Help with home charging on a new construction house...

[acarney]

I've had a NEMA 14-50 installed by what I thought to be a licensed electrician on a very old house (built in the 1960s) and where I'm renting (built 3 years ago) I asked the landlord to split the cost to install a 14-50 and both times the panel was 200 amps. The old house was electric heat (that had it's own sub panel I believe) and the newer house is gas heat. Both times they looked at the panel and saw blank space and tossed a 50 amp circuit in for the outlet.

I'm having new construction built (1900 sq ft) and when I ask about a pre-wire for a vehicle charging circuit they're saying it MUST be upgraded to a 320 amp panel and the pre-wire states that it's 100 amp service. My goal is to put a wall connector in this time around so I would like a 60 amp circuit.

I'm wondering if I actually need this (total cost between the panel [$3400] and pre-wire [$2210] is over $5500.... for a vehicle charging circuit... while the house is being built... panel is in the garage and at most I would want about 50 feet of cable run (30 foot wide garage, but if they run around or through the ceiling that would be some extra feet).

This seems.... excessive to me. But, I will say, it's a 1900 sq ft house, with a heat pump (so electric heat) and electric stove/oven. I've also requested three additional dedicated 20 amp circuits in different places in the house. So... maybe the panel upgrade to 320 amps isn't such a bad idea? (potentially 60 amps of dedicated circuits, plus HVAC/Kitchen, plus 60 amp for the Tesla + normal life stuff?)

Guess I'm just looking for some general input on this and if people think the 320 amp panel is needed... I figure if I just skip it and stuff it into the 200 amp panel I probably could hire an electrician to do it for under $2000... maybe under $1000? If I stick with the panel upgrade, but ditch the pre-wire option then I'm not sure how much I would actually save when I have it done after move in... if someone charges me $1200 or something... sure, I saved a little, but it's a hassle...

 

[acarney]

Oh, also to state, I'm in the Tri Cities area of Washington State (Richland, WA) if anyone has recommendations for electricians that did EV charging for reasonable cost... or have built with New Tradition Homes before and opted for the EV pre-wire. I kind of suspect it's just going to be a subpanel that runs to where ever I want it on the plans... in which case, does the wall connector need a subpanel break out? I had to have an ugly box on the wall six inches away from the sleek Tesla wall connector... that's the whole reason I'm getting the wall connector this time, I want the sleek integrated look... the 14-50 plug was plenty fast...

 

[brainhouston]

overkill going for 320 imho
is panel in garage? ie close to where u need 14-50?
what if u ask for just a standard dryer outlet without mentioning EV? is the answer the same?
if builder refuses to do with 200amp, just finish the house as is then add it urself later or hire another electrician

i added 100amp WC gen2 to my 200amp panel but i have gas
its all about not using all 200amps at the same time, which likely u won't if charged at night...

 

[bruce4000]

TWC can be configured for a 60 down to 15 amp breaker (48. - 12 amp charge rate). I just had a new panel installed with 50 amp breaker and TWC in old house with 200 amp service. Make sure they don’t put a GFCI breaker in for hardwired TWC as stated in the manual. For my use, frankly I could have gone with s smaller breaker as I found that charging at 31 amps gives my MY 10% charge per hour so even at this lower rate can fully charge overnight. They need to do load calc for your house.

 

[ewoodrick]

I've had a NEMA 14-50 installed by what I thought to be a licensed electrician on a very old house (built in the 1960s) and where I'm renting (built 3 years ago) I asked the landlord to split the cost to install a 14-50 and both times the panel was 200 amps. The old house was electric heat (that had it's own sub panel I believe) and the newer house is gas heat. Both times they looked at the panel and saw blank space and tossed a 50 amp circuit in for the outlet.



Guess I'm just looking for some general input on this and if people think the 320 amp panel is needed... I figure if I just skip it and stuff it into the 200 amp panel I probably could hire an electrician to do it for under $2000... maybe under $1000? If I stick with the panel upgrade, but ditch the pre-wire option then I'm not sure how much I would actually save when I have it done after move in... if someone charges me $1200 or something... sure, I saved a little, but it's a hassle...

