Can someone please give me a sanity check on my charger wires?

[IamGaryGnu]

Hi - my wall charger went in last night. my local electricians are good, but I'm concerned. when they quoted me back in June, I let them know I wanted 60 amps for the charger. the run was to be roughly 125 feet. i was told they'd use 4 gauge, i even thought there was talk of aught gauge. Yesterday, the workers installed 6 gauge on a 200 foot run, and 50 amps. i didn't quite flip out, but i'm hopping mad.
the company owner said when they come back out (they didn't install a load module for the generator) that they'd switch to 60 amps at the panel, that the wiring is fine). i do know they spliced or similar part way in the attic - so i think they went from 6 gauge individual wires to a triple 6 gauge wire that was spliced in a box in the attic. I know i'm not being clear - 3 individual conducts joining the combined 3 conductor (romex or whatever).
so, with a 200 foot run, will a 60 amp be safe?
thanks!!!!!

 

[Bull]

Personally I'd be furious if they did that. It sounds like that had extra material that they tried to used to avoid purchasing new. 6ga on a 200' run (and spliced!) is the wrong size for a 60a circuit. I would demand that they reinstall with continous 4ga wire.

 

[roblab]

You're paying them to do what you want, so they should follow your orders. They need to come back and run 4 gauge wire all the way. In my opinion, there's nothing wrong with a junction box in the attic, as there are lots of connections in attics if you consider lights, etc. 6 gauge is probably all right (it's what I've got in my garage run) but you asked for 4 gauge. Simply put, they did not do what they said they'd do, and I agree with Bull, it looks like they're just getting rid of bits and pieces of wire from other jobs.

Hope they don't gouge you for re-doing the job.

 

[Bull]

You asked for a 60a circuit. 200' requires 4ga wire for 60a and has approx 3% voltage drop which will be ok. 125' will work with 6ga but is borderline needing 4ga for 60a. @roblab is correct that they should be following your orders. He is also correct that junction boxes are common in attics but they are a potential trouble point (overheated connections, improper access, etc) and should not have been part of your job.

Was the job permitted and inspected? Was the electrician licensed? No judgement, I do a lot of my own work and it always passes because I stay away from borderline specs. If not it might give you a bit of leverage with the electrician to do it better though.

They should re-do the job at no charge to you IMHO.

 

[Ostrichsak]

I'll pretty much echo what has been said here already in terms of getting what you requested and I will add that being as this is a circuit dedicated to EV charging I don't believe it's allowed to be "spliced" for any other purposes by code.

 

[ucmndd]

I will add that being as this is a circuit dedicated to EV charging I don't believe it's allowed to be "spliced" for any other purposes by code.

It's not all that uncommon to use a junction box to switch from THHN in conduit in exposed areas to (cheaper and easier to work with) NM Romex in protected spaces like an attic. I haven't seen anything in the NEC related to EVSEs that would prohibit this.

I think it's "fine" as installed with a 50 amp breaker - 200 feet is right on the edge at somewhere between 3-5% voltage drop but should be acceptable and pass an inspection. However, given that's clearly not what OP asked for, I agree with all of the previous sentiment that they should get what they paid for and what was agreed.

 

[IamGaryGnu]

You asked for a 60a circuit. 200' requires 4ga wire for 60a and has approx 3% voltage drop which will be ok. 125' will work with 6ga but is borderline needing 4ga for 60a. @roblab is correct that they should be following your orders. He is also correct that junction boxes are common in attics but they are a potential trouble point (overheated connections, improper access, etc) and should not have been part of your job.

Was the job permitted and inspected? Was the electrician licensed? No judgement, I do a lot of my own work and it always passes because I stay away from borderline specs. If not it might give you a bit of leverage with the electrician to do it better though.

