Help an indecisive person decide on an EVSE

[jimmyz80]

How about a 12amp, 16amp, 24amps and 40 amp J1772 all-in-one portable charging cable based on the Tesla UMC:

Only 8 pounds, super flexible, and includes carrying bag and two plugs:

- NEMA 5-15 household 120 volt plug for 12 amps
- NEMA 14-50 plug for "50 amp" RV park or 240 volt garage for 40 amps

http://shop.quickchargepower.com/JESLA-is-THE-40-amp-J1772-portable-charging-solution-JESLA.htm

When you attach the following respective plug, JESLA will automatically provide up to the following amperage:

............................................VOLTS / AMPS.......kW
NEMA 5-15 .......Standard Outlet.. 120 V / 12 A...... 1.4 kW
NEMA 5-20 ...... Motel air conditioner 120/16A....... 1.9 kW
NEMA 10-30......Older Dryers...... 240 V / 24 A...... 5.8 kW
NEMA 14-30......Newer Dryers..... 240 V / 24 A...... 5.8 kW
NEMA 6-50 .......Welding Equip.... 240 V / 40 A...... 9.6 kW
NEMA 14-50......RVs and Camps.. 240 V / 40 A...... 9.6 kW

I like the concept and I've looked into the JESLA in the past, but it just doesn't meet my needs in this case. It's also double the cost of what I decided on.

 

[LeftieBiker]

Install a 30 amp breaker (more common and will still be safe) and upgrade it when you install a larger EVSE. The LCS-25 only draws 20 amps, so you don't want a breaker sized fully twice that.

The required breaker for the LCS-25 is 25A so double sizing everything would mean a 50A breaker. 40A would be the required breaker for a 30-32A EVSE, which is fairly standard and is why I was suggesting that size. My panel actually has a 40A breaker for the 30A EVSE in the garage that I'll likely be removing for the foreseeable future (until the wife upgrades to an EV). So i'm thinking of just having the electrician re-use that breaker for the new outdoor wiring, and size the wiring to support a matching 40A (32A continuous).

BTW: If anyone is interested in the Schneider 30A EVSE, give me a shout.

It's better practice to use a breaker that isn't much more than 120% of the rated draw - in this case, 20 amps. If you use a much larger breaker you increase the risk of a trip being delayed long enough for real damage to occur, possibly even a fire. We had a furnace blower actually burn up and fill the house with toxic smoke, because the person who installed the wiring did essentially what you propose: they installed or retained a 50 amp breaker for a 30 amp circuit. You can still use the larger wire, just keep the breaker near where it should be for the actual EVSE that's in place. That way the breaker will trip before the smallest wire in the unit can burn.

 

[jimmyz80]

Install a 30 amp breaker (more common and will still be safe) and upgrade it when you install a larger EVSE. The LCS-25 only draws 20 amps, so you don't want a breaker sized fully twice that.

The required breaker for the LCS-25 is 25A so double sizing everything would mean a 50A breaker. 40A would be the required breaker for a 30-32A EVSE, which is fairly standard and is why I was suggesting that size. My panel actually has a 40A breaker for the 30A EVSE in the garage that I'll likely be removing for the foreseeable future (until the wife upgrades to an EV). So i'm thinking of just having the electrician re-use that breaker for the new outdoor wiring, and size the wiring to support a matching 40A (32A continuous).

BTW: If anyone is interested in the Schneider 30A EVSE, give me a shout.

It's better practice to use a breaker that isn't much more than 120% of the rated draw - in this case, 20 amps. If you use a much larger breaker you increase the risk of a trip being delayed long enough for real damage to occur, possibly even a fire. We had a furnace blower actually burn up and fill the house with toxic smoke, because the person who installed the wiring did essentially what you propose: they installed or retained a 50 amp breaker for a 30 amp circuit. You can still use the larger wire, just keep the breaker near where it should be for the actual EVSE that's in place. That way the breaker will trip before the smallest wire in the unit can burn.

This makes a lot of sense now that you've spelled it out. Is this not addressed in the NEC anywhere?

 

[MikeD]

jimmyz80: I think the manufacturer of a device such as an EVSE specifies the appropriate breaker for that device.

 

[TimLee]

...
This makes a lot of sense now that you've spelled it out. Is this not addressed in the NEC anywhere?

Not really to the best of my knowledge.

But the code does continue to improve slowly.
Part of why ARC detection breakers are now required in parts of the home such as bedrooms for new installation.

Frayed extension cords were shown to be source of fires.
The small current draw of shorting frayed cord would never trip standard breaker.

The ARC detection breaker spots the voltage current waveform that indicates an ARC.

 

[CharlesinGA]

Article 625 of the NEC is quite clear on this.

