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Discussion Starter · #1 · (Edited)
SPX Voltec 220v charge station (EVSE) doesn't need a neutral

Just in case anyone else was confused by this at one time.

General: Installing 220 / 240 volt Electrical Circuits: http://www.nojolt.com/basic-220-circuits.shtml

Frequently asked Question:
Why do some 220 circuits have a neutral wire and others don't?
Because some appliances contain 110 volt internal circuits (such as timers and electronic displays) which require a neutral connection to comply with current codes. When these 4 wire appliances are connected to old 3 wire systems via a 3 wire pigtail they use the ground conductor for the neutral. Other "straight" 220 appliances such as water heaters have no need for a neutral because the current both feeds and returns by way of the two hot wires as the current polarity alternates. Ideally, in any circuit the ground wire serves only as a safety feature and never carries any current under normal circumstances.
Also:
Ground and Neutral Connections
All modern 220 circuits will also have a ground wire which is identified by either green insulation or by being bare metal with no insulation. The ground wire connects to the ground bar. Some 220 circuits will also have a white insulated neutral wire which connects to the neutral bar, or to the combined neutral / ground bar.
Also:
Understanding 220 or 240 volt Electrical Circuits
http://www.nojolt.com/Understanding_240_volt_circuits.shtml
Now for the quick explanation of 240 / 220 volt house current; Appliances which use straight 240 current (such as electric water heaters, or rotary phase converters) also have three wires:

  1. A black wire which is often known as the "hot" wire, which carries the current in to the fixture.
  2. Another "hot" wire which may be blue, red or white (if it is white the code actually requires it to painted or otherwise marked one of the other colors, but often it is not) which also carries current in to the fixture.
  3. A bare copper wire called the ground, the sole function of which is to enhance user safety.
That's it, no neutral. Now, if you are paying attention, then you are probably wondering "If there isn't a neutral wire then how is the circuit completed?" The answer is that when one hot wire is negative, then the other is positive, so the two hot wires complete the circuit together because they are "out of phase". This is why 240 volt circuits connect to double pole breakers that are essentially two single pole breakers tied together. In the main panel, every other breaker is out of phase with the adjoining breakers. So, in essence 240 volt wiring is powered by 2 - 120 volt hot wires that are 180 degrees out of phase.
 

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This is elementary knowledge for the Electrical Engineer members in this forum, and I am one. But for the layperson, there is not enough formal training about the difference between Direct Current flow (the Edison view) and Alternating Current flow (the Tesla view). So the more common DC view of the layperson cannot see that the two 110 volt live lines that feed every home are in opposite phase (180 degrees out of angular phase output of the rotating generator) and can provide 220 volts of "pressure" and thus need no neutral or return flow to circulate the electrons.

Tesla knew about the use of ground (the natural Earth) as the return conductor for all electrical circuits (including lightning) to the source, so we who studied how Alternating Current flow works also understand what is the real purpose of the Neutral line. The Ground conductor (normally a green color as we visualize our ground image of the Earth) is a protective return, so if any device attached to the electric line has new and accidental path from that live line exposed (commonly known as a "short circuit" although it isn't a shorter path), that new path doesn't flow through the user, and instead flow through the protective "ground return" back to the distribution panel and back to the real ground. That new circuit can overload and trigger the circuit beaker to trip and open the live line, and break open the new circuit (this is why they are called "circuit breakers"). The home owner should apply caution and respect when working with any electrical circuit.

So if there are any questions about electrical power and wiring, let the EE members answer them, and always consult an EE or an licensed electrician before installing or changing any electrical power installation in your home. The Volt uses both DC and AC, so it also deserves the caution and respect of the user, and consult the dealer before working on it.

Raymond
 

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Thanks Scott, I guess I may not have to bug you on facebook, but I wouldn't mind seeing pictures. So does that mean when I wired the neutral, I'm really just putting in a safety-ground using the neutral wire? That kind of sucks. I bet I could have saved money on the wire, but at least it might be ready for a future upgrade.

-Brad
 

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Discussion Starter · #4 ·
Thanks Scott, I guess I may not have to bug you on facebook, but I wouldn't mind seeing pictures. So does that mean when I wired the neutral, I'm really just putting in a safety-ground using the neutral wire? That kind of sucks. I bet I could have saved money on the wire, but at least it might be ready for a future upgrade. -Brad
Brad, attached is a picture of my subpanel wiring.
subpanel wiring (Large).JPG

Raymond, thanks for taking the time for the informative post!
 

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Ah, I had my dad check it out. He does residential as well as industrial electrics. He told me that the way I had it was perfectly fine for residential. He said that my installation was fine, and using the neutral wire to connect the ground to the bus bar, as well as all the dedicated grounds hooking into the neutral bus bar was fine for residential wiring. Everything tested just fine too. I was concerned as my whole house is wired that way. All the extra "3rd prong" grounds are just wired into the neutral bus bar. He told me all about industrial wiring and why things would be different here and there and all he did was confuse me. I'll try to read up on it more someday. The goal now is to pull some wall panels and drill some holes and get this baby mounted permanently.

Thanks for everything! -Brad
 

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Brad, attached is a picture of my subpanel wiring.
View attachment 991

Raymond, thanks for taking the time for the informative post!
Technically, I se a few things wrong with the sub-panel in the photo.

1. The grounding conductor (green) coming from the main panel should be at least as large as the feed wires. In the event of a fault to ground, the smaller grounding wire will fail first the way you have it.

2. There should be a ground bar in addition to the neutral bar, rather than tying both ground wires under the same mounting screw. This ground bar should be electrically bonded to the metal case of the sub-panel.

3. I can't tell from the picture if this is the case, but you should verify that the neutral bar with the white wire is NOT connected to ground or the metal case at the sub-panel. It should only be bonded to ground at the main service entrance panel.
 

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Only reason to have a neutral is to provide 120 volt in the SPX for some auxilary purpose, which in fact does not need. Recived mine last week and now have a thorough understanding of what is in it. Installing my sub panel next week. I had a 40A circuit available to me that was not used anymore just moved it over to the garage for the subpanel. Wire is aluminum but is No 6 which is to code. Sub will give me 240 @ 20 A and 2 120 at 20 @ each. Will use one 120V for a small AC compressor, for tire maint. on the car and tracktor. Need to get this done, as my Volt order has gone to 3000. Can't wait!



P
 

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Discussion Starter · #8 ·
3. I can't tell from the picture if this is the case, but you should verify that the neutral bar with the white wire is NOT connected to ground or the metal case at the sub-panel. It should only be bonded to ground at the main service entrance panel.
The ground is only bonded to the neutral in my main panel. I did not use the bonding screw that came with the subpanel to tie the neutral to a ground.

My whole house is in conduit (grounded) as is the run from the main to this subpanel. In theory this ground wire is not needed at all and the EVSE could have been grounded to the subpanel box only. Since the EVSE was/is very sensitive we ran another wire...which of course is only to trip the breaker.

The friend that helped me with this install is a professional electrician doing both commercial and residential.
 
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