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Wiring for Level 2 Charger
- Thread starter Joey D
- Start date
Believe it or not...I'm installing a ChargePoint Home Flex charger. My utility will reimburse up to $1500 for installation (and give a discount for off-peak charger use) but only for installation of specific units. Tesla's charger (which I would of course prefer) is not on the list. So I'll be using an adapter, but couldn't pass up the savings.
Just wanted to thank you and others for the installation advice. Electrician is here now doing the install with 6/2 MC.
Related...talking with the electrician this morning (who was going to initially use 6/2 Romex, and used 6/2 Romex on all prior installations), he said he brought up the issue at a code meeting just last night because of what I relayed to him. Said that locally inspectors would pass 6/2 Romex, but there are "seemingly conflicting code) to make it a bit of a grey area. Again...the "step up from a non existent 55 Amp breaker to 60" vs. use conductor rated for 60 Amps so-called debate which I agree is not really debatable. (Use conductor rated for the same amperage as the breaker.)
Anyway, he said he would likely be doing 6/2 MC from now on just to be on the safe side, and it can make installation easier for most applications since they don't need to deal with conduit.
I'll post a couple pics when done.
NewbyMaybe
Newby1Kenowby
Seems like it would cost a little more to have the best of both worlds. If an outlet was installed next to the charge point that would accommodate a Tesla mobile charger that would allow double the charge speed when necessary. A switch could prevent power to both at the same time?
Tesla mobile charger (plugged into a outlet) would not allow double charging speed....it would actually reduce it.
Don't want to mess with outlets for a couple reasons:
1) Max amperage for circuit with outlet is 40...hard wired circuit is 48.
2) Codes are such that a garage outlet would require a GFCI Breaker....these can actually interfere with internal GFCI protection built in to the charging unit and cause nuisance trips. CFGI breaker not needed for a hard wired unit.
3) seen too many instances (admittedly, anecdotal) of outlets failing...so prefer to avoid the possibility altogether.
Because my panel is not in the garage, they are also installing a switch for the circuit in the garage. This will make it easy to replace the charger if needed in the future. (Small conductor run from switch to the charger). If I ever wanted two chargers in my garage (don't think I would ever really need that), I could go with power sharing units that would limit total amperage on the circuit to 48 Amps.
NewbyMaybe
Newby1Kenowby
Hilarious that electricians at a code meeting have the same debates as us forum dwellers.
I agree with everyone on the 6/2 Romex issue. It isn’t code for a 60A breaker, but it’ll work nonetheless in most installs. IMHO, it gets dicey when routing it in a hot attic, through drilled joist holes, with other cable, under insulation. And that’s why code is conservative, so it can give you rules that will work for ALL normal installation practices.
I personally skip the whole issue and use 6/2 MC, which is more robust anyways and about the same cost as 6/2 Romex.
NewbyMaybe
Newby1Kenowby
The 2nd has a much better plug and the amperage is limited to eliminate the plug and outlet heat problems.
Wow, this is fascinating. There's no "seemingly conflicting code". It is just ignorance in not understanding and meeting ALL of the requirements of the "round up rule".
So let's say you put 55A 6 gauge Romex cable in. And you then "round up" to the 60A breaker. That's not a code violation...yet. It depends on what appliance load you are going to put on it. As it sits right there, it is technically a 55A rated circuit and hasn't violated anything with just open wires with nothing attached.
1. Put a wall connector on it configured to supply 40A continuous? X 125% means it needs at least a 50A rated circuit. Code passes.
2. Put a wall connector on it configured to supply 44A continuous? X 125% means it needs at least a 55A rated circuit. Code passes.
3. Put a wall connector on it configured to supply 48A continuous? X 125% means it needs at least a 60A rated circuit. Code fails.
Everyone knows condition #1, but you wouldn't bother with the round up rule there. Condition #2 would be fully acceptable and code compliant also, and is the narrow case where the round up rule would have any use. It's just very few EVSE products on the market that have a setting for 44A.
It's this weird thing where people round up the breaker, but then their brains shut off, and they think that applied the 60A rating to all of the wire in the circuit too, when it actually didn't. Nothing allows rounding up the rating of wire.
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Yup, I completely get it.
In any case, I wonder if the "brain shut off" is related to other "guidelines" (assumed equally as bad) that are done for other cases. For example, using a oversized breaker on a dedicated HVAC or AC line to prevent tripping on motor start-up. (Without ensuring conductors match the breaker rating.)
Bottom line: conductors should always be rated to handle the load at least as large as the breaker size.
Eric33432
Member
For anyone who comes along and reads this in the future, here are a few comments:
A very typical use case for 6/2 NM cable is an air handler with a 9600 watt heat strip and a ~3 amp fan motor, which draws 42 amps. Electricians do this all the time and it is perfectly safe. Since they do it all the time, they don't think sometimes and use it for EVSE on 60 amp breakers.
