davewill
Active Member
The max allowed would be 40a, not 42a. I would be very surprised if you have any problems, assuming the install is done correctly. However it's not code compliant and would not pass inspection.
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Wire size for wall charger
- Thread starter bbwex
- Start date
Not sure why you are laughing at this @dbldwn02 . it is a code violation and when you go to sell your house, depending on how good the home inspector is you might get called on it and require a licensed electrician come take all those outlets back out. NEC406.12
Hi guys. I plan on running wiring myself from the breaker box (attached to outside of house) through metal 1'' conduit (which will attached to house) to garage. Total distance is about 25 feet from breaker to charger. I ordered 4 AWG THHN wire x3 (red, black, green). I realize the ground doesn't need to be 4 AWG. I will use a 60A breaker at the box. I'm in Arizona so temperatures can get high (for reference).
I live in a remote area so electricians are not likely to come. I do have experience running electrical, bending and running conduit. Just wanted to check in and see if my setup makes sense.
Thanks!
I live in a remote area so electricians are not likely to come. I do have experience running electrical, bending and running conduit. Just wanted to check in and see if my setup makes sense.
Thanks!
Have you done a load calculation taking into account the number of rooms, HVAC, water heater and other appliances?
ScoobyDoo82
Member
I’m an electrician, so I feel compelled to chime in. You should use #6 wire. #8 is ok for a 40 amp load, but being that the wall charger is considered a “continuous” load, it would be best to derate the wire. Also, keep in mind that the 40 amp breaker is not what necessarily determines the wire size needed. The load is what determines the wire size in your situation.
What size is the main disconnect breaker in your panel? In other words, what service does your house have.. 100A, 125A, 200A? If your panel/service can support it, I would recommend using the wall unit to its maximum as charging/cost would be more efficient.
I have not so thanks for the great suggestion. On a 200A service line, what maximum utilization (in kw) should I be looking for in order to determine if a 60A breaker (48A continuous draw) is within safety limits. Last I did this (a few years ago) I was seeing a max draw of about 15kw when high load items such as AC and hot water heater were running (and other house hold items which added up to about 350w).
The service panel should have been sized for 200A service initially or during any upgrade, i.e. a heavy up. Is there a sub panel or only the main service panel?
Calculating Electrical Load Capacity for a Home
Calculating Electrical Load Capacity for a Home
dbldwn02
Active Member
I'm a certified home inspector (no licensing in Colorado), so I'll say with assurance, home inspectors don't touch the NEC or NFPA. Not their job. It's their job to refer to a licensed electrician, which almost never happens unless it's a blatant violation. (which tamper outlets aren't) I know what I need to do to put my house back to "code compliance" if I ever sell.
All I'm saying is, some people are perfectly capable of running 8/3 romex from their main to power an EVSE. You're also legally allowed to do so, with proper permitting. Anyone who says otherwise is mis-informed or trying to protect their own pocket book.
Thanks for the link. The service panel is sized for 200A. There is just one sub panel for our spa but that's in front of the actual spa. The spa is on a 50A breaker in the main panel and in its subpanel.
davewill
Active Member
#8 romex and a 40a breaker are already derated for the allowed 32a charging rate. He might want the bigger wire for future proofing, but not for the reasons you gave.
dbldwn02
Active Member
I charge at 24a on a 30a circuit. (short run) It can charge the 75kwh battery from 0-100% in 14 hours which is more than I drive any day of the week. If panel size/load calculations fall short, just downsize your charging capability, if it suits your needs. $3-5k to upgrade a panel isn't worth it, IMO.
I noticed a lot of people jumped to a different scenario to try to justify for the oversized circuit. They said, "I plug [tiny thing] into the 15A outlets in my house."
That application of multi-outlet branch circuits is entirely different. They are intended to have many small things plugged into them that aren't going to be matched to the amp level of the circuit. That is different and irrelevant to a dedicated circuit to a hard-wired appliance, which is the EVSE case. In that case, it is supposed to match the circuit level that the appliance's installation instructions recommend.
