Building New Home - Required Wiring for Charger

[smkettner]

Even with a 300+ mile range to replenish... a 50a connection would be fine at home. JMHO

 

[ERG4ALL]

I wired the circuit myself per code. I used #8 ga. wire with a 40A breaker. I wasn't sure if the AeroVironment charger used any 120V for ancillary uses, so I put in three wire plus ground (i.e. red, black and white neutral plus ground). That would allow the 240V current to use the red and black and if there were any circuits that needed 120V for displays or other functions they would have the white to be matched up with a red or black for 120V. I say that because I don't know the requirements of other chargers that you may want to install. As it turns out the AV charger does NOT need both 120V and 240V so I could have gotten by with just a two wire plus ground. The #8 ga. must be used if you want to get 40A power. But the nice thing is that #8 ga. is rated up to 55A (Renewable Energy Handbook, pg. 550). Thus, if down the road you get a higher capacity charger, you won't have to replace the wiring. Because this is for overnight charging, I see no reason to put in larger wiring, #6 would allow up to 75A which in my opinion is overkill. 50A would give you 12,000 watts of power as opposed to the 3,300 watts that we are currently using. Thus, in the future, for an 8 hour charge you'd get 96kWh and at 4 miles per kWh would mean nearly 400 miles of range for an overnight charge.

One other consideration is, that at least where I live, you must have a switchable outlet within 30 feet of the wall unit. I placed my wall unit within 30 feet of the breaker box and was able to eliminate that expense.

Finally, as I said I did all the wiring myself and had the wire sticking out of the wall when the AV electrician showed up. He saw what I had done and joked that he'd leave his tools and go to lunch and I could install the unit myself. :lol: The total install was a little over $1,400 but I had to work for it. I took pictures of the wiring, the breaker and the building permit (we were building the garage at that time). I went back and forth with AV through Nissan phone calls and had sent the pictures to AV. I finally got a realistic price when I had the Nissan rep stay on the line while I got the AV rep to finally concede that a reduction in their normal $2,000 price was in order. I felt very good to get the $1,400 price because I live in the country and the electrician that was authorized to do AV installs had to drive about 200 miles to get to my place.

 

[mitch672]

Even with a 300+ mile range to replenish... a 50a connection would be fine at home. JMHO

Well, it would be limited to 40A from a connected EVSE (%80), which is 9.6KW (40A * 240V), so sure, it would work, but it would take twice as long as an 18KW EVSE (90-100A).

If you are wiring a new house, and have the choice, space and ability to pay for the 100A circuit (the wires are double the size/gauge of the 50A circuit, and its also a larger conduit) thats the best possible choice for any possible EV in the future.

If a Tesla Model S is in your future, go for the 100A connection, nothing like being able to refill your 300 mile range in 5 hours from dead empty, also if you are on a TOU rate, this applies even more as they are typically for a few hours overnight, and you will be using a lot of KW to charge that beast up

 

[jcesare]

Even for a home scenario, I'll take the 6.6kW charger over the 3.3kW charger any day, because I don't ONLY charge overnight. I charge during the day, too, all the times, especially on the weekend, when the off peak rate applies all weekend long.

+1
My situation also.

 

[Volusiano]

But the nice thing is that #8 ga. is rated up to 55A (Renewable Energy Handbook, pg. 550). Thus, if down the road you get a higher capacity charger, you won't have to replace the wiring. Because this is for overnight charging, I see no reason to put in larger wiring, #6 would allow up to 75A which in my opinion is overkill.

Size 8 awg is only rated up to 55A IF you have 90C insulation rating on your wire. Otherwise, it only has 40A rating for 60C insulation rating.

Size 6 awg is only rated up to 75A at 90C insulation rating. Otherwise, it only has 55A rating for 60C insulation rating.

So unless you know for a fact that you have 90C insulation rating, don't assume that your #8 has 55A or your #6 has 75A. If you don't know your insulation rating, assume that it's 60C insulation and based on this, your #8 is only 40A and #6 is only 55A max.

