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Discussion Starter #1
I'm looking at the different chargers available. Some of them (such as the GM VOLTEC) are listed as 15 amperage units. Others (like the GE WATTSTATION) are listed as a 30 amperage unit.

What's the different? Pardon my noob question, but what does having double the amperage get me?
 

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To keep it simple: It would allow you to keep that charger in use for future car that requires more amperage to charge.
 

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Watts = Amps X Volts so doubling the amps doubles the wattage. This doesn't have any practical value for the Volt, however, since the Volt can only use 3.3 kW which essentially is 240v and 15A (actually 12A but for a continuous draw the breaker needs to be 120% of that draw).

The Volt doesn't care if you have an EVSE with higher wattage. The actual charger is in the Volt and it's going to charge at 3.3 kW no matter how much power the EVSE can supply. Also note that when you install an EVSE you also have to run different gauge wire (heavier for more wattage) and match the breaker to the appliance. The best suggestion is that, regardless of the EVSE and the breaker, to go with heavier gauge wire. Running wire can be expensive and you can always use a heavier gauge, so using a heavier gauge won't cost you much and can save if you want to upgrade the EVSE later.

More specifically, for the Voltec you'd need 12 AWG wire and a 15A breaker but the normal suggestion is to use 10 AWG wire (my suggestion is to use 8 AWG if you have a ten year time horizon because, at the end of that time, we'll be looking at much larger batteries with much higher charging requirements).
 

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A few corrections:
3300W/240V=13.75A
For continuous load, size circuit to 125% of load.
13.75A*125%=17.19A
Next breaker size is 20A.

Also, read the instructions that come with charger; it should state what size circuit to use.


Watts = Amps X Volts so doubling the amps doubles the wattage. This doesn't have any practical value for the Volt, however, since the Volt can only use 3.3 kW which essentially is 240v and 15A (actually 12A but for a continuous draw the breaker needs to be 120% of that draw).

The Volt doesn't care if you have an EVSE with higher wattage. The actual charger is in the Volt and it's going to charge at 3.3 kW no matter how much power the EVSE can supply. Also note that when you install an EVSE you also have to run different gauge wire (heavier for more wattage) and match the breaker to the appliance. The best suggestion is that, regardless of the EVSE and the breaker, to go with heavier gauge wire. Running wire can be expensive and you can always use a heavier gauge, so using a heavier gauge won't cost you much and can save if you want to upgrade the EVSE later.

More specifically, for the Voltec you'd need 12 AWG wire and a 15A breaker but the normal suggestion is to use 10 AWG wire (my suggestion is to use 8 AWG if you have a ten year time horizon because, at the end of that time, we'll be looking at much larger batteries with much higher charging requirements).
 

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Thanks Richard. You're exactly right. It's early and last night was a long one! LOL Need ... more ... coffee.
 

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Discussion Starter #6
Excellent. Thanks for the information. I'm having the wiring done next week sometime. If I'm hearing people correctly, I should tell the guys to wire everything up as if I'm going to install the 30A WattStation just so that if, in the future, I decide I need to upgrade, I'll still be okay, right?
 

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Yes, ask them for prices on 12, 10, and 8 AWG. The Voltec needs only the 12 but other EVSEs need 10 and the next gen chargers may need 8. So you'd want the 10 AWG at least. (The price on the 12 AWG is just so you can see how little difference there is).

Also note that you want the breakers to match the EVSE not the wire! This means 20A breakers regardless of the wire. (The wire can be heavier gauge than what the breaker protects but not lighter gauge).
 

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Excellent. Thanks for the information. I'm having the wiring done next week sometime. If I'm hearing people correctly, I should tell the guys to wire everything up as if I'm going to install the 30A WattStation just so that if, in the future, I decide I need to upgrade, I'll still be okay, right?
Well... You can have them pull wire for a 30 amp circuit. It will likely need to be #8. (Depending on the length of the run.) But they can't instal a 30 amp breaker on a 15 amp Voltec. The Voltec needs to be protected by the 15 amp breaker as recommended in the Voltec installation instructions.

Also... You need to consider that just because your panel may have a open slot left... This does not mean you ca just plug in more breakers and loads to it. Your electrical panel has a maximum amperage rating. (You can't put 10,000 amps worth of breakers in a 350 amp panel. Or it would MELT.) Your electrician will need to evaluate this situation and advise you on your particular installation.
 

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Well... You can have them pull wire for a 30 amp circuit. It will likely need to be #8. (Depending on the length of the run.) But they can't instal a 30 amp breaker on a 15 amp Voltec. The Voltec needs to be protected by the 15 amp breaker as recommended in the Voltec installation instructions.