They should re-do the job at no charge to you IMHO.

many thanks to you and roblab for the replies.
this company has 35 trucks. i've paid them some $25k over the last 13 months, between my generator, pool install (the pool company used them, but i added additional things) and this project.
I called a buddy who has about 35 trucks as well - and he said 4 gauge would be better, but 6 gauge will be fine.
i was only charged $1,595 (saying only - ha, my butt hurts!) - and another $200 will come up for the load shed module for the generator - was supposed to be 125 feet or so, but guess they either took a longer way, or had issues, etc.
if it's only a 3% drop i guess i can live with it. i didn't want to be an annoying whiner (which i am) and the difference inc harging speed seemed to be kinda small, but at the same time, this wasn't a discounted favor - so i wanted what i wanted.
the contract said 50 amp, and i crossed out and wrote 60 and initialed. this was back in june. i also added the load module, $200 per the general manager, and initialed that.
so yesterday, when the guys installed, they had 50 on their sheet, and no load module.
around here, it seems office staff is impossible to get, so i don't blame the guys in the field - it's the back office.
they know i won't pay them until this is right. based on my buddy and their assurances the 6 gauge is okay, i'm inclined to let it go - but yeah, i'll point out to the inspector and frankly hope they fail.
i also THINK the charger should be smart enough to limit current if it senses heat - but i wonder if that would be at the circuit panel some 200 feet away, at the splice, or at the wall charger.
sigh.
thanks again guys!

 

[IamGaryGnu]

It's not all that uncommon to use a junction box to switch from THHN in conduit in exposed areas to (cheaper and easier to work with) NM Romex in protected spaces like an attic. I haven't seen anything in the NEC related to EVSEs that would prohibit this.

I think it's "fine" as installed with a 50 amp breaker - 200 feet is right on the edge at somewhere between 3-5% voltage drop but should be acceptable and pass an inspection. However, given that's clearly not what OP asked for, I agree with all of the previous sentiment that they should get what they paid for and what was agreed.

thank you - i think what you described is exactly what they did.
i would LOVE for this to fail inspection but i don't think my town really checks that carefully.
i wish there was a way for the charger to report voltage received and amps received - i imagine even a 50 amp breaker SHOULD allow me to specify 60 amps in the config, for a 48 amp push which should be skirting the tolerances, but i also admit i only play an electrician on tv; i'm fine wiring stuff, but get nervous near the panels so i won't go there.
if 50 amp is acceptable, and i'm trying to push 48, should i just be okay unless there's some sort of a surge or spike?
ps i have 2 whole house surge protectors - to protect against lightning, etc.
thanks again!

 

[ucmndd]

i wish there was a way for the charger to report voltage received and amps received

Your car will tell you this while it's charging. If you want to get an idea of the voltage drop under load, plug your car in and start charging - take a look at the voltage reading just as charging starts and then again once it reaches full power. You can see this either in the center screen of the car or the mobile app. That will give you an idea of how much you're stressing/heating the circuit.

- i imagine even a 50 amp breaker SHOULD allow me to specify 60 amps in the config, for a 48 amp push which should be skirting the tolerances, but i also admit i only play an electrician on tv; i'm fine wiring stuff, but get nervous near the panels so i won't go there.
if 50 amp is acceptable, and i'm trying to push 48, should i just be okay unless there's some sort of a surge or spike?
ps i have 2 whole house surge protectors - to protect against lightning, etc.
thanks again!

I'd not configure the wall connector for a 60 amp breaker if there's only a 50 installed, particularly on such a long run, but that's just me.

 

[DerbyDave]

Once you configure your wall connector to your WiFi, you can access its temperature (an example from my wall connector: "pcba_temp_c":21.4,"handle_temp_c":19.5,"mcu_temp_c":26.4), voltage, status, and power usage. This is particularly helpful to see if the temperature of the wall connector is getting too hot. Access this by entering the following in a browser on the same network, substitution your actual IP address for the wall connector on your network in place of "connector IP Address":
http://"connector IP Address"/api/1/vitals

Example Only: http://192.168.1.135/api/1/vitals- Do Not Use

Output looks like: {"contactor_closed":false,"vehicle_connected":false,"session_s":0,"grid_v":244.6,"grid_hz":59.991,"vehicle_current_a":0.0,"currentA_a":0.0,"currentB_a":0.0,"currentC_a":0.0,"currentN_a":0.0,"voltageA_v":2.1,"voltageB_v":2.1,"voltageC_v":2.1,"relay_coil_v":11.9,"pcba_temp_c":21.4,"handle_temp_c":19.5,"mcu_temp_c":26.4,"uptime_s":941226,"input_thermopile_uv":-150,"prox_v":0.0,"pilot_high_v":11.8,"pilot_low_v":11.8,"session_energy_wh":2262.000,"config_status":5,"evse_state":1,"current_alerts":[]}

 

[Dave EV]

thank you - i think what you described is exactly what they did.
i would LOVE for this to fail inspection but i don't think my town really checks that carefully.
i wish there was a way for the charger to report voltage received and amps received - i imagine even a 50 amp breaker SHOULD allow me to specify 60 amps in the config, for a 48 amp push which should be skirting the tolerances, but i also admit i only play an electrician on tv; i'm fine wiring stuff, but get nervous near the panels so i won't go there.
if 50 amp is acceptable, and i'm trying to push 48, should i just be okay unless there's some sort of a surge or spike?
ps i have 2 whole house surge protectors - to protect against lightning, etc.
thanks again!

