Can 120 v. outlet be run off one leg of 208 v. circuit?

[alohart]

I just got a jaw-dropping bid for installing power to my condo parking stall so that I could charge a new i. The bid included running one 208 v. 20 a. and one 120 v. 20 a. circuit from the closest electrical panel which is a significant distance from my parking stall, so 2 separate circuits. I want a 120 v. circuit so that I could charge the i's 12 v. battery for periods when I would be away for several months. Instead of running a separate 120 v. circuit from the electrical panel, would it be kosher to run 1 208 v. 20 a. circuit (2 120 v. legs of 3-phase power) from the electrical panel to my parking stall and then, in my parking stall, connect 1 120 v. outlet to one leg of the 208 v. circuit?

 

[fjpod]

You can... but it's not exactly to code. Why not run the 220 line, then made a splitter adapter that you plug into the 220. that way you can go both ways and still have the hard wiring to code.

 

[Don]

You pose an interesting question. With 3 phase power, all sorts of things are 'possible' but the only thing that matters is what your electrician can and can't do concerning local codes

The answer may be quite different depending on whether your condo is in Hawaii or Sweden, but either way, the person you should pose this question to is your electrical contractor - If anyone here was to tell you 'Yes, this is possible' it still wouldn't do you any good if your electrician refuses to do it because he is constrained by local codes

I would run only the 208 line and then find me a 208 volt trickle charger, since you won't have your EVSE plugged in during the time you need the charger on the 12 volt battery. Something like this one
http://www.ebay.com/itm/Battery-Tender-Waterproof-800-12V-800mA-Univeral-Input-100-240-Vac60-60-201-/320969976812?pt=US_Racing_Fan_Shop&hash=item4abb4d2bec

Don

 

[garygid]

If there is 120v available, then there is usually also
the "opposite phase" of the 120v available, giving
you 240v as an option, in residential settings.

Then, installing 120v takes 3 wires, Hot, Neutral, and
Ground. You can add the opposite phase of the 120v
by adding the other Hot wire. The two "hot" wires are
often called L1 and L2, for Line-1 and Line-2.

Then, with the 4 wires, one could install two 120v
receptacles, or one 240v receptacle. In some cases,
you might even be able to install both on the same
wires, using a 20 amp dual breaker.

It is unusual to have residential 208v in the USA, so maybe you
are talking about some other country?

 

[alohart]

If there is 120v available, then there is usually also
the "opposite phase" of the 120v available, giving
you 240v as an option.

That's only true when each 120 v. leg is 180º out of phase. With 3-phase power, the 3 legs are each 120º out of phase, so using two of these legs results in 208 v. rather than 240 v.

It is unusual to have 208v in the USA, so maybe you
are talking about some other country?

Apparently, 3-phase power is quite common in commercial buildings in the U.S. (Hawaii, in this case). It's described as 208Y/120 or 120Y/208 power (see Wikipedia for the gruesome details).

 

[alohart]

I would run only the 208 line and then find me a 208 volt trickle charger, since you won't have your EVSE plugged in during the time you need the charger on the 12 volt battery.

That's probably the least expensive solution. But I doubt that dropping the 120 v. circuit would reduce the $10,000+ electrical service bid enough to make buying an i worthwhile I'm very bummed.

 

[Don]

Apparently, 3-phase power is quite common in commercial buildings in the U.S. (Hawaii, in this case).

I'd say it's pretty common - In fact, it's all we generate in this country. When you look at high tenson towers you always see three large conductors, each one carrying one phase. The output of our generating plants is all 3 phase and it's used nearly everywhere with the singluar exception of smaller users, like average households

If you need a large electric motor for anything, 3 phase is the only way to go - Large commercial air conditioning systems like those found in office buildings, apartments or condo's are all typically 3 phase units. The advantages are many - Cheaper, smaller motors which use less current and that makes them more reliable, not to mention that most all AC motors need at least a second phase to operate anyway, so running them off true 3 phase is much more efficient

Your EVSE will operate fine from the 208 outlet and with a multivoltage trickle charger, you really have no need for a 120 outlet at your parking stall - Why spend the extra to install one?

Don

 

[garygid]

A residential neighborhood might be supplied with 3 phase 12000v or
24000v AC, with each phase going to different parts of the neighborhood.

Then, some 50:1 or 100:1 transformers step the voltage down to 240v to feed
small groups of houses, through the center-tapped low voltage winding.

That gives a house a floating 240v supply, and the center tap is connected to
ground, resulting in the typical residential "2-phase" 120v service, with
240v from Line1 to Line2.

Commercial buildings would typically get 3-phase, but apartments
would typically need both 120v and 240v for stoves, ovens, and electric
dryers. Usually these high-power devices are not run on 208v, right?

 

[Don]

That gives a house a floating 240v supply, and the center tap is connected to ground, resulting in the typical residential "2-phase" 120v service, with
240v from Line1 to Line2.

True, but it's actually all one phase.

"A split-phase electricity distribution system is a 3-wire single-phase distribution system, commonly used in North America for single-family residential and light commercial (up to about 100 kVA) applications. It is the AC equivalent of the original Edison 3-wire direct current system. Its primary advantage is that it saves conductor material over a single ended single phase system while only requiring single phase on the supply side of the distribution transformer. Since there are two live conductors in the system, it is sometimes incorrectly referred to as "two-phase". The two live or "hot" conductors' waveforms are offset by a half-cycle, or 180 degrees offset, when measured against the neutral wire. To avoid confusion with split-phase motor start applications, it is appropriate to call this power distribution system a 3-wire, single-phase, midpoint neutral system."

