, so if you install a 100A subpanel you are technically maxed out.


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## Drsparky14 (Oct 22, 2016)

HackWork said:


> Copper is very expensive right now. I would just run aluminum for the sub feeder and run a neutral as well. You will pocket a lot of cash even after running a full size neutral.




That's never a good idea. Don't be cheap just out in copper. Why do the customer a disservice by putting in aluminum wiring? 


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## HackWork (Oct 2, 2009)

Drsparky14 said:


> That's never a good idea. Don't be cheap just out in copper. Why do the customer a disservice by putting in aluminum wiring?


Aluminum for feeders is not a disservice and anyone who says that is living in the 90's and hasn't educated themselves.


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## Drsparky14 (Oct 22, 2016)

HackWork said:


> What about when you come out of the main panel that is being fed with aluminum? You see how nonsensical that is?




Why are you feeding panels with aluminum? It's such a short cut of wire and the price difference is only a few bucks if that. Instead of 4O,4O,2O aluminum just out in 3O copper x3 that way you only have to keep one size wire in the truck for residential panels. Also it's smaller AWG wire ore and easier to bend. 


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## HackWork (Oct 2, 2009)

Drsparky14 said:


> Why are you feeding panels with aluminum?


 Because they all are. The grid is all aluminum and most new services are aluminum. Subpanel feeders are mostly aluminum. 

The stigma of aluminum was about small branch circuit wiring, not feeders. And the aluminum used today is a totally different alloy as well. 




> It's such a short cut of wire and the price difference is only a few bucks if that.


 This is absolute bullsh1t. The difference is huge. Now that copper is so high the price difference on a typical service is over $200 more. 

Anyone who says "a few bucks if that" is simply clueless. I hate when people spread blatant lies that eat into another man's livelihood.


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## Drsparky14 (Oct 22, 2016)

HackWork said:


> Aluminum for feeders is not a disservice and anyone who says that is living in the 90's and hasn't educated themselves.




On the 90's aluminum was ran for way too many things. And not sure how old you are or how many years you have been doing electrical but aluminum isn't a better conductor, copper is and it doesn't need to have its connections tightened every so often. I almost never see copper feeders burn up at the lugs but I see it all the time with aluminum. I do so many panel changes and aluminum is usually always the failure point. If you have to use aluminum on your jobs to keep costs down to get the job, then do it I guess. But I always just charge accordingly and put in copper. I also use CH panels in residential unlike many others who use the cheaper BR or homeline panels. 

I get job after job after job and get great referrals on my work. I have a high quality of standards in my work and I feel proud of it at the end of the day. 


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## Drsparky14 (Oct 22, 2016)

HackWork said:


> Because they all are. The grid is all aluminum and most new services are aluminum. Subpanel feeders are mostly aluminum.
> 
> The stigma of aluminum was about small branch circuit wiring, not feeders. And the aluminum used today is a totally different alloy as well.
> 
> ...




You need to get better prices on your copper lol. 

Seriously though, copper is better. 


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## HackWork (Oct 2, 2009)

Drsparky14 said:


> You need to get better prices on your copper lol.


 I have more access to supply houses here than most people around the country. The price difference between copper and aluminum is always the same. Here is an example of a typical service change in which I use 85':

Click for bigger.








You see that? Almost $200 different. So tell me how that is "a few bucks if that" different?? 





> Seriously though, copper is better.


 No, it's not.


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## Drsparky14 (Oct 22, 2016)

HackWork said:


> I have more access to supply houses here than most people around the country. The price difference between copper and aluminum is always the same. Here is an example of a typical service change in which I use 85':
> 
> Click for bigger.
> View attachment 115121
> ...




Okay I see what you are saying on a long run. But from the meter to the panel back to back I always go copper. I can't say I never run aluminum donkey **** from the main service panel to a sub in a house. But I try to use copper where I can. I admit I was kinda trolling. Haha


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## HackWork (Oct 2, 2009)

OKee


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## frenchelectrican (Mar 15, 2007)

mikewillnot said:


> I'm setting up a sub in an attached garage for charging an EV (known specs), possibly a second EV (unknown) "down the road."
> 
> main panel 100 amp breaker ->
> #3 THHN (ungrounded), #6 THHN ground, ? neutral? ->
> ...


I am aware of Tesla chargers and for that kind of feeder IMO just not bother bring out netural for that circuit due I read the other posting and with 100 amp branch circuit . that branch circuit you will be allready maxed out if the owner of that charger have it set at max setting ( 80 ) amps.

A subpanel is a good idea but the thing is that once that customer have second charger. If that second charger is tesla model you will have to run that on seperated feeder circuit .,, I have good reason for this due what I heard but not confirmed that some owners have a way to crank it up to max and if that owner ran both chargers at same time that will raise some issue.

If the plan confirmed that the customer do have 2 tesla chargers .,, I would either really heavy up ( upgrade to 320 a) or run seperated meter for charger subpanel. 

