Installing 4-prong charger on 3-wire 240V distribution

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DGLEAF19

New member
Joined
Aug 19, 2020
Messages
3
Hello,
I bought a '19 S-Plus a few months ago, and recently realized that I could easily tap off of the 240V circuit in my laundry room and put a 240V outlet into the garage, which is adjacent. The way we drive it, charging on 120V is fine almost all of the time (especially under Covid), so it's really not worth it for me to hire an electrician, but I figured it was such an easy thing to do, I might as well spend the $50 or so for materials and do it myself. If we limit charging to 3.6 kW and make sure we're not using the dryer at the same time, the 30-amp circuit is more than adequate.

So last weekend I went to the hardware store, bought the materials, and put in the outlet with about two hours of effort. Pleased with myself, I excitedly plugged in the car, and ... nothing happened. No charging, no blinks from the charging lights or anything. After thinking about it overnight, I realized the problem probably had to do with the Nissan-supplied charger being smart enough to recognize that I had not grounded the equipment ground socket of the 4-prong outlet. My house is somewhat older, so the circuit I'm working with has two hot conductors and a ground wire, but no neutral. So when I installed the outlet, I used the ground wire as the neutral, thinking that a 240V load should have essentially zero neutral current. Of course doing that left nothing to connect the ground socket of the outlet to, which is why the charger refused to work. Duh. So next day, I ran a jumper between the ground and neutral sockets of the outlet, plugged it in, and esto-presto the car began charging at 240V.

Here, finally, is my question: I know that this is a code violation, but on the other hand, this is precisely the way that my dryer has been running, at almost twice the amperage and on the same circuit, for over 20 years without a problem--and there is no code violation in the way the dryer is wired (it uses a 3-prong plug/outlet). Am I making a mistake here or creating an actual hazard? Should I de-energize the outlet and go back to 120V?
 
EVSEs do not use Neutral, so the correct way to connect one is with two Hots and a ground. I suggest you replace the 4 prong outlet with the correct 3 prong if there is no real Neutral available. At worst, label the outlet as having no neutral and disconnect the improvised Neutral. Two Hot and one Ground are all you need there.
 
Thanks Leftie! The thing is that the Nissan charger uses a 4-prong plug, so I have to use a matching outlet.
 
In your case I personally would have hooked your neutral wire to the ground socket on your 14-50 outlet and leave the neutral unused on the 14-50 outlet. Where does the neutral come from, is it a dedicated wire running back to your panel or does it simply come from the box ground? Others(Whitney?) probably know the true code but I just don't like the idea of bonding the ground and neutral at the outlet. As Leftie said L2 EVSEs don't use the neutral and I don't believe the OEM EVSE looks for a neutral but it for sure needs a ground.
 
Thanks to LeftieBiker and JJeff. I connected the ground wire to the ground plug and disconnected it from the neutral. Charger is working like a dream.
 
DGLEAF19 said:
Thanks to LeftieBiker and JJeff. I connected the ground wire to the ground plug and disconnected it from the neutral. Charger is working like a dream.

Good news! Now don't forget to label the outlet "NO NEUTRAL".
 
If we limit charging to 3.6 kW and make sure we're not using the dryer at the same time, the 30-amp circuit is more than adequate.

I had a thought while I was away from the site: I'm wondering how you are doing this with the Nissan supplied dual voltage charging cable, which is NOT adjustable...
 
A couple comments:

A valid allowed-only-for-existing 3-wire circuit for a dryer or stove outlet actually is an ungrounded 240/120V circuit, it has a neutral but no EGC. The dryer or stove is allowed to use the neutral for bonding the case of the equipment, something not otherwise allowed downstream of the electrical service disconnect.

I think the proper way to do this install is to use a NEMA 10-30 receptacle (again, ungrounded 240/120V), and then to procure a small pigtail that is 10-30P to 14-30R in which the 14-30R ground is connected to the 10-30P neutral. That way the fixed parts (the 10-30R) are all wired in the standard way, and all the "weirdness" is in the pigtail, which can be appropriately labeled.

Cheers, Wayne
 
alozzy said:
FWIW, a 10-30p to 14-30r adapter cable can be purchased here:

https://bit.ly/34jGfwb
If using the OEM Leaf L2 EVSE wouldn't the OP need a 10-30p to 14-50r? One way around this would be to cut off the neutral prong on the EVSE as it doesn't use the neutral anyway but then you'd run into the issue of plugging a 27.5a non-adjustable EVSE into probably a 30a circuit.......this would be a better option to do with an adjustable EVSE like Juiceboxes or others.
 
alozzy said:
FWIW, a 10-30p to 14-30r adapter cable can be purchased here:

https://bit.ly/34jGfwb
Which is just here:
https://www.evseadapters.com/products/nema-10-30p-to-14-30r-dryer-adapter/

(I'm not sure why you used bit.ly to obscure the link)
 
Probably already got this info but you NEED ground. You don't need neutral so you can just wire them together (which is what 4 to 3 prong dryer adapters do anyway) and you should be charging at 5.88 kw (24 amps) not 3.8 so unless you get an EVSE that is set to 24 amps, your EVSE will try to pull 6.6 from the wall which would be not good.