Also... You need to consider that just because your panel may have a open slot left... This does not mean you ca just plug in more breakers and loads to it. Your electrical panel has a maximum amperage rating. (You can't put 10,000 amps worth of breakers in a 350 amp panel. Or it would MELT.) Your electrician will need to evaluate this situation and advise you on your particular installation.
Well the situation is more simple than that. You can have in your panel the breaker's amperage sum of all circuits giving a higher sum than the
amperage capacity of the main breaker. If the total amperage of the loads exceeds the main breaker amperage, it will simply open.
Electrical panels are designed to be safe and of course, not to melt. What permits having a higher sum is the base that all circuits are
not pulling current at the same time.

For your wiring, if you are installing a 30Amps EVSE, I would have at least a AWG 10 wire installed or an AWG 8 wire, depending on the
distance between the panel and the EVSE. Your electrician will figure that one for you. You can then put either a 30Amps breaker for being able
to recharge any EV cars, or put a 20Amps if you plan to recharge only a Volt, and change only the breaker in the futur when you would augment your charging amperage.

Hope this helps,

Francois
B2653
 

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Well the situation is more simple than that. You can have in your panel the breaker's amperage sum of all circuits giving a higher sum than the
amperage capacity of the main breaker. If the total amperage of the loads exceeds the main breaker amperage, it will simply open.
Well... What you say may be true. However it is a code violation. According to the NEC codebook it's against code to load more breakers into a panel than the maximum ampacity rating of that panel. It's not recommended. It's not safe.
 

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Well... What you say may be true. However it is a code violation. According to the NEC codebook it's against code to load more breakers into a panel than the maximum ampacity rating of that panel. It's not recommended. It's not safe.
You are missing a key point - the rating of the panel is much higher than the rating of the main breaker - the sum of all breakers is almost always higher than the main breaker.

The problem with using larger wire for the Voltec panel is that the terminal on the Voltec reccomend 12ga solid copper wire. I do not know if the much larger 8ga-10ga copper will fit into the terminals - or the even larger gages of aluminum wire often used for 30A circuits. It may be required to add a junction block to convert to a smaller gage at the Voltec, which would be removed if a larger rated EVSE and breaker were installed in the future. The correct breaker for the Voltec is 20A, even if more capable wiring is used.
 

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Oh yes, forgot one point which was just brought up: Don't hardwire the EVSE. Use a connector (plug and outlet), preferably a locking one such as the L6-20. The connector is more convenient and removes the need for permits.
 

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You are missing a key point - the rating of the panel is much higher than the rating of the main breaker - the sum of all breakers is almost always higher than the main breaker.
I totally agree with this. And I disagree about fulgerite comment about not being safe or not following the NEC.

The problem with using larger wire for the Voltec panel is that the terminal on the Voltec reccomend 12ga solid copper wire. Snip!
Just don't forget that the OP indicated the he will install the GE Wattstation EVSE that support a 30A load. The wire requirements that apply are NOT those of the SPX EVSE.
For the GE Wattstation, I still promote/recommend using #10 or #8 AWG wire between the breaker panel and the EVSE.

DonC's suggestion of using a connector is also a very good one. You simplify alot your installation paperwork. But I would go
with a plug that supports 30Amps, like an L6-30.

Francois
B2653
 

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Just don't forget that the OP indicated the he will install the GE Wattstation EVSE that support a 30A load. The wire requirements that apply are NOT those of the SPX EVSE.
...
DonC's suggestion of using a connector is also a very good one. You simplify alot your installation paperwork. But I would go
with a plug that supports 30Amps, like an L6-30.
I don't think he said which one he was thinking about. I assumed he was first looking at the Voltec but he could be looking first at the GE. Whatever EVSE he goes with he needs to match the breaker and the connector. I suspect everyone would agree that he should be looking at 20A -- 10/8 AWG -- 6L-20 if he's looking at the Voltec and 30A -- 10/8 AWG -- 6L-30 if he's looking at the GE Wattstation. Yes?
 

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I just got my Voltec 240v EVSE installed this morning. I did the attic work, pull 12/2 cable up and across. Drill hole in top plate and fish wire down into wall cavity. My electrician friend swapped an unused 30A breaker pair for a 20A and made the connections at both ends. Took us 2 hours start to finish from the panel on one side of the garage to the other side. If the future requires a different EVSE and heavier wire it will be a simple pull. Now I have two green lights and waiting for the wife to bring the car home!
 