This will not fail because of NEC - your local inspector may fail it for other local reasons, though. NEC appears to have recommendations for voltage drop (<5% voltage drop for feeder+branch and <3% voltage drop for branch circuit), but not requirements. The car will handle the voltage drop just fine, but you will lose a bit more power to heat in the wires. There is no safety issue with 6 GA wire run and a 60A circuit assuming it's all THHN wire in conduit. Technically, the wire is rated up to 65A circuits.

40A on a 50A breaker - no worries. If you want to be able to charge at 48A on a 60A breaker - also no worries. Voltage drop will be about 8V / 3.3% at 40A and 9.5V / 4% at 48A. 4 GA wire would reduce the voltage drop to 5V / 2.1% and 6V / 2.5% at 40/48A respectively.

Ultimately - yeah, 4 GA would be preferred for this run, but 6 GA is "fine" - so it ultimately goes back to getting what you asked for in the first place.

Either way you go - I'd recommend not charging at the max rate unless you need to. It does push the equipment to the max so is more likely to cause overheating if there are any issues. If you stick with the 6 GA wire, maybe limit current to 36A most of the time (7V/3% drop) but don't worry about bumping it up should you need to charge in a hurry.

 

[Rocky_H]

i imagine even a 50 amp breaker SHOULD allow me to specify 60 amps in the config, for a 48 amp push which should be skirting the tolerances, but i also admit i only play an electrician on tv; i'm fine wiring stuff, but get nervous near the panels so i won't go there.

Yeah, don't do that stuff.

I don't see it very specifically addressed, so I will bring this part up. People keep talking about only the number of the wire gauge, but the type of wire make a really important difference in how many amps it is rated (allowed) to use. For the number 6 gauge, if that is individual wires in conduit, then yes, that is rated to 65A, and it would be acceptable for a 60A circuit. But if they did switch to Romex cable in the attic and were still using 6 gauge, then that is only rated to 55A and would NOT be allowed for a 60A rated circuit. If they used any 6 gauge Romex anywhere in this, but still used a 60A breaker, it's a code violation. Period.

And yeah, the car mostly won't care if the voltage is low, so 4-6% drop would still be OK. The car does have a little check on that for safety, where it looks at the unloaded voltage and then compares to the voltage when it has ramped up the current for charging, and if that does cause a large difference (don't know exactly how much), then it thinks that is a sign of a dangerous loose connection somewhere, and it will reduce the charging current to 3/4 of what it was to try to prevent creating a hot spot that could lead to a fire.

 

[DerbyDave]

Rocky_H, I still disagree with this. The Amperage is the maximum load on the circuit, not the breaker size. Since there is no 55A breaker (max amps allowed on #6 Romex), you are allowed by code to go to the next size breaker. 48A max load with this equipment on a 60A breaker can use #6 Romex. My electrician, his electrician and many other say it is OK. Would #4 be better? Sure. #6 is adequate for the installation and equipment. The long 200 foot run and the splice box would work much better with #4. Why do so many electricians on the web also say #6 is OK. Some say it isn't. Who knows!

In this calculator from Paige Wire: http://www.paigewire.com/pumpWireCalc.aspx, Amperes you are supposed to input is defined as:

"Amperes

– The number of amperes drawn by the load is to be obtained from the manufacturer of the equipment. For motors, the current must be obtained from tables 430-148 (single-phase) and 430-150 (3-phase) of the NEC. Care must be taken to follow the guidelines of the NEC with regard to the number plugged into the calculator."

Note that it is not the Amperes of the circuit breaker.

