Electric car: power hub

[yeldogt]

As part of my rebuild I am going to install a connection for an electric car out in the driveway ... wondering if any electricians here have installed one.

Some cars require a 30 amp line .. others are calling for a NEMA 14-50 with a 50 amp circuit beaker and 40-amp continuous circuit. Am I correct that the wire would need to be rated at 50-amp?

They use a NEMA type 3R outdoor box -- looks typical. Some cars need an external charger others have it built in.. gets complicated.


The Tesla fast charge is 100 amp! #2 or #3 copper .. I'm not doing that.

 

[75gmck25]

Home Depot carries 6/3 copper cable (50 foot package, or by the foot) that would work for a 50 amp circuit breaker and receptacle. The cable is stranded, so its relatively flexible and not too hard to work with. I would just run that cable for now and terminate it with whatever receptacle you need at this point (30 amp?). If you have to switch to a NEMA 14-50 later for another vehicle you will already have the correct cable in place.

Bruce

 

[yeldogt]

Was wondering if I could use a direct burial cable.

I don't presently own an electric car.

I'm going to have this house for a long time ... It is a bit remote and having an electric car would be ideal for most trips

 

[MoonRise]

Unless there is some sort of duty-cycle 'exemption' for wire ampacity rating, whatever circuit breaker you have feeding the circuit determines what wire gauge you have to use (taking into account possible derating factors such as conduit fill and voltage drop concerns).

The breaker is there to protect the wiring.

If the 'device' at the end needs 30 amps of current, you can (generally) run that device off of a 50 amp circuit just fine.

If the device needs 50 amps of current, you can't run it off of a 30 amp circuit.

 

[yeldogt]

Unless there is some sort of duty-cycle 'exemption' for wire ampacity rating, whatever circuit breaker you have feeding the circuit determines what wire gauge you have to use (taking into account possible derating factors such as conduit fill and voltage drop concerns).

The breaker is there to protect the wiring.

If the 'device' at the end needs 30 amps of current, you can (generally) run that device off of a 50 amp circuit just fine.

If the device needs 50 amps of current, you can't run it off of a 30 amp circuit.

I understand all of that ... the code is full of strange "exceptions" and I was not sure why the 40amp load was mentioned. I understand the 50amp breaker/ outlet. I was wondering if this was like an AC unit where you can run a 12g to something that look like it should require a 10g

 

[alfredeneuman]

I understand all of that ... the code is full of strange "exceptions" and I was not sure why the 40amp load was mentioned. I understand the 50amp breaker/ outlet.

If a load runs for 3 hours or more, it's deemed to be "continuous" and the circuit has to be sized at 125% of the load. 40 x 125% = 50

 

[Stuart in MN]

For reference, Article 625 of the 2014 NEC covers electrical vehicle charging systems.

 

[wssix99]

The Tesla fast charge is 100 amp! #2 or #3 copper .. I'm not doing that.

You say that now, by who knows what things will be like when you buy your next car? You may want to consider future-proofing by running conduit that will allow you to pull a larger service, if you ever need one.

 

[yeldogt]

If I ever get a Tesla it would go to the garage .. I have power inside.

I'm trying to think of upgrades that are not going to add a huge expense to an already expensive project.

 

[inphx]

I used the tesla power guideline (dreamer ... ) in my new build - locating it at back of car if you pull in.

http://www.teslamotors.com/sites/default/files/pdfs/NEMA_14-50_Overview.pdf

 

[rockwithjason]

conduit stubs would be the way to go here. bury a 1 in line and stub it up in the area you like. cap it off and it will be there when you need it.

 

[ForceFed70]

If it was me, I'd install a standard 50A RV receptacle with a little extra room in case I need to swap it out.

Don't bother with anything over 50A. Yes, Tesla's fast charge system is 100A but Tesla also doesn't recommend it as a daily charger - it's hard on the batteries to charge them that quickly. The fast chargers are ment to replace a roadside gas station where the customer is standing around waiting for the fill/charge. It's not ment to be used at home.

 

[wyliesdiesels]

Was wondering if I could use a direct burial cable.

I don't presently own an electric car.

I'm going to have this house for a long time ... It is a bit remote and having an electric car would be ideal for most trips

Theres no reason u couldnt use direct bury cable.

But If it were me, i would run conduit that way u have options. Size the conduit to the largest conductors u MIGHT run say #6...

 

[yeldogt]

I used the tesla power guideline (dreamer ... ) in my new build - locating it at back of car if you pull in.

http://www.teslamotors.com/sites/default/files/pdfs/NEMA_14-50_Overview.pdf

Thanks everyone.

The Tesla information page is what pointed me to the outlet size -- but I missed the garage digram on that cut sheet .. thanks.

So no standard on the port location -- many have it on the front driver fender. Tesla in rear -- can't we make anything easy. The front is easier.

I spoke to the electrician and running the #6 copper line adds almost nothing to the electrical bid as we are backfilling almost 4' of dirt and it can run with other lines. He is telling me the buried wire is better as we will have too many turns with conduit.

 

[Speedy Petey]

If a load runs for 3 hours or more, it's deemed to be "continuous" and the circuit has to be sized at 125% of the load. 40 x 125% = 50

If the load is expected to run for three or more hours it is to be considered continuous.
There is a difference.

I'm not sure a car charger runs at full load for that time or if the load fluctuates.