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Discussion Starter #1
In the world of standard 110/120 house type current their is one type of receptacle which comes either grounded or not.

Why with 240V do so many different receptacles exist? I assume they all deliver the same volts and amps. Or, is the amperage different and therefore the receptacle

Any help appreciated.

Tom
 

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Actually there are several 110/120 outlets as well. ;)

In addition to the ground/no-ground, there's outlets for 15A, 20A, etc. Some are backwards compatible (i.e. a 15A outlet will accept a 5A plug, a 20A outlet will accept a 15A plug or 10A plug), but not all of them.

Example: http://i.stack.imgur.com/xCPV0.png
 

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The different 240V receptacles generally indicate different amperage. But there are also variations within the same amperage offering different features like a plug that locks into the receptacle, etc. It definitely presents a challenge if you want to be able to plug one device in a variety of locations.
 

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If you look at the posted chart you will see NEMA standard. NEMA is the manufacturers association so they will give you many choices.
Around the home most devices don't use much amperage so multiple devices can be plugged into a 15 amp circuit. 240 devices can run much more amps and are more common in industrial and commercial places.
The 6 series provide plugs and receptacles for a variety of amps. The 10 series were the old standard for home dryers and stoves. They are still common in homes built in the 1980s and earlier.
The 14-30 and 14-50 are now the standard in homes.
EVs are late to the party. Most only require the 3 wires of a 6 or 10 series. But it is rare to find an EVSE sold with a 6 or 10 series plug. If you are doing a new installation for EVs you are probably better installing 4 wire and a 14-30 or 14-50 outlet. You are not supposed to put a 14 series receptacle on 3 wire.
 

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In the chart that Neromanceres posted above, the NEMA 10- series had two hots and a neutral. This could (questionably) provide both 120v and 240v power - but no safety ground. They have been obsolete for new installations since 1996. New 120/240v installations require a four-wire NEMA 14- series which has two hots, neutral, and safety ground. The NEMA 6- series has two hots and safety ground so is 240v only.

Although a NEMA 6- series would be fine for most EVs, Tesla seems to have defaulted to the NEMA 14-50 in their UMC (mobile charge cord) for a very practical reason. They sell long range EVs capable of road trips. And while on the road, many/most RV parks and campgrounds offer NEMA 14-50s for use by big rig RVs. Obviously these could also be used for 10kw EV charging in areas where Supercharging is not available. (Tesla also sells a variety of adapters for the UMC for other receptacles. These are nice because they inform the UMC of the max amperage so the car can charge at the correct amperage accordingly. Unfortunately some of the adapters have been discontinued.)
 

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You'll notice the old 10-30, 10-50 have no safety ground. National Electric Code no longer allows these in new construction, replacing them with 14-30, 14-50, which do have the safety ground. Because 240VAC appliances with 10 series plugs often also had 120V needs, the Neutral wire had some current on it, causing a small shock hazard on anything (like the appliance frame) connected to it. By separating Neutral (120V return current), from the appliance frame, and connecting the frame to safety ground, this issue is eliminated.

A 240VAC appliance that has no 120V draw (from the L1, Black wire), does not need the neutral, current passes from one hot wire (L1/Black) to the other (L2/Red). It's also no coincidence that an "L1" 120V EVSE gets its name from being only connected to the L1/black wire, whereas the 240V "L2" EVSE is connected to both L1 and L2 wires.

Outlets provide a fixed voltage. It's up to the appliance or load to draw only what it needs, but always less than the plug that comes with it. If it draws more than that, there's something wrong and the circuit breaker should trip. Each breaker is sized appropriately to the outlet and circuit.
 

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So... is it the opinion of the forum that it would be wise for a new installation to be a NEMA 14-50? I mean...I know it's overkill for the Volt, but down the road, should one choose to get a Tesla or other car that has more needs...wouldn't this be more flexible and future-proof so to speak?
 

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So... is it the opinion of the forum that it would be wise for a new installation to be a NEMA 14-50? I mean...I know it's overkill for the Volt, but down the road, should one choose to get a Tesla or other car that has more needs...wouldn't this be more flexible and future-proof so to speak?
Yes, provided you are feeding it with the matching size wire.
If you're using 10-12ga wire, use the appropriate plug (or direct wire with no plug at all)
 

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So... is it the opinion of the forum that it would be wise for a new installation to be a NEMA 14-50? I mean...I know it's overkill for the Volt, but down the road, should one choose to get a Tesla or other car that has more needs...wouldn't this be more flexible and future-proof so to speak?
If you have the electrician there anyway, it is just one more wire to pull. New homes typically have a 14-30 in the laundry area for a clothes dryer, and perhaps a 14-50 in the kitchen for an electric range. So any electrician is certainly familiar with installing them.

Note that a 30 amp circuit won't charge most of todays pure BEVs (with 6.6-7.2kw charging) or the upcoming Bolt EV at full speed. It would only provide 30x0.8x240=5.76kw. You would need a 40 or more amp circuit. Interestingly, the NEC has an exception allowing a 14-50 receptacle to be used on a 40 amp circuit. Presumably this is because there is no NEMA 14-40 receptacle type.
 
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