 

[ucmndd]

Rocky_H, I still disagree with this. The Amperage is the maximum load on the circuit, not the breaker size. Since there is no 55A breaker (max amps allowed on #6 Romex), you are allowed by code to go to the next size breaker. 48A max load with this equipment on a 60A breaker can use #6 Romex. My electrician, his electrician and many other say it is OK. Would #4 be better? Sure. #6 is adequate for the installation and equipment. The long 200 foot run and the splice box would work much better with #4. Why do so many electricians on the web also say #6 is OK. Some say it isn't. Who knows!

In this calculator from Paige Wire: http://www.paigewire.com/pumpWireCalc.aspx, Amperes you are supposed to input is defined as:

"Amperes

– The number of amperes drawn by the load is to be obtained from the manufacturer of the equipment. For motors, the current must be obtained from tables 430-148 (single-phase) and 430-150 (3-phase) of the NEC. Care must be taken to follow the guidelines of the NEC with regard to the number plugged into the calculator."

Note that it is not the Amperes of the circuit breaker.

I still think this post on the Mike Holt forums, which I believe I referenced in a previous discussion on this topic with you, is the most succinct and accurate explanation (with code references) as to why it’s a problem.

#6 NM-B on 60 amp breaker for 48A EVSE

I have been asked to connect an EVSE to an existing piece of 6/2 NM-B (ROMEX) in a new home that was installed by the home builder. the EVSE has a draw of 48 amps, so the breaker needs to be 60 amp (48 x 1.25 = 60). My understanding is that a continues load (the charger will be drawing maximum...

forums.mikeholt.com

In short, you could use the next size up breaker rule IF your calculated load doesn’t exceed the ampacity rating of the conductor. In the case of a continuous load on #6 romex, that maximum allowable amperage is (55 amps x 0.8) = 44 amps.

So if you could set the wall connector to draw 44 amps, this would be allowable and the correct solution would be to use the round up rule for a 60 amp breaker as you suggest. At 48 amps, you’ve exceeded the rating of the conductors and it’s a no-go.

As for “my electrician says”… I mean, there is a lot of layer and nuance to this topic and I’m not at all surprised that you’d maybe get 3 different answers from 3 different tradesmen. But if I’m gonna believe anyone on the internet, a 3-way consensus on the Mike Holt forums is about as good as it gets when it comes to matters of the NEC.

As I’ve also said in previous discussion - is this gonna burn the house down? Nah, probably not. Although if it were gonna, a 200 foot run with a splice or two would certainly be up there in the rankings as a candidate for something to go wrong. But again - “won’t burn your house down” =\= “code complaint”.

 

[Rocky_H]

The Amperage is the maximum load on the circuit, not the breaker size.

Sure, but EVERY piece of the circuit has to meet the appropriate level of that load.

Since there is no 55A breaker (max amps allowed on #6 Romex), you are allowed by code to go to the next size breaker.

We'll leave that there for now, but what, exactly, would you do with it?

48A max load with this equipment on a 60A breaker can use #6 Romex.

No, no, NO! False!
This is where you make the mistake and get it wrong!

I think I see where you're messing this up. You keep saying it has to go by the load, not the circuit breaker. So you keep saying 48A is the load, and 55A rating of the cable is larger, so it's fine. But the part you seem to be missing is that it's not just 48A; it's 48A CONTINUOUS. That means that the circuit rating can't just meet the 48A level. It has to meet 125% of 48A, which is 60A.

This goes back to the line I mentioned earlier, where EVERY piece of equipment in the chain must meet the requirement, and it doesn't. The wire is still insufficient. You did the "round up" rule on the breaker, which is fine, but then you made the false assumption that doing that meant the entire circuit had magically become rated as a full 60A circuit and could support 48A continuous operation with the 125% over allowance. IT HASN'T. The cable is still rated for 55A maximum. That can only allow 44A continuous load, and you're trying to run 48A That is wrong.

My electrician, his electrician and many other say it is OK.

Then I would never hire them.

Would #4 be better? Sure.

The word is "code compliant", not "better".

#6 is adequate for the installation and equipment.

No it isn't.

Why do so many electricians on the web also say #6 is OK. Some say it isn't.

Why do various people make mistakes in their jobs? That isn't something I can answer--it just happens.

Who knows!

NEC does.

In this calculator from Paige Wire: http://www.paigewire.com/pumpWireCalc.aspx, Amperes you are supposed to input is defined as:

"Amperes

– The number of amperes drawn by the load is to be obtained from the manufacturer of the equipment. For motors, the current must be obtained from tables 430-148 (single-phase) and 430-150 (3-phase) of the NEC. Care must be taken to follow the guidelines of the NEC with regard to the number plugged into the calculator."

