240 Volt charging

[ZT6N8FW]

I was interested in the possibility of pre-wiring for 240 Volt charging. The problem is that NO ONE seems to know with any degree of reliability what size wire should be used for the Volt. 240 Volt circuits can probably use anything from 14 AWG to 6 AWG.

As many are probably aware there are at least a dozen styles of 240 Volt outlets. The particular type of outlet to use is not important at this point, what I am trying to figure out is the correct wire size (gage) to have installed in my garages.

[nater]

Install a NEMA 14-50 with 6 gauge wiring. Home Depot and Lowes both sell a very nice outdoor NEMA 14-50 hookup for an RV for about 25 bucks. Breaker it for 50 Amps. If you do it yourself, be sure to remove the jacket if you run it inside conduit. (As required by code) but leave the jacket on if you have it inside a wall/ceiling. (The jacket is the part that holds the wires together; leave the insulator on the actual conductor).

Here is the home depot plug:

http://www.homedepot.com/webapp/wcs/...ctId=100193650

Here's a really nice one that combines a 50Amp 240v with a 20Amp 120v and breakers:

http://www.homedepot.com/webapp/wcs/...ctId=100669936

Or you can do a flush mount in the wall. Mine is done in conduit with double-gang weatherproof cover, even though it's in the garage.

Nate

[ZT6N8FW]

This would be for a new house.

Where are you getting the '6 Gage'? Are you guessing?

Is GM keeping the 240 Volt charging information a secret?

Why do you think a NEMA 14-50 Receptacle is correct?

[RobertSullivan]

The second like shows:

Connecticut Electric 60 Amp RV Panel with 50A Receptacle, Breakers & GFCI Duplex
Model CESMPSC55GRHR
$108.71/Each

[nater]

Nema 14-50 is the correct choice for many reasons. It is the standard plug for RVs, Ranges (the stove/oven in your house) and for newer welders. Also, many homes only 100 Amp service from the utility, so going above 50 Amp (loaded at 80%) would exceed many homes' ability to support the load (at the pole!). Newer homes generally have 200Amp service, so this is not an issue, but as far as picking a standard, it would have to top out to accommodate everyone, so Nema 14-50 it is.

A little secret; most Nema 14-50 outlets can support a Nema 14-30 plug if you notch the plastic with a dremel. The outlet manufacturers use the same metal attachment for both inside and include a different plastic top for one or the other.

The only other higher Amp Nema standard for single phase (household power) is Nema 14-60 (60 Amp), but it is so rare I've never actually seen one in real life. There are no higher Amp Nema standards for single phase, so if the Nema 14-50 isn't the right one for futurproofing, you have no hope of having the right one.

The Tesla has a proprietary 90 Amp service, but its hardwired, so you need empty conduit. The Tesla will charge off of a nema 14-50, but it only draws 25 amps, since it doesn't know if it is on a 30 Amp, 40 Amp, or 50 Amp circuit.

As far as gauge, 6 gauge meets code for a 50 Amp in most residential applications (an ultra long run might need to go thicker). If you guess too thick, you waste a tiny bit of money on copper. If you guess too thin, you waste electricity (as heat loss in the wire) forever.

So, for futureproofing new construction, pull a Nema 14-50, 6 gauge, breakered at 50 Amp. Or, pull empty conduit with pullstring. Those are the best choices.

Nate

[prowler]

Nema 14-50 is the correct choice for many reasons. . . .

So, for futureproofing new construction, pull a Nema 14-50, 6 gauge, breakered at 50 Amp. Or, pull empty conduit with pullstring. Those are the best choices.

Good advice.

The Tesla will charge off of a nema 14-50, but it only draws 25 amps, since it doesn't know if it is on a 30 Amp, 40 Amp, or 50 Amp circuit.

Close. The default on Tesla when plugged into a Nema 14-50 is to draw 30A. If you put it in your house, a 50A breaker is the way to go as you suggested above. When plugged into an unknown outlet, you're OK if it's breakered for 40 or 50, but will blow if only 30.

If it's breakered at 30, the car needs to be manually set to draw 24A since 25A is not an option and would exceed the 80% draw limitation.

-SPARKZZ


P.S. - to put this in perspective, a 110V 20A outlet at 80% should provide a 40 miles charge to the Volt overnight.

[nater]

Thanks, sparkzz. Yes, 24 Amp is 80% of 30 Amps.
The more I think about it, for futurproofing, maybe there should be a 125 Amp subpanel in the garage right where the plug should go. From there you could easily pull a giant Tesla charger or a pair of 50 Amp circuits (for TWO EVs!) without issue.

Plus, it's nice to have local access to the breakers.

Nate

[DaV8or]

From there you could easily pull a giant Tesla charger or a pair of 50 Amp circuits (for TWO EVs!) without issue.

If you can afford a Tesla or 2 EVs, the rewiring of your house to accommodate them is the cheap part of the equation. If it's new construction going on now, fine, put in what ever you can guess the future needs will be (actually I like the empty conduit idea best), otherwise, just wait and see what the real needs will be.

[ZT6N8FW]

A little secret; most Nema 14-50 outlets can support a Nema 14-30 plug if you notch the plastic with a dremel. The outlet manufacturers use the same metal attachment for both inside and include a different plastic top for one or the other.

The above suggestion would void the U.L. rating.

The rest of your advice sounds reasonable to me. However all this is still is an educated guess on your part.

I do not disagree with the assumptions you are making, I am just amazed that G.M. it is silent on this issue. At least ten million new homes will be built between now and the availability of the Volt. Many of these new homes could be equipped with 240 Volt charging if G.M. did NOT keep this information a secret.

[nater]

Plugging a 30 Amp plug into a 50 Amp receptacle is not a problem. Go to Home Depot and familiarize yourself with the two connectors to see what I mean about the notch.

Seriously, a Nema 14-50 is gonna do it for the Volt. I promise.

Nate