Commercial buildings would typically get 3-phase, but apartments
would typically need both 120v and 240v for stoves, ovens, and electric
dryers. Usually these high-power devices are not run on 208v, right?

Yes, but anywhere you have 3 phase 208 it's easy to run that through a transformer and have the conventional single phase 120/240 for all the normal household needs.

"In North America, the high-leg delta system allows single-phase 120 V loads and 240 V three-phase loads both to be served by the same three-phase, four-wire distribution system."

Don

 

[alohart]

Commercial buildings would typically get 3-phase, but apartments
would typically need both 120v and 240v for stoves, ovens, and electric
dryers. Usually these high-power devices are not run on 208v, right?

Our apartment, completed in 2007, has only 208 v. and 120 v. at the electrical panel in each apartment. The electric water heater and kitchen range are powered by 208 v., but produce less heat than they would if powered by 240 v.

I installed a whole-apartment TED electric monitor to keep track of monthly electricity usage and to watch for unexpected electricity usage. It consistently measured ~15% less monthly electricity usage than I was billed for. I complained but was told that my electric monitor must be wrong. Indeed it was because it did not correctly measure the 208 v. loads like the water heater and range.

 

[garygid]

240v 3-phase is not the same as 208v 3-phase.

 

[garygid]

Does the charger in the iMiEV work on 208v AC and 240v AC?

What is the acceptable voltage range, 200v to 250v?

 

[Don]

The Panasonic EVSE that comes with the car (very similar to the one which comes with the Leaf) is only for 120 volts @ 8 amps . . . . but you can send it in to EVSE Upgrade and for about $300 they will modify it so it charges at 12.5 amps on any voltage between 90 and 250 VAC

Don

 

[garygid]

I understand that the EVSE can be modified to work on
any voltage from about 90 to 260 volts.

However, that does NOT mean that the car's charger
will work on 200 or 208 volts.

What voltage range is the CAR specified to work?

 

[peterdambier]

I have learned from 90V to 250V. I guess that means L1 from 90V to 125, same for L2.

L1 + L2 180V to 250V, so 208V lies well within the specs.

Math, integration, says L1 and L2 carry the same power for 208 and 240. So I guess performance or time to charge is the same for 208 or 240.

 

[garygid]

If the L2 spec for the car's charger is 180v to 250v, then
you are correct, 208v is well within that range.

Operating at L2 voltages, the on-board charger is
probably current limited, so charging at 240v would
usually charge the car faster than when charging at 208v.

 

[Don]

I believe the J1772 spec for all Level 2 charging includes 208 volts, so I would suspect most any EV capable of L2 charging would accept 208 volts.

Level 2 Charging

Level 2 equipment offers charging through 240 V (typical in residential applications) or 208 V (typical in commercial applications) electrical service. Level 2 EVSE requires installation of home charging or public charging equipment and a dedicated circuit of 20 to 80 amps, depending on the EVSE requirements

I *think* our charger is wattage limited, so I would suspect the recharge times on 208 and 240 should be the same. It will be interesting to see what's the actual case when someone does it and reports back

Don

 

[DonDakin]

All this talk about voltage got me thinking about the level 1 EVSE that comes with the car.

I think it might be possible to do a very simple mod outside of the panasonic 120V EVSE to get it to charge at 8 amps at 240 Volts.

If you intercept the 120 VAC wires only going from the EVSE to the J1772 and replaced it with 240 VAC then I think the car would charge at 240 V 8 amps or twice as fast as on 120 volts. The 120 VAC wires from the EVSE could power a 2nd contactor that would energize the 240 VAC to the J1772. That way the power up sequence and checking would remain intact.

I could see this being done with a small utility box and a dryer plug and a simple 120VAC relay good for 240 VAC at least 8 amps.

Anybody out there think this is a good idea ? It would be no mod to the EVSE at all and a simple garage install for most of the charging.

Don......

 

[FiddlerJohn]

... If you intercept the 120 VAC wires only going from the EVSE to the J1772 and replaced it with 240 VAC then I think the car would charge at 240 V 8 amps or twice as fast as on 120 volts. The 120 VAC wires from the EVSE could power a 2nd contactor that would energize the 240 VAC to the J1772. That way the power up sequence and checking would remain intact.

I could see this being done with a small utility box and a dryer plug and a simple 120VAC relay good for 240 VAC at least 8 amps.

Anybody out there think this is a good idea ? It would be no mod to the EVSE at all and a simple garage install for most of the charging. ...

The over voltage protection, MOV, and the 12v supply in the OEM EVSE needs to be changed.

 

[peterdambier]

!!! Dont do this at home !!!

Connect your EVSE power side to L1 and neutral. Fish PILOT and PROXIMITY out of the cable to EV.

Connect L1, L2 and neutral (mains) directly to your EV. Connect PILOT and PROXIMITY from EVSE to your car.

If it works, forget about PROXIMITY and feed a +12V square wave, PWM modulated, 1 kHz to PILOT of your car. Now you have got a "notEVSE".

I have heard but not verified, that some EVSEs dont need PROXIMITY. They use it to power a flash light to help you find the J1772 socket of your car.

!!! Forget about warranty and insurance !!!

Dont wait for somebody to build this in a box and sell it over the internet.