Note that it is not the Amperes of the circuit breaker.

Yes. So apply that. If you pick that setting for the wall connector, the load is 48A. And NEC says that all EVSEs for charging electric cars must be defined as constant loads. So it is a 48A constant load. NEC says if you have a constant load, then you must use a circuit that is rated for 125% of that constant load. That would be 60A. So then you need to pick fixtures and wire and breaker that meet a 60A rating to build the circuit. 6 gauge Romex does not meet that rating. End of.

 

[DerbyDave]

Sure, but EVERY piece of the circuit has to meet the appropriate level.

We'll leave that there for now, but what, exactly, would you do with it?

No, no, NO! False!
This is where you make the mistake and get it wrong! This goes back to the line I mentioned earlier, where EVERY piece of equipment in the chain must meet the requirement, and it doesn't. The wire is still insufficient. You did the "round up" rule on the breaker, which is fine, but then you made the giant false assumption that doing that meant the entire circuit had magically become rated as a full 60A circuit and could support 48A continuous operation with the 125% over allowance. IT HASN'T. The cable is still rated for 55A maximum. That can only allow 44A continuous load, and you're trying to run 48A That is wrong.

Then I would never hire them.

The word is "code compliant", not "better".

No it isn't.

Why do various people make mistakes in their jobs? That isn't something I can answer--it just happens.

NEC does.

Yes. So apply that. If you pick that setting for the wall connector, the load is 48A. And NEC says that all EVSEs for charging electric cars must be defined as constant loads. So it is a 48A constant load. NEC says if you have a constant load, then you must use a circuit that is rated for 125% of that constant load. That would be 60A. So then you need to pick fixtures and wire and breaker that meet a 60A rating to build the circuit. 6 gauge Romex does not meet that rating. End of.

We are going to continue to disagree with this point, as we did in a previous discussion. As I have previously said, I am not an electrician, but many electricians also disagree with you. I just can't figure out why there is so much disagreement on what you are saying and the facts you correctly lay out among electricians. I will leave the decision on what is allowed to an electrician in my area that I trust. I am just a consumer.

 

[Rocky_H]

As I have previously said, I am not an electrician, but many electricians also disagree with you.

I would love to see some of these and hear what their supposed reasoning is, because usually there is something they are forgetting or overlooking that explains why they are getting it wrong. The most frequent I have seen is that they are used to installing circuits for things like ovens and dryers, and they think it's just a 48A intermittent load, like those other appliances. With EVSEs being a little bit new, they may not be aware that it is defined as a continuous load, so the circuit has to be 125% oversized.

The electricians and code analysis sites I have seen who say it is not allowed can point to very specific code citations to explain why. The electricians I have seen who think it is OK seem to not have much explanation other than "It's fine"

 

[DerbyDave]

So far I have used mine for over a year at full load for up to 8 hours. I have both felt the wire in the middle of the cable run, the wall connector backplate, and checked the temperature values tracked on the Gen 3 Wall Connector itself. The temps never seems to get more than very minimally warm, and the temperature values are also excellent according to the Wall Connector readings (printed circuit board temperature, handle temperature, and mcu temperature). Is there some other outward indicator I could check that would indicate the circuit is experiencing an overload which should be corrected? By the way, I think the Wall Connector itself will greatly assist in stopping problems with undersized circuits, and poor installations -- but this should be a last resort.

 

[MN-MS100D]

Ah, and there it is: "My installation is working just fine, so it will be ok" response. You are probably right. It will work fine. Just don't argue that it is coed compliant (especially with the Rock!)

 

[DerbyDave]

Ah, and there it is: "My installation is working just fine, so it will be ok" response. You are probably right. It will work fine. Just don't argue that it is coed compliant (especially with the Rock!)

I've had two electricians propose my installation in the identical manner, and I chose one. I only assume my electricians are providing me code compliant proposals, and that my installation will be safe and not endanger my home. I am not the professional, and the codes with my knowledge of the subject are difficult to understand. What I do find difficult to understand is that there is so much disagreement with electricians on the subject. The only result to me of all of this confusion is it seems a field in need of professional reform, or code reform -- or both.