Pre-wire or conduit for EV charging circuit?

[wkearney99]

Since we're building a new house it occurs to me it might be wise to plan for the eventual use of an EV or hybrid kind of car that could be charged at home.  The area where the cars park isn't far from the electrical panel but would have a lot of finished drywall in-between the two.  
 
Anyone pre-wired or at least ran conduit to accommodate this eventuality?  
 
The someone came out with a reasonably priced EV with a convertible top, the size of my wife's beloved VW Cabrio we'd be all over it.  That's 'real' convertible, not some half-assed sunroof like the Fiat 500 (nifty little cars as the are).  A real, fold down and open the compartment sort of thing.  Otherwise we'll likely get a Mini next year.
 
But "while it's open" seems like as good a time as any to plan ahead.  
 
Thoughts?  What size conduits are the 220 volt chargers requiring?

 

[BraveSirRobbin]

just run three 12 gauge wires to an outlet box on the exterior.  Just put a blank panel on it.  I would just leave the wiring unterminated in the box (wire nut all ends for safety).
 
would you need conduit if its inside a wall (even if it's unfinished drywall)?  I don't know enough about code for that one.

 

[wkearney99]

I don't suppose you'd need conduit at all if it was properly installed.  Not unless something additional was needed.  Or perhaps empty conduit is less expensive and wouldn't require changing the electrical permit. I'll run it by the electrician this week.

 

[apostolakisl]

Here is what I would consider.
 
1) Is it a short run, like 10 or 20 feet?  Just put in the wire.  And use big wire, like 6 gauge.  The wire doesn't cost that much for a short run.
2) Is it a long run?  If so, put in conduit.  You kind of hate spending hundreds of dollars on a long run of 6g wire only to never use it.
 
Either way, I would prepare for lots of amps.  Better to have more available than necessary.  If battery technology ever really gets good where you could actually drive a car 300 miles on one charge, it will take a lot of amp hours to fully charge, and you'll want to do it in a couple hours or less, not 12 hours.  The volt has a 16kwh battery and it only goes 40 miles if your lucky.   Imagine a battery that is 60kwh, if you want to charge it in 4 hours, that would be at minimum 15,000 watts, or 60 amps at 240v. 

 

[tmbrown97]

You can't leave individual conductors in the wall - you can however leave romex because it's all bundled together (but, you can't put romex inside conduit either).  I'd do 1" conduit if at all possible - sure today smart cars use a small 220V circuit, but the future is things like the Tesla that can fully charge the car in like 30 minutes - but to do that, they're going to require a seriously large gauge wire!  IMNSHO, run large conduit - then you can run 220v/30A today, then 220V/200A in 3 years.

 

[wuench]

Just remember if you use something like 6 or 8 make sure it has a ground wire (if you need one).  (i.e. 6-2 with ground).  When people say 10-2 they usually mean 10-2 w/ground, when they say 6-2, they usually mean 6-2 w/o ground.
 
I ran into that when running a hot tub circuit.  You do not want to be stripping it down the road and finding out it doesn't have the correct number of conductors.

 

[apostolakisl]

You can't leave individual conductors in the wall - you can however leave romex because it's all bundled together (but, you can't put romex inside conduit either).  I'd do 1" conduit if at all possible - sure today smart cars use a small 220V circuit, but the future is things like the Tesla that can fully charge the car in like 30 minutes - but to do that, they're going to require a seriously large gauge wire!  IMNSHO, run large conduit - then you can run 220v/30A today, then 220V/200A in 3 years.

 
They have jacketed wire for in wall use that includes the ground.  I have a bunch of it my house going to the HVAC units.  It is aluminum 6 gauge wire, good for 50amps.
 
The aluminum stuff is waaaayyyy less expensive than copper, but you do need to go up roughly one gauge to get the same ampacity (still waaaaayyyy less expensive).
 
I kind of doubt you will ever be pumping 200amps into your car though.  The charging circuitry would be quite expensive and the electric co would have a fit if any significant number of people suddenly started yanking 200amps off the grid like that.  The infrastructure just isn't there.  If anything like that ever came to pass, it would no doubt be linked to a regulator of some sort that would throttle you down when they don't have the capacity, kind of like they do with those thermostats that they shut down for 10 minutes at a time during peak demand.
 
But if you did think you ever wanted 200 amps at your car charger, you would never fit that into 1 inch conduit.  Your talking about 3/0 or 4/0 wire.  That stuff is gigantic.

 

[JimS]

I would just run conduit.  Too hard to guess what you will need down the road and conduit is cheap compared to wire.  As mentioned, 1" is minimum, maybe bigger depending on future wire size.
 
Then again, you could just put a subpanel in the garage and run garage and nearby house circuits from there.  Makes it much easier to add things later and all the circuits I needed more than filled the main box anyway. 

 

[Neurorad]

Repairing drywall in a garage, when it comes time to install what you need, is actually very inexpensive. Dirt cheap.

 

[wkearney99]

If it was a garage, sure, drywall's cheap.  But there isn't a garage and the driveway is right next to where the home theater is going to be installed.  Pulling apart THAT drywall would NOT be cheap (2x5/8" with green glue and channels).  Doing something now is a LOT more cost effective than after the theater is installed.
 
I'm leaning toward a 1" conduit with appropriate pulls for adding wire later.

 

[JimS]

Keep the number of bends to a minimum to make the pull easier, especially if you get close to max fill.  I think four 90s is max recommend but just two can be difficult with large fill.  If there are any doubts a box in the middle can help.

 

[Neurorad]

I understand why you need to address the issue now; thought you were inside a garage.
 
I think wiring for a 60 amp (or other higher voltage) surface mount exterior subpanel at the EV point of use might be easier than figuring out pull box sizes and using THHN wire inside conduit.  If you're set on using conduit, I'd consult an electrician.  I don't know the max VA rating of the blue Carlon flex.
 
It might be as easy as installing a 50 amp receptacle at the EV charging location.  You could cable for the 50 amp, and convert as needed to 20A, 30A, 40A, or 50A when you buy a car.  I don't know what the difference in price would be for the 20A v 50A cable; probably less than flex conduit, at a buck a foot, plus the large pull boxes.
 
This is a link to Leviton's EV prewire kit page:  http://www.leviton.com/OA_HTML/SectionDisplay.jsp?section=37737&minisite=10251

 

[Neurorad]

Some googling shows that 6/3 'Romex' type NM wire is $120 at HD, for 50 feet.  125 Feet is $220. That may be all that is needed for a 60A subpanel, but I'm not an expert.

 

[Neurorad]

The AHJ can help with sizing of the 'El' pull boxes.
 
From what I gather, you're unsure of the eventual size of the needed cable.  I'm saying that it may be cheaper just to oversize it, and install it now, especially when considering the higher cost of THHN conductors, in a conduit.

 

[apostolakisl]

The AHJ can help with sizing of the 'El' pull boxes.
 
From what I gather, you're unsure of the eventual size of the needed cable.  I'm saying that it may be cheaper just to oversize it, and install it now, especially when considering the higher cost of THHN conductors, in a conduit.

 
I tend to agree with this approach.  Although I don't see any need for a sub-panel.  Just a 50amp receptacle is all you will need.  You can plug your charger into that or pull the receptacle out and put whatever they want.  
 
And I doubt you will ever need more than 50amps.  I just can't imagine that the electric co's would let people install charging stations that draw more than that.  Think about some day in the future and everyone has an electric car, and they all come home from work and plug their car in to charge at 6pm.  Even at 50amps per car, that would be a disaster for the electric co, especially if it is a summer day and all those hvac units are running.