A builder is often going to make things hard or expensive just because they don't want to do it.

Ask for the load calculation on the current panel and see how much free space is there.
And I think that you may have blinders on. I'm guessing you are thinking about charging a single car. But what about two? For a new build, I'd go with a 100A subpanel in the garage.

Depending on where the panel is at vs the garage, post build installation can easily be more expensive.

 

[acarney]

So the panel is in the garage... possible on the "wrong" wall so maybe 30-50 foot of cable to run... I also will have the garage walls and ceiling insulated, so probably a huge pain to run it.

The builder seems more than happy to install it, they list it as a standard optional add on (this isn't a fully custom house, it's pretty production line style with just a number of optional upgrades you can request). But they have the pre-wire for EV linked with requiring an upgrade to the panel...

Can they do a fairly accurate load calculation before the home is built?

I really want the wall connector and NOT a 14-50 outlet, I'm sure if I asked for a NEMA 14-50 it would be much cheaper and might not require a panel upgrade (granted the 14-50 is half the amps that their "EV station" pre wire lists.

It is for a single car... I only have a single EV... maybe this would also be a nice future proof... but I kind of think even if I was limited to just one plug I probably could live with it, I only use about 10% of battery a day on my Tesla...

 

[brainhouston]

keep in mind that WC could be had with ~18/24ft cable
its not really necessary to have it on the "right" wall...

 

[ewoodrick]

So the panel is in the garage... possible on the "wrong" wall so maybe 30-50 foot of cable to run... I also will have the garage walls and ceiling insulated, so probably a huge pain to run it.

The builder seems more than happy to install it, they list it as a standard optional add on (this isn't a fully custom house, it's pretty production line style with just a number of optional upgrades you can request). But they have the pre-wire for EV linked with requiring an upgrade to the panel...

Can they do a fairly accurate load calculation before the home is built?

I really want the wall connector and NOT a 14-50 outlet, I'm sure if I asked for a NEMA 14-50 it would be much cheaper and might not require a panel upgrade (granted the 14-50 is half the amps that their "EV station" pre wire lists.

It is for a single car... I only have a single EV... maybe this would also be a nice future proof... but I kind of think even if I was limited to just one plug I probably could live with it, I only use about 10% of battery a day on my Tesla...

They absolutely can do a load calculation before the house is built. They should actually have it somewhere. That's because the electrician is going to install only what the contract calls for.

Go for the 14-50 outlet or even just a circuit terminated at a wall box. Once the wire is there, you can pull the 14-50 and put the wall connector in.

Yes you can live with a single outlet, but now's the easiest time not to get restricted by a single outlet.

I have two Teslas that I alternately charge off of a single 120V 15A plug. It works, but I'd much rather have two circuits.

And as for a single car. How long do you expect to stay in the house? In 20 years you think that you may only have one EV?

 

[jjrandorin]

But they have the pre-wire for EV linked with requiring an upgrade to the panel...

This just sounds like money generation to me. There is no need at all for the line to be a 100amp line. They are putting in a 100amp line to drive the need to upgrade the panel. You should be able to get a 60 or even 50amp line for it from them without the panel upgrade.

This is just them trying to standardize, and also make extra money somewhere (at least it seems like it to me).

 

[golferguy]

Why does pre-wire state it needs a 100A service? What is source of this? Typically they are 60A direct wire circuits. 100A can be done, but is not common.

 

[acarney]

Why does pre-wire state it needs a 100A service? What is source of this? Typically they are 60A direct wire circuits. 100A can be done, but is not common.

I suspect they probably just picked a large capacity and went with it thinking that EVs need HUGE POWER. The sales person I've been working with has been really knowledgeable on just about everything except for this... I get the feeling not many people take this option. She's trying to track down some information for me, but I'm almost positive it's just going to be a 100 amp subpanel...