EVSE's come in all sizes. Clipper Creek is a good option simply because it offers all power levels with just about any plug you want.
 
LeftieBiker said:
If we limit charging to 3.6 kW and make sure we're not using the dryer at the same time, the 30-amp circuit is more than adequate.

I had a thought while I was away from the site: I'm wondering how you are doing this with the Nissan supplied dual voltage charging cable, which is NOT adjustable...

He isn't and you are right. The EVSE will try to pull 6.6 KW so he needs to get something else. Clipper Creek has a full line of options available.
 
The easiest answer is to get a charger that has the same 3 prong plug as your receptacle.
Might be limited to 4.8 to 5.7kw.
But I find 3.6kw is plenty and I run up 900 to 1,600 miles per month, trumpvirus or no trumpvirus on my leaf with 0 public charging.
 
The ground/neutral discussion is getting ahead of things. As far as I'm aware, "tapping" a 240V circuit is not allowed at all by code. A 240V breaker is meant to protect one, and only one load. Saying "we'll be careful" is not sufficient.
 
Nubo said:
The ground/neutral discussion is getting ahead of things. As far as I'm aware, "tapping" a 240V circuit is not allowed at all by code. A 240V breaker is meant to protect one, and only one load. Saying "we'll be careful" is not sufficient.

The way to handle this is with a Either/Or switch that allows only one of two loads to be on the circuit at any one time.

There is also a way to kinda-sorta comply with the NEC on this charging setup - emphasis on the "kinda": don't charge for more than 2 1/2 hours at a time. This complies with the spirit of the 80% load rule, if not the letter. The problem is that unless you set a charge timer every time, or use an outlet timer of some sort, you are bound to forget to unplug after 150 minutes eventually.
 
Nubo said:
The ground/neutral discussion is getting ahead of things. As far as I'm aware, "tapping" a 240V circuit is not allowed at all by code. A 240V breaker is meant to protect one, and only one load. Saying "we'll be careful" is not sufficient.

Depends on the type of circuit.
Any home appliance or evse circuit, no. 1 breaker, 1 unbroken run of wire to 1 receptacle. There are listed exceptions to appliances being tapped for 120v receptacles but these are rare.
 
LeftieBiker said:
Nubo said:
The ground/neutral discussion is getting ahead of things. As far as I'm aware, "tapping" a 240V circuit is not allowed at all by code. A 240V breaker is meant to protect one, and only one load. Saying "we'll be careful" is not sufficient.

The way to handle this is with a Either/Or switch that allows only one of two loads to be on the circuit at any one time.

There is also a way to kinda-sorta comply with the NEC on this charging setup - emphasis on the "kinda": don't charge for more than 2 1/2 hours at a time. This complies with the spirit of the 80% load rule, if not the letter. The problem is that unless you set a charge timer every time, or use an outlet timer of some sort, you are bound to forget to unplug after 150 minutes eventually.

The definition of continuous depends on the load up to 3 hours I know is used for lighting and heating circuits but the term continuous can mean as little as 20 minutes on appliances, such as an evse.
Ultimately code comes down to what what the inspector will and will not sign off on.
My professionally designed completely legal state inspected solar power generation system is actually not up to code because you can only back feed 20% of what a panel is rated for. My name plate is 9.5kw, 30 actual amps are back fed into a 125 amp panel. That 125 amp panel with 30 amps going back technically, according to NEC is over loaded.
But the state inspector signed off on it, but not worried about it and I'm highly proficient in this line of work. I installed that 125 amp panel to back feed a 3 or 4 kw name plate system, not 9.5kw.
 
I have a sort of similar question. I had a dryer plug installed in my garage that has 240 30 amp on it. I ordered a charger from SplitVolt that is only supposed to charge at 24v. It worked once but then messed up then next time. They're sending me another one. However, I ordered a 14-50 to 10-30 adapter plug from them to try and use with the Nissan charger that came with my 2020 Leaf. According to the Nissan manual, it charges at a continuous 30 amps. When I plugged in using the adapter it seems to work fine and my circuit breaker didn't trip when I turned on overhead lights or ran the garage door opener. Does the Nissan charger have built in intelligence to limit the amps it charges at? Also, I've heard of people limiting how high of amps their Leaf charges at. Can I do that on my 2020, i.e. limit it to lets 24 amps?

Thanks :)
 
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