That application of multi-outlet branch circuits is entirely different. They are intended to have many small things plugged into them that aren't going to be matched to the amp level of the circuit. That is different and irrelevant to a dedicated circuit to a hard-wired appliance, which is the EVSE case. In that case, it is supposed to match the circuit level that the appliance's installation instructions recommend.
Yes, they absolutely do touch NEC code, unless they are bad home inspectors. Electricians get called out to do work on failed home inspection on the basis that the work is not up yo NEC code. I agree it is unlikely you will have a home inspector mention tamper resistant outlets, but they might.
dbldwn02
Active Member
Getting a little off topic but I'll post this last thing...
"There are two large national organizations for home inspectors in the United States: The American Society of Home Inspectors (ASHI), and the International Association of Certified Home Inspectors (InterNACHI). Both of these organizations make it clear in their Standard of Practice that home inspectors are not required to report on code compliance. The ASHI Standard of Practice states that “Inspectors are NOT required to determine compliance of systems and components with past and present requirements and guidelines (codes, regulations, laws, ordinances, specifications, installation and maintenance instructions, use and care guides, etc.).” InterNACHI says “The inspector is not required to determine compliance with codes or regulations.” If you look up the standard of practice for any licensed state, you’ll surely find similar language."
ScoobyDoo82
Member
ScoobyDoo82
Member
What reasons are you referring to?
Technically #8 is good for 55A, but not under these conditions. Sure it’ll work, but it’s not the safest way to go, especially if it’s Romex. At this rate you might as well just not even install a Tesla wall unit.
It has nothing to do with future proofing buddy. It’s about safety.
I have #4 THHN going to my wall unit off a 60A breaker. I’m well aware of what you are trying to say.
I think you are not understanding the difference between a regular branch circuit and continuous branch circuit.
I install car chargers for my customers several times a week. Last month I installed 12. I’ve probably installed well over 200 Tesla wall units and even more 14-50’s than I can keep track of. Every job has gone smoothly and the only call backs I get are to install subsequent chargers etc.. haven’t burned anyone’s house down yet.
Are you a licensed electrician by any chance? Seems like you’ve been listening to the $15/hr Home Depot guy a little too much.
Technically #8 is good for 55A, but not under these conditions. Sure it’ll work, but it’s not the safest way to go, especially if it’s Romex. At this rate you might as well just not even install a Tesla wall unit.
It has nothing to do with future proofing buddy. It’s about safety.
I have #4 THHN going to my wall unit off a 60A breaker. I’m well aware of what you are trying to say.
I think you are not understanding the difference between a regular branch circuit and continuous branch circuit.
I install car chargers for my customers several times a week. Last month I installed 12. I’ve probably installed well over 200 Tesla wall units and even more 14-50’s than I can keep track of. Every job has gone smoothly and the only call backs I get are to install subsequent chargers etc.. haven’t burned anyone’s house down yet.
Are you a licensed electrician by any chance? Seems like you’ve been listening to the $15/hr Home Depot guy a little too much.
davewill
Active Member
Did you even read the thread? We're talking about a 40a circuit to a 14-50, with a mobile adapter plugged into it. Maximum 32a charging, which the 40a circuit with #8 Romex is entirely adequate for. I should know, I've had an EVSE plugged into such a circuit, installed according to the manufacturer's instructions, for 10 years.
I am aware they aren’t required to determine compliance with code. You are paying for an opinion by someone who may or may not know what they are doing. But every electrical violation you find has to deal with violations of NEC code. Removing tamper proof violations is a code violation that an inspector might hit you on. Your little quote is about limiting the liability of the inspectors. They don’t have to, but they may.
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Bad take. Nothing wrong with running a evse on a 40 amp circuit charging at 32 amps using 8 romex.
32x1.25 = 40
8awg Romex is rated for 40 amps @ 60c
No issues.
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