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I just purchased an EV car. Unfortunately, my electrical box is a long way away from my garage and the box wouldn't support 50 more amps. I'm looking to use my dryer power supply, using the NeoCharger (https://www.getneocharge.com/smart-splitter).

My issue is that my garage has an upper area where the laundry is. A junction box to the dryer outlet, with 30 amp 240 service, is within five feet of my EV car on the lower level. I want to connect the NeoCharger there but am running into issues with how to wire it.

Can I take the feed from the 240v outlet and add a plug to it and plug it into the NeoCharger (wired to an outlet I would install in place of the junction box)? In essence, the 240v dryer outlet would now get power from being plugged into the NeoCharger. I would then plug the EV charger into the other side of the NeoCharger. Is there another way to make this work? 30 amps (24 usable) is fine for my needs for EV charging.

In the alternative, I could just put the NeoCharger where the laundry area is, buying a long extension cord to go to the lower part of my garage, but that would require the extension cord passing through the floor or wall to the lower level. Any way to make this alternative work?

Thanks for any help!

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  • Why won't the panel support another circuit? Is all the breaker places full or you just added up the amount of amps for the breakers and came to the amount of main breaker? If charger needs 50 amps, your dryer circuit can only supply less than 30 amps. Extension cords are not for permanent installations.
    – crip659
    Mar 2 at 15:09
  • I'm good with the circuit only supplying 24 amps (80% of the 30) and can set the charger to make sure it pulls that amount. The main breaker is both full and would go over the amperage. It would also be a very expensive pull. Is there any way to use the SplitVolt in my application?
    – Farcical
    Mar 2 at 15:16
  • I'm pretty sure all EV outlets require a dedicated circuit. Anything else would void all warranties. Maybe upgrade the dryer circuit and add a sub panel close to the junction box.
    – JACK
    Mar 2 at 15:24
  • This one is UL approved. Is there any way I can make this work in my setup? getneocharge.com/smart-splitter
    – Farcical
    Mar 2 at 16:42
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    Is this a 3-prong or 4-prong dryer outlet? With a 3-prong, the deal is off, unless you run 4-wire cable or install a $100 GFCI breaker. I know they make 3-prong adapters, but they are illegal. Mar 2 at 19:10

3 Answers 3

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This unit. Hmmm.

The UL Listing on this unit looks legit, I'm looking at a photo of a unit "in the wild" with a proper File Number and yet a 3-prong socket. My research thoroughly checks out, they even applied for a California research grant. This is a small "mom & pop" US company that builds in California for Pete's sake - fully within reach of US regulatory talons. The UL listing can only be legit. Clearly, they found a way to make the NEMA 10 style connection less dangerous (?) in a way that fully satisfies UL.

So a first - no McKayla Maroney face from me, my tail is wagging. However their product doesn't make any sense for two EVs - Share2 does that, and does it better.

However, when UL approves an item, they approve paper instructions. These are important as they define the scope of testing, and they MUST be followed per NEC 110.3, and override any "more fun" multi-media instructions. Hiding them is a red flag. I'd like to see them.

It may not be necessary at all.

There is no limit to the number of receptacles on a 30A circuit. This has come up in the past here, and we have not been able to find any rule against this. So I do not see a problem with simply extending a legal, grounded 30A circuit to the garage and having a second receptacle there. Don't use the dryer and EV at once.

Note that an ungrounded circuit cannot be extended, unless you retrofit ground to the original location. (the GFCI solution below does not allow extension).

Those pesky ungrounded circuits and NEMA 10 receptacles.

NEMA 10 is a World War II era connector that does not provide safety ground. The madness of using this should be obvious. Even worse, on dryers, Code says to bootleg chassis ground to the neutral, on the logic that NEMA 10 sockets are rarely disturbed -- however, if they are disturbed and the neutral wire loses contact, this guarantees the chassis of the machine will be energized with 120V. Guarantees. The media reports these fatalities as a "miswired" socket, it was correctly wired and simply wore out. That shouldn't be possible, hence the ban.

Code never forces retrofit of things which were legal at the time of installation; this is called "grandfathering". However, such circuits cannot be modified or extended.

There are generally 3 solutions to a NEMA 10 outlet:

  • Open it up and discover there are separate neutral and ground wires in the box after all, or metal conduit rated to provide ground. Code required all dryer sockets to be wired this way as soon as the supply of ungrounded 3-wire was exhausted.

  • "Retrofit Ground" to that location using the now-liberal retrofit rules. A #10 ground can be run back to the panel obviously, or to the Grounding Electrode System (that bare wire going off to ground rods), or to any junction box with #10 or larger ground going back to the panel. (Grounds can be shared among circuits, since they only carry current during a fault).

  • Leave the circuit groundless, GFCI-protect the circuit at the breaker, fit a NEMA 14-30 receptacle with ground unconnected, and mark it "GFCI Protected / No Equipment Ground".

That is why I'm so keen on seeing the UL-approved instructions. Perhaps they approve 3-prong pass-thru to a dryer. If they do, that is that. (why would they approve that? Does the unit have GFCI?)

Proper in-wall wiring, though.

Routing an extension cord through a wall is not legal and cannot be done. Any thru-wall wiring must be done with proper in-wall wiring methods, e.g. NM cable and junction boxes in jurisdictions which allow NM cable (not Chicagoland).

If you are simply extending the circuit, this is straightforward standard wiring.