 

[planet4ever]

Well, They have put in a 50 amp. 240v circuit. I took a a photo of the wiring , I want it to be ready for the next generation on of charging. Its a 6/3 stated on the wiring, what ever that means???????????????. Is this what I need for future quick charging,

One possible misconception here. "Quick Charge" is Nissan's term for high voltage DC charging through the CHAdeMO port. 50A at 240v isn't nearly enough to utilize that fully. The most you can get out of that circuit is 9.6kW, which would take at least an hour and a half to go from low battery to 80%. But nobody is going to be putting chargers capable of 30 minute Quick Charges into their garages, so that is not a problem.

Ray

 

[wwhitney]

Size 8 awg is only rated up to 55A IF you have 90C insulation rating on your wire. Otherwise, it only has 40A rating for 60C insulation rating.

Size 6 awg is only rated up to 75A at 90C insulation rating. Otherwise, it only has 55A rating for 60C insulation rating.

So unless you know for a fact that you have 90C insulation rating, don't assume that your #8 has 55A or your #6 has 75A. If you don't know your insulation rating, assume that it's 60C insulation and based on this, your #8 is only 40A and #6 is only 55A max.

That's a good start, but it's a bit more complicated than that.

First, if you are using NM cable (Romex), you are limited to the 60C ampacity. [Even though NM cable is constructed using conductors with a 90C rating.] So #8 NM Cu cable is only good for 40A.

Secondly, if you are using a different wiring method, such as conduit with individual conductors, you may be able to use the higher 75C or 90C ampacity. However, your circuit ampacity is limited to the weakest link, which is usually the connections and terminations. In particular, all residential breakers will have a termination rating of at most 75C. [They should be labeled.] So unless you do something tricky with changing wire sizes in the circuit, the circuit ampacity will be limited to the 75C rating of your wire. Moreover, you can only use that 75C ampacity if the equipment terminations are also rated for 75C.

There's more to it, but that's enough for now.

Cheers, Wayne

 

[Volusiano]

Wayne, you're such a wealthy source of knowledge! Thanks for the clarification!

I was getting dizzy reading up on how complicated it is, though.

By equipment termination rating at 75C, do you mean like the EVSE temperature rating? For example, if you 6 awg is 75C rated for 65A, but if your EVSE is rated for 65A at 60C, it's still no good because while your EVSE is same rated for 65A like the wire, it's under rated for 60C because it's below your wire's 75C rating?

 

[wwhitney]

By equipment termination rating at 75C, do you mean like the EVSE temperature rating?

Typically the lug in the equipment on which you terminate your wire will have a temperature rating on it. For simple equipment like an EVSE that should be the termination rating. The equipment spec sheet should also have that info. For a breaker, however, the termination rating is often lower than what is stamped on the lug and should be printed on the breaker body. That is because a circuit breaker is certified not to trip below its rated current at its rated operating temperature (typically 40C). To do this it depends on the length of wire terminated on it to act as a heat sink. So the breaker might use a lug stamped 90C, but the breaker body says the termination rating is only 75C or 60C.

Cheers, Wayne

 

[Devin]

50amp is good for the next generation and the third generation many years away.

If you happen to be in line for a Tesla Model S, I would wire a 90A or 100A circuit, and use a CS-90/CS-100, that will charge at the full 75A rate (18KW) that J-1772 is capable of, the initial Tesla Model S's are comming with a 300 mile pack, that could use it. Other than that 1 EV, 32A MAX (40 AMP circuit), will be good for anything else out there.

http://www.clippercreek.com/index.php?option=com_content&view=article&id=84&Itemid=164" onclick="window.open(this.href);return false;

http://www.clippercreek.com/documents/PDF/product_information/commercial/ClipperCreek%20CS%20Series%20Brochure.pdf" onclick="window.open(this.href);return false;

I'd also recommend wiring for 240V/100A is you're building new and have the resources to do it. This will ensure you're future proof. I've been talking to some friends who are placing their reservation for a Model S Signature Edition next week and have been trying to figure out charging options.