Also it is fine to use #12 NM wire or even #14 THHN wire in conduit with a 30 amp breaker for a condensing unit if the condensing unit draws, say 20 amps. Code allows this.
This guy, who is an excellent teacher, explains the round up rule in great detail:
A very typical use case for 6/2 NM cable is an air handler with a 9600 watt heat strip and a ~3 amp fan motor, which draws 42 amps. Electricians do this all the time and it is perfectly safe. Since they do it all the time, they don't think sometimes and use it for EVSE on 60 amp breakers.
Also it is fine to use #12 NM wire or even #14 THHN wire in conduit with a 30 amp breaker for a condensing unit if the condensing unit draws, say 20 amps. Code allows this.
This guy, who is an excellent teacher, explains the round up rule in great detail:
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Well, I thought I'd post a warning to others.
This morning I woke up to a car that had not charged to the set limit. Long story short, the Disconnect (safety switch) in the circuit failed.:
I spoke with my electrician...and he spoke with a state code official that he knows. This was the response:
This is pretty darn scary if you ask me. Most of us are aware of the challenges with receptacles (frequent mechanical plugging in and unplugging, along with frequently improper installation). Most of us understand why these circuits must be rated 20% higher than the continuous load, but apparently even more special consideration is needed to address the continuous "multi-hour" loads that EVs are pulling. For now, I am going to upgrade the switch to a "heavy duty" variant, and I am also going to de-rate my charging draw from 48 Amps to probably 40 Amps.
I don't know if my chargepoint EVSE was damaged...I find out tomorrow once the switch is replaced and power is back up.
What was extra worrying to me was that the circuit breaker did not trip.
This morning I woke up to a car that had not charged to the set limit. Long story short, the Disconnect (safety switch) in the circuit failed.:
I spoke with my electrician...and he spoke with a state code official that he knows. This was the response:
This is pretty darn scary if you ask me. Most of us are aware of the challenges with receptacles (frequent mechanical plugging in and unplugging, along with frequently improper installation). Most of us understand why these circuits must be rated 20% higher than the continuous load, but apparently even more special consideration is needed to address the continuous "multi-hour" loads that EVs are pulling. For now, I am going to upgrade the switch to a "heavy duty" variant, and I am also going to de-rate my charging draw from 48 Amps to probably 40 Amps.
I don't know if my chargepoint EVSE was damaged...I find out tomorrow once the switch is replaced and power is back up.
What was extra worrying to me was that the circuit breaker did not trip.
Why have the disconnect switch at all? I’m under the impression that’s only needed for something *over* 60A
Also I’m not sure if you’re aware, but ChargePoint now sells a native NACS connector which can be retrofitted - NACS Cable Kit | ChargePoint
Also I’m not sure if you’re aware, but ChargePoint now sells a native NACS connector which can be retrofitted - NACS Cable Kit | ChargePoint
I believe the disconnect is required for over 60 amps OR over 150 Volts. (This is 240 Volts of course). My breaker panel is not in the garage.
Thanks for the ChargePoint tip....I was actually one of the first to purchase the replacement NACS cable.
. (The images from this thread are from the initial installation, at which time there was no NACS cable available or even announced.)
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I believe the disconnect is required for over 60 OR over 150 Volts. (This is 240 Volts of course). My breaker panel is not in the garage.
Thanks for the ChargePoint tip....I was actually one of the first to purchase the replacement NACS cable.
Everywhere I’ve read says no disconnect needed for a 60A breaker and yes I’m confused by the wording in the NEC “For equipment rated more than 60 amperes or more than 150 volts to ground“. Maybe an electrician can chime in here.
EDIT: Our split phase residential system only provides 120V to ground. Each hot is 120V to ground, and only 240V relative to each other. So the NEC here is saying you DO NOT need a disconnect for EVSEs connected to 60A breakers or less, assuming non-commercial 3 phase power.
Personally, I would just can the disconnect and use Polaris connectors to connect the wires together.
And yes, run of the mill disconnects, which are meant for pool/spa breaker boxes or ACs, just aren’t built for EV charging.
Breaker didn’t trip because it didn’t exceed 60A draw for a long period of time. It is also possible that the car reduced charge current when it detected wonky electrical draws.
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It does seem odd that "requiring" a disconnect just seemingly introduces another failure point. I'll take your word for it on the need for a disconnect...but I will say every 240 V line on a 60 amp circuit in my house (spa, steam shower) has a local disconnect of some type.
EDIT:
The reason for it is servicing. AC units and pool equipment need frequent enough servicing so not having to tromp through the house to flip a breaker and flip the wrong one, is useful to have a local disconnect.
Personally I think this is a stretch for a requirement for EVSEs that will last 10+ years.
Anyways if you do use a disconnect make sure it is a heavy duty type. Again personally I’d just use Polaris connectors and call it a day.
The NEC gives EVSEs a pass if they use a 60A breaker or less. NO disconnect is needed. I assume this is because EVSEs don't need servicing as often as AC or pool/spas.
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