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It is a code violation, and the reason is because in order to trip a breaker due to overload, it must reach a certain temperature first. It is entirely possible to heat the wire beyond its design without heating the breaker sufficiently to trip it. This would generally be for a short periods of overload that, over time, will degrade the insulation of the wire, possibly causing a fire. One thing to remember is that the NEC is the minimum requirement for safe operation/installation.

There are a lot of factors that go into adding a circuit to a panelboard, and a loads analysis should be done to ensure the upstream circuit (main breaker, service entrance cabling, etc.) can handle the load. The NEC has examples of how to do this if you are ambitious.

One reason I mention the above comment is because while you are installing the Voltec now, if there is a possibility of putting in a larger capacity charger in the future, you should also do the loads analysis for the larger charger. If your current house wiring and panelboard cannot support the larger capacity charger, then there is probably no benefit to installing a larger wire for the Voltec now, because there will likely be major modifications that need to be made to install the future charger, and I estimate the larger wiring can be put in at that time for little added cost.

Well... What you say may be true. However it is a code violation. According to the NEC codebook it's against code to load more breakers into a panel than the maximum ampacity rating of that panel. It's not recommended. It's not safe.
 

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In my county, you would still need a permit because you are adding a circuit (the receptacle). The cord-and-plug connected EVSE would not need the permit. Replacing light fixtures and existing equipment generally does not need a permit. I suspect this applies for most locales.

Oh yes, forgot one point which was just brought up: Don't hardwire the EVSE. Use a connector (plug and outlet), preferably a locking one such as the L6-20. The connector is more convenient and removes the need for permits.
 

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What you answered is not what he said. It is NOT a code violation to add breakers to a box that add up to more than the main breaker amerage. And it is not unsafe. My main house panel has a 200A main and 570A total for all the breakers, and it is fine and passed inspection. The individual breakers must be sized to trip before the wire on that circuit would overheat, and the main breaker must be sized to trip before the main incoming wire or internal panel components would overheat. The sum of the breakers is irrelevant. [edit: my panel does have a panel max of 1000A, so yes, the breaker sum does have to be less than that. but the breaker sum does not have to be less than the main breaker.]


It is a code violation, and the reason is because in order to trip a breaker due to overload, it must reach a certain temperature first. It is entirely possible to heat the wire beyond its design without heating the breaker sufficiently to trip it. This would generally be for a short periods of overload that, over time, will degrade the insulation of the wire, possibly causing a fire. One thing to remember is that the NEC is the minimum requirement for safe operation/installation.

There are a lot of factors that go into adding a circuit to a panelboard, and a loads analysis should be done to ensure the upstream circuit (main breaker, service entrance cabling, etc.) can handle the load. The NEC has examples of how to do this if you are ambitious.

One reason I mention the above comment is because while you are installing the Voltec now, if there is a possibility of putting in a larger capacity charger in the future, you should also do the loads analysis for the larger charger. If your current house wiring and panelboard cannot support the larger capacity charger, then there is probably no benefit to installing a larger wire for the Voltec now, because there will likely be major modifications that need to be made to install the future charger, and I estimate the larger wiring can be put in at that time for little added cost.
 

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Please read my post again. I did not say to add up the breaker values of the branch circuits, I said to add up the loads (loads analysis). Two different things. It is a code violation to add breakers until the upstream trips (trial by fire), and that's what I was explaining. I was referring to frankydude's suggestion. I guess I should've quoted better. Here's his comment:

" Originally Posted by frankydude
Well the situation is more simple than that. You can have in your panel the breaker's amperage sum of all circuits giving a higher sum than the
amperage capacity of the main breaker. If the total amperage of the loads exceeds the main breaker amperage, it will simply open."

It's not entirely straightforward, because to do it correctly, you need to look at all of the loads serviced by the upstream (main) breaker to determine if you have capacity for additional circuits.

I'll refer you to the examples in Annex D, page 70-804 of the NEC. It should be able to step you through doing the calculations.

What you answered is not what he said. It is NOT a code violation to add breakers to a box that add up to more than the main breaker amerage. And it is not unsafe. My main house panel has a 200A main and 570A total for all the breakers, and it is fine and passed inspection. The individual breakers must be sized to trip before the wire on that circuit would overheat, and the main breaker must be sized to trip before the main incoming wire or internal panel components would overheat. The sum of the breakers is irrelevant. [edit: my panel does have a panel max of 1000A, so yes, the breaker sum does have to be less than that. but the breaker sum does not have to be less than the main breaker.]
 
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