Right now in my garage I have 240V/60A but that's currently split (at a panel in the garage) to 1x240V/40A (which the AV EVSE is installed on) and 1x240V/20A (which has a L6-20R for the evseupgraded portable charger). In the future I could easily remove the separate legs and upgrade to a ClipperCreek CS-60 (or similar) that would give me 11.5kW should I have a vehicle that can handle it.

 

[smkettner]

If you want to future proof you better have 100a for every possible vehicle you may own and for your visitors. So 100a x3 in a 3 car garage and maybe two circuits out front for a visitor (2 x 100a). Looks like 500a to me to be future proof. So that puts you at probably an 800 amp panel :shock:

Or you can be reasonable about it. But I would rather have three 40s compared to a single 100a.

 

[mitch672]

If you want to future proof you better have 100a for every possible vehicle you may own and for your visitors. So 100a x3 in a 3 car garage and maybe two circuits out front for a visitor (2 x 100a). Looks like 500a to me to be future proof. So that puts you at probably an 800 amp panel :shock:

Or you can be reasonable about it. But I would rather have three 40s compared to a single 100a.

Well hell,while your at it, call your electric company and tell them you want "75KVA 3 phase 120/208" service for your future DC fast charger

"just put the pad mount transformer over there", as they are stringing the 13.8KV lines to your property (BTW, we renovated a commercial property and did just that, replaced a very old 240 "Delta" service, they where glad to see go, I actually got to strip and prepare that coaxial line they use for the 13.8KV, and install the 3 right angle HV connectors on the transformer side, and also the pole top side, they just come by and inspect and connect them up when you are done, that was fun)

100A is a good choice to wire to a garage, just wire it to a subpanel, and from there install PVC pipe to a few spots for future EVSEs, could be a single 90A, or (3) 30A, or (2) 50A, etc. There is nothing wrong with being prepared. You can also install a dedicated 120V 20A, and an 20A dedicated L6-20R outside the garage for your future guests EVs

 

[Devin]

Or you can be reasonable about it. But I would rather have three 40s compared to a single 100a.

100A is a good choice to wire to a garage, just wire it to a subpanel, and from there install PVC pipe to a few spots for future EVSEs, could be a single 90A, or (3) 30A, or (2) 50A, etc. There is nothing wrong with being prepared. You can also install a dedicated 120V 20A, and an 20A dedicated L6-20R outside the garage for your future guests EVs

Exactly. Rather than have 3x240V/40A lines run to your garage have a singled 240V/100A line to a subpanel and split from there as necessary. As in my 240V/60A situation this provides for an easy upgrade to a higher current charger than having to run new wire and also makes a much cleaner run from the electric panel to the garage. Seems much more reasonable than running 3 independent lines from your main panel.

 

[JimSouCal]

Or you can be reasonable about it. But I would rather have three 40s compared to a single 100a.

100A is a good choice to wire to a garage, just wire it to a subpanel, and from there install PVC pipe to a few spots for future EVSEs, could be a single 90A, or (3) 30A, or (2) 50A, etc. There is nothing wrong with being prepared. You can also install a dedicated 120V 20A, and an 20A dedicated L6-20R outside the garage for your future guests EVs

Exactly. Rather than have 3x240V/40A lines run to your garage have a singled 240V/100A line to a subpanel and split from there as necessary. As in my 240V/60A situation this provides for an easy upgrade to a higher current charger than having to run new wire and also makes a much cleaner run from the electric panel to the garage. Seems much more reasonable than running 3 independent lines from your main panel.

Exactly Plus One. I am doing the plans for a remodel, and aim to relocate the electric drop right to the garage! This was my thinking for other reasons (will treat the current panel as a sub), but it means the mains will be right in the garage, and I will be set to do whatever is needed, included adding a TOS meter easily, and efficient use for power billed (minimum line loss).