I would run either alum or copper to the subpanel as feeder then once you branch out then flip over to copper.


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## mikewillnot (Apr 2, 2013)

HackWork said:


> Also, I would bump up the size of that subpanel. You would want to be able to power the 80A Wall Connector along with another 40A charger since that's common.


Ummmmm.... OK, I'm looking at the idea of a 150-amp sub, 2/0 SER. The main house panel is a Siemens, if I recollect. I don't see 150-amp plug-in breakers around. Actually, don't see them in ANY brand.


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## HackWork (Oct 2, 2009)

mikewillnot said:


> Ummmmm.... OK, I'm looking at the idea of a 150-amp sub, 2/0 SER. The main house panel is a Siemens, if I recollect. I don't see 150-amp plug-in breakers around. Actually, don't see them in ANY brand.


Yeah, I am starting to think running 2 #2 AL SER cables might be best. Land the first in a small disconnect for the Wall Charger and the second in one of those $17 6 space subpanels. This way they can add other things as they wish.


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## frenchelectrican (Mar 15, 2007)

mikewillnot said:


> Ummmmm.... OK, I'm looking at the idea of a 150-amp sub, 2/0 SER. The main house panel is a Siemens, if I recollect. I don't see 150-amp plug-in breakers around. Actually, don't see them in ANY brand.


The last time I have see 150 amp plug in breaker was CH series but now those are getting pretty rare.

If that customer did have 200 amp main panel in there I would not bother with it. ( 150 amp plug in breaker) 


If the customer do want subpanel in there I would just heavy up the service to 320 ( 400 amp resdentail service ) and keep the exsting 200 amp panel alone and run a new 200 amp panel for EV charger and be done with it.,, 

Because by time if you ever find that 150 amp plug in breaker and all the typical stuff .,, ya better off try tell the customer to get larger service instead see the main breaker trip off if two charger are running and what else who know run in the house .,,


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## telsa (May 22, 2015)

Plan A: Set 320A replacement Service. Charge Large.

Plan B: Bolt-on panel swap at same time. Charge Large.

And so forth.

You need to pull your mind out of Value Engineering and into Up Selling.

Your client will HATE YOU for Value Engineering this project.

I get the "willnot" in your nic.


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## mikewillnot (Apr 2, 2013)

frenchelectrican said:


> I am aware of Tesla chargers and for that kind of feeder IMO just not bother bring out netural for that circuit due I read the other posting and with 100 amp branch circuit . that branch circuit you will be allready maxed out if the owner of that charger have it set at max setting ( 80 ) amps.


My understanding of tesla's "daisy chaining" is that you essentially tie two chargers into one branch circuit, both set at the 80-amp rating. The two are interconnected by some kind of a communications connection, and they talk to each other. When two cars are charging simultaneously they both charge at 50% rate. With only one car calling for a charge, it switches to full rate.


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## HackWork (Oct 2, 2009)

mikewillnot said:


> My understanding of tesla's "daisy chaining" is that you essentially tie two chargers into one branch circuit, both set at the 80-amp rating. The two are interconnected by some kind of a communications connection, and they talk to each other. When two cars are charging simultaneously they both charge at 50% rate. With only one car calling for a charge, it switches to full rate.


This is true.

My concern is if they don't get another Tesla (which sounds like it's a possibility), then they won't have that feature and won't have the ampacity left for a typical 40A charger.


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## frenchelectrican (Mar 15, 2007)

mikewillnot said:


> My understanding of tesla's "daisy chaining" is that you essentially tie two chargers into one branch circuit, both set at the 80-amp rating. The two are interconnected by some kind of a communications connection, and they talk to each other. When two cars are charging simultaneously they both charge at 50% rate. With only one car calling for a charge, it switches to full rate.


Ya I can understand that but just plan for running the circuit as I describe as a dumb charger not the smart charger style .,,

I have a good reason for this ., 

If some kind of commuation fail then both charger can run full tilt on and can trip the feeder circuit.

That you have to keep in your mind some owners are very crafty on this one due some can find a way to beat the " power game "


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## mikewillnot (Apr 2, 2013)

HackWork said:


> My concern is if they don't get another Tesla (which sounds like it's a possibility), then they won't have that feature and won't have the ampacity left for a typical 40A charger.


good point. it had occurred to me. the only scenario where the original plan would work is if C2 is something that charges on a 120v, 20a circuit. otherwise, it's time for another sub-feed. Or maybe he'll want to take that step now.


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## HackWork (Oct 2, 2009)

mikewillnot said:


> good point. it had occurred to me. the only scenario where the original plan would work is if C2 is something that charges on a 120v, 20a circuit. otherwise, it's time for another sub-feed. Or maybe he'll want to take that step now.


That's why I recommended running 2 feeders now. It will be much easier and cheaper to do it at once. And in the meantime he will have a subpanel to do whatever he wants with. So you can sell him on running other circuits for various things.


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