It is perfectly legal to use in-wall wiring methods in walls to connect an inlet to an outlet, that is otherwise isolated. For instance you could have a 10/3 NM cable in the walls between two junction boxes, with a NEMA 6-30 or 14-30 socket on one end, and a NEMA 6-30, L6-30, 14-30 or L14-30 inlet on the other end. Jay613 wisely pointed out in another discussion that the "L" twist-lock inlets may be more readily available than the non-"L". Then have an adapter cord that takes an L-x-30R (inline socket) to a "normal" 6-30P or 14-30P.

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  • So, if an EV charger doesn't need a neutral, and you have a 3rd wire that is connected at the panel to a shared neutral/ground bus, and your dryer uses it for both neutral and ground .... who is to say that the charger's perspective is wrong? It's as much a ground as any ground as long as the dryer is properly disconnected from it. No? If the circuit is fed by a subpanel I'm out of my depth .... I don't know if or how a 3-wire dryer gets connected to a subpanel.
    – jay613
    Mar 2 at 22:16
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    @jay613 Code. Neutral is not ground, and "inside the main panel" is not the same place as "anywhere else". Neutral being ground at the panel is about as useful as a Javelin at the Polish border. If you tie neutral to ground, badness happens, and if you distribute it, the badness is distributed. Neutral is usually not switched in devices like these, so consider the situation where neutral gets loose on the panel lug, and someone switches on the dryer. Normally the dryer chassis is energized, but what happens to the EVSE frame and vehicle body? Mar 2 at 22:38
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Adding this answer just to show what a Frankenstein's monster you'll need to build to do this "properly" with the device you've proposed given your existing wiring, location of devices, and the way this Neo gadget works.

This is all premised on having a 4-wire supply from the panel, (live/live/neutral/ground) as you confirmed in a comment.

A bunch of new boxes "downstairs" to house an outlet and two inlets. The cable to the dryer is in the existing box, but now connects to a new inlet via new wires through Conduits A and B. Conduit C serves only to supply grounding to the charger without relying on the Neo device for ground. IE if you unplug the Neo or if it fails, the conduit and boxes to the charger are still grounded.

This is outrageously expensive and ugly for what it provides. Surely there is a device that works like the one you found but is designed for installation inside a junction box? Look!

You'll have to find two short power cords with NEMA 14-30 plugs and L14-30 sockets, or you'll have to find non-locking inlets.

enter image description here

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    Thanks for all of this. You've definitely convinced me that the Neo is not the way to go for my setup if I want to do it to code. Sure, I could hook up the Neo next to the dryer and run an extension through the wall/ceiling to the EV charger "downstairs" but I don't want to violate code. Wiring a DPDT switch looks like the easiest way to go.
    – Farcical
    Mar 8 at 20:04
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I just noticed that the device you want to use to switch power between your charger and dryer costs $500. A system of outlets and inlets that would allow it to be used would cost you another $100. All this is in aid of time-sharing your last remaining 24 amps between the two devices and postponing the installation of a proper feed wire to your garage.

Here's my advice: Don't waste so much money!

You said your charger is within five feet of a junction box carrying the wires on the way to your dryer.

Just install a manual DPDT switch such as the Leviton 1288 or Hubbell 1388 (for example) next to the charger and get into the habit of using it. Your car will have power at night, your dryer in the day. If you need to dry clothes at night you'll need to go downstairs and flip the switch.

The switch can go in a normal junction box, probably in the existing one with an ordinary face plate and you won't need any NEMA 14-30 or 10-30 plugs or sockets or cables.

I know it's not what you asked but now I've seen the price I have to make this suggestion as a better way to temporarily plug the hole, and saving the $600 or so to put towards a better permanent solution.

You still need to consider the issues in Harper's answer, determine whether there is a proper ground wire available in the junction box and act accordingly.

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  • The junction box has three wires and a ground. Unfortunately the junction box is in the joists, about a 10-foot run to where the EV charger is, so is not easily accessible for the switch. I'm guessing I could have the wire run to a single box with the switch and then back to the dryer outlet ?
    – Farcical
    Mar 8 at 16:05
  • 4 wires (3+ground) is good. I wrote the answer based on "5 feet to the charger on the lower level". So use the junction box as a junction box, run some conduit form it, down the wall to where you want a switch, and put the switch (or a franken-assembly of outlets and inlets for the Neo device) on the wall there. A conduit to the charger can go from the switch location or from the existing junction box location. You'll have to fill in details according to the exact layout of your building and wiring.
    – jay613
    Mar 8 at 16:51
  • Thanks @Jay613! This is probably my solution. Just to confirm what I think has been said above, for the Romex path that runs from the dryer outlet through the ceiling and currently terminates at the junction box, I could attach a 14-30 plug to the 10 AWG Romex and then plug that into the Neo? The power would need to be converted to a receptacle for the Neo, and I would run 10 AWG Romex hard-wired from the EV Charger and add a 14-30 plug to that to plug into the Neo?
    – Farcical
    Mar 8 at 18:44
  • I don't think you can/should do exactly as you describe. You're describing a highbbrid where you have cables acting both as in-wall wiring and as extension cords (with plugs) at the same time.
    – jay613
    Mar 8 at 18:53
  • Thanks @Jay613. If I went with the Leviton 1286 switch you suggested, can you point me to guidance on how to wire it so that when the switch is one way it feeds the EV Charger and feeds the outlet when it is the other? Thanks for your help on this. A switch seems like the most economical solution by far.
    – Farcical
    Mar 8 at 19:18

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