ARTICLE 625—ELECTRIC VEHICLE CHARGING SYSTEM

625.14 Rating. Electric vehicle supply equipment shall have sufficient rating to supply the load served. For the purposes of this article, electric vehicle charging loads shall be considered to be continuous loads.

Going back to definitions in the NEC we find.....

ARTICLE 100—DEFINITIONS

Continuous Load. A load where the maximum current is expected to continue for 3 hours or more.

Then in Article 210 we find..........

ARTICLE 210—BRANCH CIRCUITS

II. Branch-Circuit Ratings
210.19 Conductors — Minimum Ampacity and Size.
(A) Branch Circuits Not More Than 600 Volts.
(1) General. Branch-circuit conductors shall have an ampacity not less than the maximum load to be served. Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the minimum branch-circuit conductor size, before the application of any adjustment or correction factors, shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load.

You should follow the instructions provided with the EVSE, they are approved and part of the UL/ETL listing process.

Charles

 

[CharlesinGA]

It's better practice to use a breaker that isn't much more than 120% of the rated draw - in this case, 20 amps. If you use a much larger breaker you increase the risk of a trip being delayed long enough for real damage to occur, possibly even a fire. We had a furnace blower actually burn up and fill the house with toxic smoke, because the person who installed the wiring did essentially what you propose: they installed or retained a 50 amp breaker for a 30 amp circuit. You can still use the larger wire, just keep the breaker near where it should be for the actual EVSE that's in place. That way the breaker will trip before the smallest wire in the unit can burn.

[/quote][/quote]

Correct practice per the NEC would dictate that you size the breaker and wire at 125% of the EVSE load. Thus a 30 or 32 amp EVSE requires a circuit designed and rated at 40 amps.

Charles

 

[jimmyz80]

Correct practice per the NEC would dictate that you size the breaker and wire at 125% of the EVSE load. Thus a 30 or 32 amp EVSE requires a circuit designed and rated at 40 amps.

Charles

I've still not seen anyone post the NEC section that addresses this. Your post from just a few minutes ago seems to only outline the rules for the wiring and not for the breaker. It also only specifies minimums, with no text addressing any sort of maximum.

 

[CharlesinGA]

The NEC is not a document that you can go to and get an answer all in one place. It requires putting it all together, and I made assumptions I should not have, that is, that if you tell someone the circuit should be a certain size, then we are discussing the entire circuit, meaning breaker, wire, and receptacle.

Article 240 of the NEC discusses overcurrent protection. It basically says that you protect a wire based on the wire tables found in Article 310. 310 has text that discusses everything related to conductors, type of wire, insulation types, exceptions, prohibitions, ampacities adjustment for various situations, etc.

It all boils down to the fact that Article 625 says use a CIRCUIT that is rated at 125% of the EVSE output. Article 210 defines the requirements for continuous load conductors, and what I am quoting below says that we use the tables for conductor sizes and protect the conductors based on those tables, given all of the adjustments, correction factors, and everything else.

Elsewhere, and its too late tonite for me to be looking it up, the NEC will tell us what size receptacles are allowed on what size circuits. The International Residential Codes also tell use this, but in a slightly different way.

ARTICLE 240—OVERCURRENT PROTECTION

240.4 Protection of Conductors. Conductors, other than flexible cords, flexible cables, and fixture wires, shall be protected against overcurrent in accordance with their ampacities specified in 310.15, unless otherwise permitted or required in 240.4(A) through (G).

 

[LeftieBiker]

Since the figure commonly given for maximum continuous draw is 80% of the circuit's rated maximum, I assumed that 120% would be the correct figure. 125% adds an extra margin, but in that case shouldn't the maximum continuous load be 75% of the rated maximum...? Or am I getting tangled up in the arithmetic?

 

[wmcbrine]

Since the figure commonly given for maximum continuous draw is 80% of the circuit's rated maximum, I assumed that 120% would be the correct figure. 125% adds an extra margin, but in that case shouldn't the maximum continuous load be 75% of the rated maximum...? Or am I getting tangled up in the arithmetic?

You are indeed. 125% is the correct inverse of 80%. That is to say: If x is 125% of y, then y is 80% of x.

x = 1.25y
y = 0.8x

x = (5/4)y
y = (4/5)x

Concretely,

50A * 0.8 = 40A
40A * 1.25 = 50A

 

[LeftieBiker]

Then 125% it shall be!

 

[smkettner]

Install a 30 amp breaker (more common and will still be safe) and upgrade it when you install a larger EVSE. The LCS-25 only draws 20 amps, so you don't want a breaker sized fully twice that.

If you have a 30 amp circuit you may as well get a Clipper Creek HCS-30 that charges at 24 amp rating.