 

[acarney]

But I'll also state that I don't really know how this all works... it might be rare, but I could see a potential of having an electric oven running, an electric cooktop running (maybe three burners), the heat pump with electric resistance backup heat running, and me coming home from somewhere and plugging in the car sucking down 48 amps. Heck, maybe even the laundry machine running.

Again, rare, but Christmas or Thanksgiving or something when the kitchen is busy, we have a cold snap, and I'm charging... I feel like that could get up to 170 amp right there without counting TVs, lights (though they're all LED disk lights) etc...

Do panels also have the same kind of rating that you should only use 80% capacity for extending durations?

 

[ewoodrick]

I suspect they probably just picked a large capacity and went with it thinking that EVs need HUGE POWER. The sales person I've been working with has been really knowledgeable on just about everything except for this... I get the feeling not many people take this option. She's trying to track down some information for me, but I'm almost positive it's just going to be a 100 amp subpanel...

100A would be what is generally recommended for two vehicles. Don't think about what you have today, think about 10 to 20 years from now.

 

[ewoodrick]

But I'll also state that I don't really know how this all works... it might be rare, but I could see a potential of having an electric oven running, an electric cooktop running (maybe three burners), the heat pump with electric resistance backup heat running, and me coming home from somewhere and plugging in the car sucking down 48 amps. Heck, maybe even the laundry machine running.

Again, rare, but Christmas or Thanksgiving or something when the kitchen is busy, we have a cold snap, and I'm charging... I feel like that could get up to 170 amp right there without counting TVs, lights (though they're all LED disk lights) etc...

Do panels also have the same kind of rating that you should only use 80% capacity for extending durations?

There are accepted guidelines defined by the National Electric Code that are used for the load calculations.

Christmas and Thanksgiving aren't rare, they each happen yearly and the NEC takes them into consideration.

The code does allow for the total of all the breakers to exceed that panel breaker, but it is well defined.

And that's where we get the constant loads must be derated to 80% of the circuit capacity, because that's a the EV connector is.

 

[Earl]

I'm trying to understand what the problem is here.

Is there some conception that 320 Amp capability is fundamentally bad? Like an ICE car creating emissions?

Or Is the OP concerned about getting ripped off by the builder?

If the latter: I haven't seen what the cost of something else. I've had to upgrade the electrical entrance of my last 2 houses and realized that the cost of over-sizing the new upgrade was insignificant compared with incrementally increasing it. The first house had a 100 amp entrance and we could upgrade it to 150 amps or 240 amps for, perhaps $100 difference on a $1200 job. The next house was undersized at 150 amp entrance but we found that increasing it to 400 amps was about as cheap as to anything else. The big expense for both jobs was the addition of a new service panel and running a new line in from the street. We never came near to using all 240 amps or 400 amps in either house, but, other than a couple $ hundred extra of installation cost, neither have cost us anything since.
The benefit is that we have no concerns about future electric upgrades to heat pumps or worry about Xmas and Thanksgiving.

I'd recommend that the OP tell the builder that EV charging may not be that important and ask what current and cost it would be without an EV. This would get an estimate of the cost difference.

 

[Rocky_H]

@acarney Huh, interesting issue. And of course I love weighing in on installation threads.

You have two separate questions here: What size circuit should you get? And would that push it over the limit into requiring a panel upgrade?

Many people reflexively ask for a 60A circuit. You say you want to get a wall connector (which I agree with), but it doesn't have to use a 60A circuit. It's built as a variable setting device. So maybe you could get a 30 or 40A circuit, and that wouldn't need to push it into a panel upgrade. But electric heat for a house is a very heavy load, so I don't know how close to the limit this is currently.

And yeah, that builder's thinking of "Electric car = extra 100A" is just ridiculous nonsense. But it's not uncommon. I see posts online frequently that are kind of FUD / disinformation / fear mongering that are stating flat-out that an electric car just CAN'T use anything less than a 75A circuit, so of course it requires huge expensive upgrades to the house's electrical, so you should neeeever consider buying one of these boondoggles! (Did I make the sarcasm clear enough there?) There's no problem with using a smaller circuit to keep it from getting into the territory of expensive upgrades.

And yes, I would recommend a wall connector instead of trying to do any kind of outlet like a 14-50 or 14-30. Those have to use finnicky, nuisance tripping GFCI breakers, which are more expensive and just a pain in the butt.

 

[acarney]

I'm trying to understand what the problem is here.

Is there some conception that 320 Amp capability is fundamentally bad? Like an ICE car creating emissions?

Or Is the OP concerned about getting ripped off by the builder?

If the latter: I haven't seen what the cost of something else. I've had to upgrade the electrical entrance of my last 2 houses and realized that the cost of over-sizing the new upgrade was insignificant compared with incrementally increasing it. The first house had a 100 amp entrance and we could upgrade it to 150 amps or 240 amps for, perhaps $100 difference on a $1200 job. The next house was undersized at 150 amp entrance but we found that increasing it to 400 amps was about as cheap as to anything else. The big expense for both jobs was the addition of a new service panel and running a new line in from the street. We never came near to using all 240 amps or 400 amps in either house, but, other than a couple $ hundred extra of installation cost, neither have cost us anything since.
The benefit is that we have no concerns about future electric upgrades to heat pumps or worry about Xmas and Thanksgiving.

I'd recommend that the OP tell the builder that EV charging may not be that important and ask what current and cost it would be without an EV. This would get an estimate of the cost difference.

I guess to help understand I'm more asking... should I skip the pre-wire and panel upgrade direct from the builder. If I can just hire an electrician as soon as we close and get the keys on the finished house and they install the wall connector for me and it's like $750 or something because they don't need to upgrade the panel.... then that's golden.

BUT, if it turns out they say they have to upgrade to 320 amp and it's nearly the same cost (or more since everything is finished already, and walls and ceiling are insulated), then I just want to eat the cost now and have the builder do it...

If I hadn't had two 50 amp circuits installed before on 200 amp panels with no one even bringing up the question of upgrading the panel I wouldn't be in this position... I just really don't know how to figure out the load and how close we might be. On one hand, when I think about all the high demand electric stuff, a 200 amp panel seems small when factoring in over 25% of it's capacity JUST for an EV. But... I was in a house built in the 60s with no electric upgrades that had electric heat (3 ton heat pump and back up electric heat elements), electric stove/oven, electric dryer, etc and they tossed a 50 amp circuit in a 200 amp panel no problem. Did I just hire a questionable electrician for that... or is the 320 amp panel overkill because the builder is setting aside a potential 100amps for the car instead of my 60 max that I need (of which the most I'll use with a single Tesla is 48)

 

[ewoodrick]

Does the panel have the capacity? That you would determine from a load calculation.
Is the panel in the garage?

My panel is on the other end of the house and would require routing outside and going under two sidewalks, and 100+ ft. $5000 is considered cheap.

Is there another similar house from the builder that you could get someone to do a load analysis on?

 

[APotatoGod]

320 Amp service sounds completely unnecessary and overkill for a single car, or even 2 of them to me.

We had a 60A connection to our HPWC with only 125A service, and now also added a NEMA 14-50 outlet along with a solar install (I'm not sure how much the solar installation is meant to supplement the overall circuit rating, but we still have the same 125A main breaker.)

 

[ewoodrick]

320 Amp service sounds completely unnecessary and overkill for a single car, or even 2 of them to me.

We had a 60A connection to our HPWC with only 125A service, and now also added a NEMA 14-50 outlet along with a solar install (I'm not sure how much the solar installation is meant to supplement the overall circuit rating, but we still have the same 125A main breaker.)

But the car isn't the only user of the panel.

Sure, your 125A panel may have been able to add a NEMA 14-50, but that means that it was only halfway loaded.
It also suggests that your home is possibly older and smaller than others and the you may live in more northern latitudes.


The argument is NEVER can a 60A or 125A or 200A or 400A panel handle it. The argument is whether the panel in YOUR SPECIFIC house with your specific breakers and your specific load can handle it.

In my house, with a 200A panel, it would not support it. That's why I have a 400A panel.